Risk Assessment of Heavy Metals in Groundwater for a Managed Aquifer Recharge Project

Abstract

Managed aquifer recharge (MAR) can address challenges pertaining to water quality and security, land subsidence, and aquifer degradation. This study has been conducted in the irrigated plains of Indus River Basin (IRB) of Pakistan, where groundwater is being used for drinking, agriculture, industries, and other commercial purposes and where the Punjab Government is implementing the MAR project. The study aims to assess the existing level of heavy metals and trace elements contamination in the groundwater and to set baseline data for the suitability of the site for the MAR project. Groundwater samples from 20 tubewells were collected from an area of 1522 km² to investigate the level of heavy metals concentration in groundwater and to assess its suitability for irrigation and drinking. Samples were analyzed for Aluminum (Al), Arsenic (As), Barium (Ba), Cadmium (Cd), Cobalt (Co), Copper (Cu), Chromium (Cr), Lead (Pb), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Selenium (Se), Strontium (Sr), and Zinc (Zn). To elucidate the contamination trend of these metals, the Heavy Metal Pollution Index (HPI), Heavy Metal Index (HI), geostatistical description, Pearson correlation analysis, and geospatial mapping were employed. Results showed that groundwater in the study area is not suitable for drinking and may pose serious health risks. It should be, however, generally suitable for irrigation. This concludes that the site is suitable for the implementation of a MAR project where the intended use of groundwater is for irrigation. It has been recommended that the groundwater may not be used for direct human consumption in the study area. It has been recommended, too, that targeted monitoring of identified hotspots and assessment of soil and crop uptake are conducted so that industrial or wastewater discharge into irrigation supplies may be prevented and controlled. For policy decisions, distinguishing irrigation suitability from potable-water safety is essential.

1. Introduction

Water is an essential ingredient of life. Only 2.5% of the total 1.4 billion km³ of water available is fit for drinking, cropping, and other industrial/commercial uses [1]. Access to safe and clean drinking water is one of the basic human rights for a healthy life [2]. However, more than 8.44 × 10⁶ of people have no access to pure drinking water, and approximately 2.3 × 10⁹ of people on earth still lack access to developed hygienic facilities [3]. Groundwater is the second largest reservoir of global available water, which represents about 96% of the planet’s accessible unfrozen freshwater resource and is a significant component of the hydrological cycle [4,5]. Different pathogens and contaminants leach into groundwater through sediments and aquifer rocks which affect its quality [6,7,8]. Deterioration of groundwater quality can be due to anthropogenic and geogenic reasons [9]. Pollution of water due to heavy metals is a serious concern due to their toxic and accumulating effects and persistence [10]. The quality of groundwater is more important when compared with quantity, as it plays a vital role for the safety of human health and conservation of ecosystems [11]. Cleanliness of contaminated groundwater is economically not viable [12]. Heavy metal groundwater contamination can be due to various anthropogenic and natural activities [13,14]. Heavy metals have been reported to contaminate groundwater after their geogenic release in aquifers due to oxidation/reduction in heavy metal-bearing minerals [15]. Some studies have reported the possible mechanisms underlying the geogenic release of heavy metals in groundwater as well as their distribution [16,17,18]. Likewise, many water-based activities and the over-exploitation of water resources also cause the contamination of aquifers with heavy metals. It is also reported that many industrial activities where untreated chemicals or waste are directly released into water bodies, either intentionally or accidentally, can pollute the ground and surface waters [19,20]. Heavy metals are highly persistent and toxic environmental pollutants [21,22,23]. Consumption of heavy metal-contaminated water consequently results in increased morbidity and mortality rates worldwide. Drinking metal-contaminated water can cause chronic and sub-chronic effects, which may involve reduced immunity, oxidative stress, and gastrointestinal ulcers and may also cause cancer [24].

Heavy metals and some trace elements in irrigation water cause soil contamination and are significant for irrigation water quality because of properties like biodegradation and thermo-degradation resistance [25]. These elements are hazardous, because they may build up to excessively high toxic concentrations before causing harm to plants, humans, and animals. Arsenic levels in the soil may produce stem chlorosis and root development restriction [26].

Pakistan, the sixth most populated country of the world, is also facing serious water shortage and quality issues. Groundwater commonly used for drinking purposes by 70% of the population in Pakistan contains different kinds of organic and inorganic pollutants, especially heavy metals [11]. The groundwater budget for Pakistan is in the danger zone, which means the extraction of groundwater is more than it recharges. This threat leads to mixing of fresh and brackish groundwater [27]. Studies revealed that almost two-thirds of surface water and groundwater in Pakistan has been polluted by heavy metals [28]. The principal sources of drinking water in Pakistan are ground and surface waters, which are in direct contact with trace metals [29]. Therefore, Pakistan ranks at number 80 among 122 countries regarding drinking water quality [30]. In addition to drinking water, groundwater is being used for irrigated agriculture and plays a vital role in rural livelihood and contributes to food security [31]. According to the ref. [32], non-communicable diseases and cardiovascular diseases are on the rise in Pakistan, which could be related to the heavy metal poisoning of drinking water. Poor drinking water quality is responsible for around 50% of diseases and 40% of fatalities in Pakistan. Recently, ref. [33] estimated that the drinking water of more than 53 percent of Pakistan’s total area (with more than 74 million people) was in danger of pollution by As, Cr, Fe, Ni, and Pb, using spatially weighted regression. Under this situation, Pakistan is confronted with water security challenges [34]. Although metals such as Pb are indeed major public health threats, other contaminants, including microbial pathogens (E. coli, Coliform bacteria), nitrates, pesticide residues etc., contribute significantly to disease burden. However, these aspects were beyond the scope of this research.

There are also groundwater governance challenges in Pakistan [35] including over depletion, the deterioration of quality due to climatic changes, and a tremendously increasing population [36]. The Government of Punjab is executing a MAR project by diverting floodwater in to the bed of the abandoned Old Mailsi Canal (OMC) in the south region of the Punjab province of Pakistan [37]. The purpose of this research is to evaluathe current status of heavy metals in groundwater to set a baseline for the MAR project. There are several regions/districts in Pakistan for which the information on heavy metal levels in groundwater, commonly used for drinking, is not available. In the study area groundwater is being used for drinking, agriculture, livestock, aquaculture, and industrial and other commercial uses. However, a major chunk of groundwater is being consumed in the agriculture sector [36,37]. Groundwater quality is of paramount importance during any intervention for groundwater management like managed aquifer recharge (MAR) [38,39,40]. During MAR, water from an external source—flood/river water, rainwater, and wastewater [39,41]—is transferred to the aquifer (sink) through some managed technique. Soils and groundwater become contaminated by the use of wastewater for the irrigation of vegetables and other crops in peri-urban areas, which can be hazardous for the MAR schemes [42]. During this whole process of MAR, it is imperative that the quality of water from both the source and the sink must be suitable for the intended purpose of MAR [43,44,45]. More suspended solids in wastewater reduce the infiltration rates during MAR [39,40]. Heavy metals contamination is a vital source of groundwater contamination, and their evaluation is also warranted for the success of any MAR project [45,46,47,48,49].

This study was therefore intended to estimate the quality of groundwater with respect to heavy metal contents for the MAR project in the study area. Recharged groundwater is to be used for drinking and irrigation purposes. As groundwater water recharge technologies are promoted rapidly in Pakistan, it is important to assess the chemical contamination level of target aquifers and source water. This research plays a significant role in analyzing the effectiveness of the MAR project. Findings of the research are applicable to other MAR projects in similar regions. Groundwater quality has also been compared with surface water (river and canal). Following this, this research aims to establish a baseline for the MAR project in terms of heavy metal contents. Subjected to current study outcomes, the MAR project being implemented in the Indus River Basin (IRB) in Pakistan will set a precedent for various other recharge projects being implemented in Pakistan.

2. Materials and Methods

2.1. Description of Study Area

This research is conducted in Vehari district, Punjab province, Pakistan (latitude 29.9719° N, longitude 72.4258° E), with an area of 1522 km². Surface elevation is about 140 m above mean sea level, and the area includes both rural and urban patches with 83% rural population. The population of Vehari district is approximately 2.9 million, with a 2.23% annual growth rate, and the majority of people rely on agriculture including livestock and aquaculture for their livelihood [50,51]. Figure 1 shows a map of the study area with sampling locations and other significant features.

The Vehari district is in the irrigated agricultural region of the country with limited industrial development [52]. Fruit orchards, fodder, sugarcane, wheat, and cotton are the major crops. Most of the irrigation is groundwater dependent as canal water is not adequate [53,54]. To meet the crop’s needs, several farmers have installed their own tubewells, which are mostly being run on electricity being the deep turbine type, which are not easily operated by diesel engines [37]. According to different sources, the aquifers of Vehari and Punjab province are said to be made mainly of unconfined alluvial deposits. In this region, there is a sedimentary complex with a thickness of around 400 m [6,51]. It has been assessed and reported that there is adequate potential for the underground storage of flood water in the study area [55].

Gradual increase in number of tubewells installed by farmers in the study area has been observed, mainly due to increasing cropping intensities. The extent of heavy metals contamination in the groundwater at the project site is imperative to set a baseline data for future comparison to evaluate the impacts of the MAR project. In Pakistan, generally, the standards fixed by FAO and WHO are followed for assessing the groundwater quality for irrigation on the basis of heavy metals [56].

Because of the growth in agricultural operations in this area, crop water requirements grew, resulting in over pumping groundwater, which harmed groundwater quality and quantity. Groundwater levels have dropped to 15 to 25 m below the surface of the land [36,37,57]. Average annual rainfall in the study area is less than 200 mm

2.2. Water Sampling and Laboratory Analysis

During May–June 2021, a total of twenty-three water samples were collected from the study region, with twenty being from groundwater, one from canal water, one from river water, and one from drain water. Standard procedures and protocol for sampling have been adopted from [58] and are given in [56]. However, due prevailing COVID-19 pandemic the sampling could not be repeated to track the seasonal changes. These samples have been analyzed for heavy metals and trace elements including Arsenic (As), Barium (Ba), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Manganese (Mn), Molybdenum (Mo), Nickel (Ni), Lead (Pb), Selenium (Se), and Zinc (Zn) The average depth of groundwater samples was 96 m, with depths ranging from 70 to 140 m (m). Samples were taken from the field according to American Public Health Association standard protocols and methodologies and US-EPA [58,59,60]. Some parameters like temperature, bore depth, well locations (x and y- georeferencing coordinates), ground surface elevations, static water levels, and water sampling source (tube well, drain, canal, and river) were measured/noted on site in the field utilizing portable instruments. Samples were collected, sealed, placed in containers, and transferred to the lab with due care and safety. The samples were kept cool (4 °C) until they were transported to the lab. All samples were labeled as HM1 to HM20 for groundwater, HM21 for drain, HM22 for canal, and HM23 as river water sample. Most groundwater samples were obtained from tubewells or turbines. The coordinates (x, y) and other basic information about the collected samples are given in Table S1 (Supplementary Materials). It is crucial to sample properly, because the quality of any analysis is directly tied to how effectively the sample is collected, and it is the first step toward ensuring an accurate result. All the samples were taken with caution and according to protocol. Samples were preserved by adding 10% HNO₃ to lower the pH of water samples less than 2 before sealing and packing [58]. COVID-19 SOPs, which include masks, social distancing, sanitizer use, and personal protective equipment such as gloves, caps, and glasses, were ensured during sampling. Tubewells were run for 3–5 min before taking samples to avoid the effect of static water on the health of samples. While capping the bottles, they were filled completely with water, and any trapped air was removed. It was ensured that the lid was securely fastened to prevent the sample from leaking during transport. Samples were packed, labeled, and kept in a cold place/container before being transported to lab with due care and safety. Samples were analyzed in the laboratory of Pakistan Council of Research in Water Resources (PCRWR) at Islamabad, Pakistan, as per standards and accredited procedures. Physicochemical parameters of water including pH, EC, and TDS also play a very important role in water quality assessment. This has been described in detail in [56], and as such are not part of this article.

2.3. Methods for Interpretation

The different methods described below have been used to interpret the concentration of various heavy metals in groundwater and surface water samples. Overall methodology for this research is depicted in Figure 2.

2.3.1. Geostatistical Analysis

Statistical analysis was performed to obtain the general picture of heavy metals contamination in the water samples, which includes mean, standard error, median, mode, standard deviation, variance, kurtosis, skewness, range, minimum and maximum values, and other parameters using MS Excel software. These parameters can interpret the various trends and extents of heavy metal concentrations in groundwater samples [61,62,63].

2.3.2. Geospatial Analysis

ArcMap10.6 Software has been used to interpolate the heavy metal concentration using IDW technique [64]. Different calculated indices have been plotted to depict the spatial pattern of groundwater quality in the whole study area to determine its fitness for irrigation and drinking purposes on the spatial scale.

2.3.3. Pearson Correlation Coefficient (r)

Pearson’s correlation coefficient, when applied to a sample, is referred to as the sample correlation coefficient or the sample Pearson’s correlation coefficient. We can obtain a formula for r by substituting estimates of the covariances and variances based on a sample into the formula below [65]:

$$\mathrm{r}={\displaystyle \frac{\sum \left(\mathrm{X}-\overline{\mathrm{X}}\right)\left(\mathrm{Y}-\overline{\mathrm{Y}}\right)}{\sqrt{\sum {\left(\mathrm{X}-\overline{\mathrm{X}}\right)}^2}\times \sqrt{\sum {\left(\mathrm{Y}-\overline{\mathrm{Y}}\right)}^2}}}$$

(1)

where X and Y are the parameters for which correlation coefficient is to be computed; $\overline{\mathrm{X}}$ and $\overline{\mathrm{Y}}$ are the mean values of X and Y parameters. This coefficient describes the correlation between different elements. Concentrations of elements originating from the same or similar source show significant correlations and vice versa [47,66]. The Correlation Matrix is obtained using IBM SPSS Statistic 26 software to perform this p-value test at 0.01 and 0.05 significance levels.

2.3.4. Heavy Metal Pollution Index (HPI)

Heavy Metal Pollution Index was calculated using the following formula [67,68,69,70]:

$$\mathrm{H}\mathrm{P}\mathrm{I}={\displaystyle \frac{{\sum }_{\mathrm{i}=1}^{\mathrm{n}}{\mathrm{W}}_{\mathrm{i}}\times {\mathrm{Q}}_{\mathrm{i}}}{{\sum }_{\mathrm{i}=1}^{\mathrm{n}}{\mathrm{Q}}_{\mathrm{i}}}}$$

(2)

where n is the number of parameters, W_i = unit weight of i-th parameter, and Q_i is the sub-index, calculated as

$${\mathrm{W}}_{\mathrm{i}}={\displaystyle \frac{\mathrm{K}}{{\mathrm{S}}_{\mathrm{i}}}}$$

(3)

$$\mathrm{K}={\displaystyle \frac{1}{{\sum }_{\mathrm{i}=1}^{\mathrm{n}}\frac{1}{{\mathrm{S}}_{\mathrm{i}}}}}$$

(4)

$${\mathrm{Q}}_{\mathrm{i}}=\sum _{\mathrm{i}=1}^{\mathrm{n}}{\displaystyle \frac{\left|{\mathrm{M}}_{\mathrm{i}}-\left.{\mathrm{I}}_{\mathrm{i}}\right|\right.}{({\mathrm{S}}_{\mathrm{i}}-{\mathrm{I}}_{\mathrm{i}})}}$$

(5)

where K is proportionality constant; S_i is standard/maximum permissible limit (MPL) of water for the i-th parameter; I_i is ideal value of the i-th parameter; and M_i is the monitored value of the i-th parameter.

2.3.5. Heavy Metal Index (HI)

Heavy Metal Index (HI) was calculated using Equation (6) [71], where MAC is the maximum allowable (permissible) concentration of the metal and C_i is the metal concentration in the samples of the i-th parameter.

$$\mathrm{H}\mathrm{I}=\sum {\displaystyle \frac{{\mathrm{C}}_{\mathrm{i}}}{\mathrm{M}\mathrm{A}\mathrm{C}}}$$

(6)

3. Results

A review of existing maximum permissible limit (MPL) values for all metals for drinking and irrigation purposes has been conducted, as provided by [3,72,73,74,75] and presented in Supplementary Materials Table S2. Different standards have been used to evaluate the suitability of water for drinking and irrigation uses on the basis of different parameters.

3.1. General Descriptive Analysis

Different statistical parameters were calculated to describe the extent of heavy metal concentrations in groundwater samples (n = 20), which are tabulated in

Table 1. Descriptive geostatistical analysis of concentration (ppb) of heavy metals in groundwater samples.

Statistical Parameter	Al	As	Ba	Cd	Co	Cr	Cu	Mn	Mo	Ni	Pb	Se	Zn
No. of samples (n)	20	20	20	20	20	20	20	20	20	20	20	20	20
Min	5.76	14.62	33.79	0.03	0.39	0.70	0.05	15.10	1.92	0.58	0.25	0.10	0.03
Max	2463.75	166.84	202.69	0.03	1.77	6.17	25.88	261.68	26.92	7.61	5.36	11.81	205.50
Standard Error	150.26	9.71	10.14	0.00	0.08	0.31	1.41	14.84	1.29	0.41	0.38	0.87	14.38
Mean	334.83	55.84	84.60	0.03	0.91	2.07	3.74	94.16	6.80	2.04	1.55	1.68	45.30
Limits for drinking	200	50	1300	3	50	50	2000	50	10	70	10	10	20
Limits for irrigation	5000	100	-	10	50	100	200	200	10	200	65	20	2000

Note: Red background color= mean values of Al, As, Mn, and Zn are beyond permissible limits for drinking water.

. The mean abundant elemental concentration of the heavy metals is in the order of Al > Mn > Ba > As > Zn > Mo > Cu > Cr > Ni > Se > Pb > Co > Cd. This shows that the highest concentration is of Aluminum and lowest is of Cadmium in the groundwater samples. However, this abundance sequence does not reflect the toxicological extents of the heavy metals. Some metals, even in small concentrations, can be fatal and more toxic since each metal has distinct geochemical behavior, natural background levels, and toxicological significance.

Heavy metal concentrations are an indicator of harmful effects on plant growth when such water is used for irrigation [76]. Concentrations of different heavy metals are shown in Figure 3.

3.1.1. Geostatistical Analysis

It has been found that the concentration of Aluminum (Al) in the samples ranges between 5.76 and 2463.75 ppb, with an average of 334.83 ppb. The average concentration of Al is more than the drinking water limit of 200 ppb but is below the MPL of 5000 ppb for irrigation use. The maximum concentration of Arsenic (As) is up to 166.84 ppb, with an average of about 55.84 ppb, which is beyond permissible limits for drinking purposes; however, it is suitable for irrigation. Barium was found up to 202.69 ppb, with an average of 84.60 ppb. The Cobalt measured from 0.39 to 1.77 ppb, with an average of about 0.91 ppb. The concentration of Chromium in the samples varied from 0.70 (ppb) to 6.17 (ppb), with an average of 2.07 (ppb). Copper was found up to 25.88 (ppb), with an average of 3.74 (ppb). The maximum concentration of Manganese is up to 261.68 (ppb), with an average of about 94.16 (ppb). The minimum and maximum concentration of Molybdenum was found to be 1.92–26.92 ppb and with an average of 6.80. The concentration of Nickel ranged from a minimum of 0.58 ppb to a maximum of 7.61 ppb, with an average value of 2.04 (ppb). In the present study, the concentration of Lead varied from 0.25 to 5.36 (ppb), with an average of 1.55 (ppb). The concentration of Selenium and Zinc varied from 0.10 to 11.81 (ppb) and 0.03 to 205.48 (ppb), respectively.

The concentrations of heavy metals are higher at location 8 and 11 in the study area, which indicates some local source of underground contamination, possibly from the Sukh Beas Drain (SBD), as both locations are in the vicinity of the SBD. Precipitation, irrigated fields, canals, and rivers are the major sources of aquifer recharge in the study area [37,77]. Chemical, anthropogenic, geogenic, and atmospheric pollutants carried out by these waters trickle into the groundwater [78] and cause local contamination of the groundwater. Over pumping is another reason for dropping the freshwater levels, which also results in the contamination of groundwater due to the intermixing of fresh and brackish water pockets [37,79].

3.1.2. Pearson’s Correlation Analysis

Correlation coefficients are calculated to indicate how each parameter connects with the others. Pearson’s correlation factor is a measurement that describes the strength of two variables. The correlation coefficient is a measure for determining how closely two variables are linearly connected and affect the value of each other. Its value is always between −1 and +1. A correlation coefficient is a statistical measure of how much one variable’s value affects the value of another. A positive correlation is a relationship in which the values of two variables rise or fall in lockstep. Negative values indicate poor or no correlation between the parameters [47,61,80]. A value of zero indicates no correlation at all [48,81]. When a parameter is compared to itself, it has a value of 1, indicating perfect correlation. Values of r > 0.7 indicate that the parameters are strongly correlated, whereas values of r between 0.5 and 0.7 indicate that the parameters are moderately linked [65,82]. Positive correlation values indicate that the parameters have a common origin, whereas negative correlation values indicate that the parameters have different ones [82]. Pearson’s correlation coefficient was applied with the understanding that there is small variability in the values of different parameters. However, it is acknowledged that Spearman’s rank correlation can provide better insights for the variable not exhibiting normality.

The Correlation Matrix is a tabular representation, as shown in

Table 2. Correlation matrix of heavy metals in water.

	Al	As	Ba	Cd	Co	Cr	Cu	Mn	Mo	Ni	Pb	Se	Zn
Al	1
As	−0.28	1
Ba	0.695 **	−0.15	1
Cd	b	b	b	b
Co	−0.09	−0.474 *	−0.07	b	1
Cr	0.977 **	−0.29	0.662 **	b	−0.12	1
Cu	0.26	−0.24	0.28	b	−0.15	0.28	1
Mn	0.35	0.12	0.33	b	−0.470 *	0.31	0.27	1
Mo	−0.31	−0.14	−0.39	b	0.16	−0.31	−0.28	−0.34	1
Ni	0.975 **	−0.28	0.657 **	b	−0.08	0.968 **	0.30	0.35	−0.42	1
Pb	0.635 **	−0.20	0.615 **	b	−0.12	0.611 **	0.17	0.16	−0.24	0.689 **	1
Se	−0.17	−0.07	0.06	b	−0.26	−0.20	0.43	0.40	−0.12	−0.19	−0.33	1
Zn	0.01	0.19	0.19	b	−0.11	−0.11	−0.19	0.17	−0.24	−0.03	0.20	0.25	1

Notes: ** Correlation is significant at the 0.01 level (2-tailed). * Correlation is significant at the 0.05 level (2-tailed). ^b. Cannot be computed because at least one of the variables is constant. Cadmium is Below Detectable Limit (BDL); it has 0.3 value in all the samples.

. It can be seen in Table 2 that Al has a significant correlation with Ba, Cr, Ni, and Pb; similarly, Ba has a significant correlation with Cr, Ni, and Pb; Cr has a significant correlation with Ni and Pb; and Ni has a significant correlation with Pb at the 0.01 level. At a significance level of 0.01, As, Co, Cu, Mn, Mo, Pb, Se, and Zn have no correlation with any other metal. At a significance level of 0.05, only As and Mn have a correlation with Co.

3.2. Water Quality for Irrigation

A major chunk of groundwater in the study area is consumed in the irrigation sector, and the main intended target of the MAR project is also to support the irrigators of the area. The findings of this research on the use of water for irrigation are described below.

3.2.1. Analytical Parameters

The concentrations of different metals in groundwater samples were compared with recommended maximum permissible limits (MPPLs) for irrigation use. A review of MPL at the global level is given in Supplementary Materials Table S2. A summary of the results of groundwater quality for irrigation use are tabulated in

Table 3. Suitability of groundwater for irrigation.

Name of Heavy Metal	Maximum Permissible Limits for Irrigation Water (ppb) [74]	Fit		Unfit
		No. of Samples	%	No. of Samples	%
Aluminum (Al)	5000	20	100%	-	-
Arsenic (As)	100	17	85%	3	15%
Cadmium (Cd)	10	20	100%	-	-
Cobalt (Co)	50	20	100%	-	-
Chromium (Cr)	100	20	100%	-	-
Copper (Cu)	200	20	100%	-	-
Manganese (Mn)	200	18	90%	2	10%
Molybdenum (Mo)	10	17	85%	3	15%
Nickel (Ni)	200	20	100%	-	-
Lead (Pb)	65	20	100%	-	-
Selenium (Se)	20	20	100%	-	-
Zinc (Zn)	2000	20	100%	-	-

Note: red color indicates which are not 100% fit.

, while detailed results for all samples are given in Supplementary Materials Table S3.

The results for groundwater analysis showed that Aluminum (Al), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), Selenium (Se) and Zinc (Zn) are within the permissible limits for irrigation. Arsenic (As) in three groundwater samples (HM4, HM7, and HM11), Molybdenum (Mo) in three samples (HM5, HM17, and HM19), and Manganese (Mn) in two groundwater samples (HM2 and HM9) were found beyond permissible limits for irrigation usage. However, overall, the average (twenty samples) concentration of these three metals is below the MPL for irrigation, which leads to the conclusion that, generally, groundwater can be used for irrigation. It has further been found that river and canal waters are fit for irrigation use, as all heavy metals have been detected below permissible limits.

3.2.2. Geospatial Analysis

Concentrations of all heavy metals in 20 groundwater samples have been plotted over the study area using Arc Map 10.6 software to depict the spatial distribution pattern of different metals in the study area for irrigation use, as shown in Figure 4.

It indicates that groundwater is mostly fit for irrigation, except very small patches of the study area are unfit due to excessive Arsenic (As), Molybdenum (Mo), and Manganese (Mn) concentrations. A small fraction of the study area contains groundwater unfit for irrigation with respect to As, Mn, and Mo, as per guideline values provided by [74].

3.3. Water Quality for Drinking

Groundwater is the major source of drinking water in the study region both in rural as well as urban areas. The water quality situation for drinking purposes is explained as follows.

3.3.1. Analytical and Geospatial Analysis

The results of the concentrations of heavy metals in all individual samples have been tabulated in

Table 4. Groundwater suitability for drinking purposes.

Heavy Metal	WHO Maximum Permissible Limits for Drinking Water (ppb)	Fit		Unfit
		No. of Samples	%	No. of Samples	%
Aluminum (Al)	200	14	70	6	30
Arsenic (As)	50	12	60	8	40
Barium (Ba)	1300	-	-	-	-
Cadmium (Cd)	3	20	100	-	-
Cobalt (Co)	50	20	100	-	-
Chromium (Cr)	50	20	100	-	-
Copper (Cu)	2000	20	100	-	-
Manganese (Mn)	50	6	30	14	70
Molybdenum (Mo)	10	17	85	3	15
Nickel (Ni)	70	20	100	-	-
Lead (Pb)	10	20	100	-	-
Selenium (Se)	10	18	90	2	10
Zinc (Zn)	20	12	60	8	40

, and geospatial plots of individual parameters, mapped using ArcMap10.6 are shown in Figure 5.

Results have revealed that Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Nickel (Ni), and Lead (Pb) were all found to be within permissible limits for drinking, but 70 percent with respect to Manganese (Mn); 40 percent with respect to Zinc (Zn) and Arsenic (As); 30 percent with respect to Aluminum (Al); 15 percent with respect to Molybdenum (Mo); and 10 percent with respect to Selenium (Se) groundwater samples are values unfit for drinking. This indicates that the overall quality of groundwater is not fit for human consumption, and continuous use of such water may cause adverse effects on human health. As such, groundwater cannot be recommended directly for drinking purposes. Concentrations of six metals (Al, As, Mn, Mo, Se, and Zn) out of a total thirteen are beyond permissible limits for drinking, as the quality of groundwater is very critical for human survival. Some of these heavy metals, especially As and Zn, are very dangerous pollutants for groundwater, which pose adverse impacts on human health if the water is used continuously by the community [81]. Ref. [83] analyzed 156 groundwater samples in the Vehari district and found that about 95% of samples were beyond permissible limits for drinking water. Ref. [6] analyzed 60 groundwater samples in the vicinity of the Sutlej River in Vehari and found that 50% of samples were beyond drinking water guidelines. Similar results were found by [52], who analyzed 129 groundwater samples for heavy metals and other parameters and found that groundwater is not suitable for drinking purposes in Vehari. As such, groundwater is not fit for drinking with respect to hazardous and poisonous metals and cannot be permitted for drinking water. In addition to individual metals, further investigation has been carried out by calculating two indices to describe the overall combined effect of all metals’ groundwater quality.

3.3.2. Heavy Metal Pollution Index (HPI)

HPI values for tubewells are calculated and grouped into five classes from low (<25) to high (>100) [67,68], as shown in

Table 5. Heavy Metal Pollution Index (HPI) of groundwater samples for drinking purposes.

(HPI) Range			Results
Class		Type of Water	No. of Sample	% Sample
1	<25	Excellent	1 (HM15)	5
2	26–50	Good	4	20
3	51–75	Poor	7	35
4	76–100	Very Poor	3 (HM5, HM6, HM19)	15
5	>100	Unsuitable	5	25

.

The HPI value in the study area ranged from 14.25 to 64.46, with an average of 26.43. The result of HPI for the groundwater samples indicated that only one sample (HM15) falls under the excellent class of HPI. Tubewell number 15 is an electric turbine (95 m deep) in Mouza Ghulam Qadir near the Sutlej River and PI Link canal, which are freshwater recharge sources for this area. Twenty percent of total samples fall under good class, 35% fall under poor class, 15% under very poor, and 25% fall under the unsuitable class. Three samples, 5, 6 and 19, fall under very poor class; out of these, HM5 is taken from Chak No. 85/WB, which is from an electric tubewell, sample no. 6 is taken from an electric turbine at an Agriculture Seed Farm in the Vehari city area, and sample no. 19 is from an electric turbine in Chak no. 45 3/EB. Both samples 5 and 6 fall in a suburb of the Vehari Urban Centre. HPI values above 100 have been considered a threat for the use of groundwater for drinking purposes. It is evident from this that only 25% of groundwater samples have been found suitable for drinking purposes, the rest of the samples, 75%, have been found unfit for drinking purposes.

3.3.3. Heavy Metal Index (HI)

Calculated values of the HI are presented in

Table 6. Heavy Metal Index results for groundwater samples.

Heavy Metal Index (HI)			Results
Class	Value	Classification	No of Samples	% Samples
1	<0.3	Very Pure	-
2	0.3–1.0	Pure	-
3	1.0–2.0	Slightly Affected	-
4	2.0–4.0	Moderately Affected	4	20
5	4.0–6.0	Strongly Affected	4	20
6	>6	Seriously Affected	12	60

.

And the comparison between HPI and HI is shown in

Table 7. HPI and HI of average groundwater, river, drain, and canal water for drinking use.

Sample No.	Type of Water	HPI		HI
		Value	Class	Value	Class
HM (Avg1–20)	Avg of 20 GW samples	82.226	Very Poor	10.434	Seriously Affected
HM21	Drain	75.504	Very Poor	6.018	Seriously Affected
HM22	Canal	67.777	Poor	8.423	Seriously Affected
HM23	River	70.694	Poor	6.283	Seriously Affected

. HI is used to classify the ground water for drinking purposes. According to this index, 20% of total samples falls under the moderately affected class of HI. And 20% of the total samples are strongly affected, while the rest of the total samples, 60%, are the seriously affected class of HI. The HP values above 6 have been considered a threat for the use of groundwater for drinking purposes.

3.4. Overall Groundwater Quality

Overall groundwater suitability for irrigation and drinking uses has been depicted in Figure 6.

From this descriptive analysis, it can be inferred that groundwater is mostly not suitable for drinking use but can generally be used for irrigation. Excessive concentrations of heavy metals in drinking water pose adverse effects on human health like kidney damage. Exposure to heavy metals adversely affects the general functions of the human body, even at low concentrations. Some metals are even nephrotoxic and can cause biochemical disorders. On the other hand, surface water (canal and river) is generally fit for drinking as well as for irrigation uses. Only one drain (Sukh Beas Drain) in the study area was sampled, and flow at the time of sampling (June 2020) was very low, and not many effluents were flowing in the drain. As such, drain water has not been found to be very contaminated.

Plants are poisoned by heavy metals via different ways: (i) Similarities with nutritional cations resulting in an absorption competition at the root surface; for example, As and Cd compete with P and Zn, respectively; (ii) heavy metals directly interact with functioning proteins and sulfhydryl groups (-SH), disrupting their structure and function, rendering them inactive; and (iii) essential cations are displaced from particular binding sites, causing macromolecules to collapse [56].

In this context, heavy metal exposure has been linked to a reduction in mitotic activity in a variety of plant species, resulting in reduced root development [83]. Heavy metals are more critical for human consumption and pose very toxic and poisonous impacts on human health [84]. This indicates that groundwater quality with respect to Al, As, Mn, and Se is not suitable for drinking. These are hazardous metals and will pose severe health concerns for the inhabitants of these locations. However, based on some individual elements, the groundwater seems to fit for drinking. Therefore, HPI was evaluated for assessment of the overall quality.

3.5. Suitability of Surface Water

The concentrations of different metals in groundwater samples were compared with the recommended MPL for irrigation and drinking uses.

For comparison, surface water samples were also analyzed and compared with the recommended MPL for irrigation by FAO. Three samples were collected from different water bodies like one sample from the Sukh Beas Drain, one from the Pakpatan-Islam Link Canal, and one from the River Sutlej. Results of the analysis indicated that these waters are suitable for irrigation uses, as per the WHO and FAO.

Groundwater samples were tested against the recommended MPL for drinking. Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Nickel (Ni), and Lead (Pb) were all found to be 100 percent within permissible limits. A total of 70 percent of groundwater samples are unfit with respect to Manganese (Mn), while 40 percent of groundwater samples are unfit for Zinc (Zn) and Arsenic (As), 30 percent of groundwater samples are unfit for Aluminum (Al), 15 percent samples are unfit for Molybdenum (Mo), and Selenium (Se) showed 10 percent unfit samples for the MPL for drinking. The results indicated that, as such, groundwater cannot be recommended directly for drinking purposes. Concentrations of six metals (Al, As, Mn, Mo, Se, and Zn) out of the total thirteen are beyond permissible limits for drinking, as the quality of groundwater is very critical for human survival. Some of these heavy metals, especially As and Zn, are very critical pollutants for groundwater, which pose impacts on human health if the water is used continuously by the community [81].

Continuous use of groundwater for drinking purposes may entail human health issues. Therefore, the use of groundwater is not recommended for direct human consumption. All the surface water samples were analyzed with recommended maximum permissible limits (MPL) for irrigation. The results showed that, in the drain sample, Selenium is beyond the MPL; in the canal sample, Manganese is more than the MP; and Aluminum, in the river sample, is more than the MPL.

Results have revealed that surface water is generally fit for irrigation use. All concentrations are within the permissible limits, except the Mn in canal water and Al in canal water.

The HPI and HI indexes were also used to classify the surface water for drinking purposes and compared with the average of the groundwater samples (n = 20). The result of the average of the groundwater samples and drain samples falls within the very poor class of HPI for drinking purposes, while the canal and river water samples fall within the poor class of HPI for drinking purposes. The samples were also classified according to the Heavy Metal Index (HI) for drinking purposes. According to the results of the HI, all the samples fall within the seriously affected class of water. Table 7 depicts the comparison between HI and HPI.

Based on the Heavy Metal Index and MPLs, this study concludes that the groundwater and surface water available in the Vehari district is unsafe for drinking and human consumption. Ref. [52] also found that the groundwater used for drinking in three tehsils of the Vehari district is not optimum or entirely fit for drinking based on numerous parameters, including Pb, Cd, Fe, cations ratios, alkalinity, and chloride concentrations. Compared to WHO-permitted limit values, the Pb, Cd, and Fe concentrations were 93 percent, 100%, and 68 percent higher, respectively. Cu, Mn, and Ni contents in certain water samples were also greater than the allowed limits. For the Vehari district [85], it was also found that the drinking water quality in high schools and higher secondary schools is inadequate. According to the WHO recommendations, drinking water in schools in Tehsil Mailsi, Burewala, and Vehari is unsafe for children due to increased levels of As. As concentrations of >10 g/L were found in 70% of drinking water samples from 164 schools.

Drinking contaminated water is among the major causes of mortality and many severe diseases in many developing countries like Pakistan [33]. Heavy metals are usually toxic at very low concentrations, while trace elements are not toxic at low concentrations. Some of the trace elements are micronutrients which we need in minute amounts for the growth and development of our body, being that they are dietary elements [86]. Smelting of non-ferrous metals, thermal power plants utilizing fossil fuels (coal), particle deposition, and minor sources such as arsenical insecticides and wood preservatives are all sources of Arsenic in polluted groundwater [10]. In humans, Arsenic can cause lung cancer, kidney cancer, bladder cancer, and skin cancer (hyperkeratosis and pigmentation), as well as multi-organ dysfunction, encephalopathy, bone marrow depression, and hepatomegaly [86]. The source of Zinc is irrigation with contaminated wastewater (industrial and sewage). It can cause respiratory problems and significantly decrease the erythrocyte superoxide dismutase concentration in adult females [48]. For comparison, surface water samples were also analyzed and compared with the recommended MPL for irrigation. Three samples were collected from different water bodies like one sample from the Sukh Beas Drain, one from the Pakpatan-Islam Link Canal, and one from the River Sutlej. The results indicated that all samples are fit for irrigation with respect to all heavy metals.

As shown in Table 4, groundwater cannot be recommended for drinking because it is unfit on the basis of different parameters.

Continuous use of groundwater for drinking purposes may entail human health issues. Therefore, the use of groundwater is not recommended for human consumption in the study area. All surface water samples were analyzed and compared with the recommended maximum permissible limits for irrigation. The results showed that, in the canal sample, Manganese is more than the MPL and Aluminum in the river sample is beyond the MPL. The results of these are shown in

Table 8. Suitability of surface water for drinking.

Heavy Metal	Maximum Permissible Limits for Drinking Water (ppb)	Canal		River
		Value (ppb)	Remarks	Value	Remarks
Al	200	22.03	Fit	213.57	Unfit
As	50	31.38	Fit	9.36	Fit
Ba	1300	71.05	Fit	52.57	-
Cd	3	0.03	Fit	0.03	Fit
Co	50	2.07	Fit	0.44	Fit
Cr	50	0.96	Fit	2.05	Fit
Cu	2000	1.09	Fit	3.13	Fit
Mn	50	138	unfit	16.83	Fit
Mo	10	2.33	Fit	2.87	Fit
Ni	70	2.31	Fit	2.08	Fit
Pb	10	0.25	Fit	0.25	Fit
Se	40	0.1	Fit	9.1	Fit
Zn	3000	0.03	Fit	9.49	Fit

.

The results shown in

Table 9. Heavy Metal Index (HI) results of groundwater samples.

Heavy Metal Index (HI)			Results
Class	Value	Remarks	No. of Samples	% of Samples
1	<0.3	Very Pure	-
2	0.3–1.0	Pure	-
3	1.0–2.0	Slightly Affected	-
4	2.0–4.0	Moderately Affected	4	20
5	4.0–6.0	Strongly Affected	4	20
6	>6	Seriously Affected	12	60

have revealed that surface water is generally fit for drinking use, except the level of Al in river water and Mn in canal water is beyond permissible limits.

From this descriptive analysis, it can be inferred that groundwater is mostly not suitable for drinking use but can be used for irrigation. Excessive concentrations of heavy metals in drinking water pose adverse effects on human health like kidney damage. Exposure to heavy metals adversely affects the general functions of the human body, even in low concentrations. Some metals are even nephrotoxic and can cause biochemical disorders. On the other hand, surface water (canal and river) is fit for drinking as well as for irrigation uses. Only one drain (Sukh Beas Drain) in the study area was sampled, and flow at the time of sampling (June 2020) was very low, and not many effluents were flowing in the drain. As such, drain water has not been found to be very contaminated. This indicates that groundwater quality with respect to Al, As, Mn, Se, and Zinc is not suitable for drinking. These are hazardous metals and will pose severe health concerns for the inhabitants of these locations.

3.5.1. Heavy Metal Pollution Index (HPI)

The HPI was calculated (Equation (2)) for each sample, and to obtain the spatial distribution across the study area, it was interpolated using ArcMap 10.6. The HPI value in the study area ranges from 14.25 to 64.46, with an average of about 26.43. HPI classification and results are shown in Table 5.

The HPI values was grouped into five classes from low (<25) to high (>100) [67,68]. The result showed that one sample (HM15−5% of the total samples) fell under the excellent class of HPI, which is taken from the electric turbine in Mouza Ghulam Qadir near the Sutlej River and PI Link canal, which are the recharge sources for this area. HPI for twenty percent of the total samples fall under good class and 35% fall under poor class. Three samples, 5, 6 and 19, fall under the very poor class, which is about 15% of the total samples, where sample no. HM5 is taken from Chak no. 85/WB, which is from the electric tubewell, sample No. 6 is taken from an electric turbine at an Agriculture Seed Farm in Vehari; and sample No. 19 is from an electric turbine in Chak no. 45 3/EB. Twenty-five percent of the total samples are unsuitable for drinking purposes, according to the HP Index. HPI values above 100 have been considered a threat to the use of groundwater for drinking purposes. It is evident from this that only 5% and 20% of groundwater samples have been found to be excellent or good for drinking purposes, and the rest of the samples, 75%, have been found unfit, poor, or very poor for drinking purposes. This concludes that groundwater is generally not fit for drinking purposes.

3.5.2. Heavy Metal Index (HI)

The HI for drinking uses was calculated by using Equation (6) and results with classification are given in Table 9. According to this index, 20% of total samples fall under the moderately affected class of HI for drinking water. Twenty percent of total samples are strongly affected, while the rest of the samples, 60%, are seriously affected. The HP values above 6 have been considered as a threat to the use of groundwater for drinking purposes, posing serious adverse impacts for inhabitants living in the area. This concludes that groundwater is not fit for drinking uses.

3.5.3. Surface Water Suitability and Comparison with Groundwater

The HPI and HI indexes were also used to classify the surface water for drinking purposes and compared with the average of the groundwater samples (n = 20). The results tabulated in

Table 10. Comparison of groundwater and surface water quality using HPI and HI.

Sample No.	Type of Water	HPI		HI
		Value	Class	Value	Class
HM (Avg; n = 20)	Avg GW	82.23	Very Poor	10.43	Seriously Affected
HM21	Drain	75.50	Very Poor	6.02	Seriously Affected
HM22	Canal	67.78	Poor	8.42	Seriously Affected
HM23	River	70.69	Poor	6.28	Seriously Affected

indicate that the average values of groundwater samples and drain water samples fall under the very poor class of HPI and seriously affected class of HI for drinking purposes, while canal and river water samples fall within the poor class of HPI for drinking purposes. According to the Heavy Metal Index (HI), for drinking purposes, all the samples fall within the seriously affected class of water. Canal and river water are also not suitable for direct human consumption as per the load of heavy metals in the water. The water is contaminated with heavy metals.

4. Risk Assessment and Discussions

Plants are poisoned by heavy metals in four different ways. (i) Similarities with nutritional cations, resulting in absorption competition at the root surface; for example, As and Cd compete with P and Zn, respectively. (ii) Heavy metals directly interact with functioning proteins and sulfhydryl groups (-SH), disrupting their structure and function, rendering them inactive. (iii) Essential cations are displaced from particular binding sites, causing macromolecules to collapse [87].

Plants growing in heavy metal-rich soils experience reduced growth and yield, suggesting that heavy metal toxicity is a factor in the stressed plants’ overall growth performance [88]. Cell division and elongation are both involved in root growth. In this context, heavy metal exposure has been linked to a reduction in mitotic activity in a variety of plant species, resulting in reduced root development [89].

Smelting of non-ferrous metals, thermal power plants utilizing fossil fuels (coal), particle deposition, and minor sources such as arsenical insecticides and wood preservatives are all sources of Arsenic in polluted groundwater [10]. In humans, Arsenic can cause lung cancer, kidney cancer, bladder cancer, and skin cancer (hyperkeratosis and pigmentation), as well as multi-organ dysfunction, encephalopathy, bone marrow depression, and hepatomegaly [86]. The source of Zinc is irrigation with contaminated wastewater (industrial and sewage). It can cause respiratory problems, significantly decreasing the erythrocyte superoxide dismutase concentration in adult females [48].

This study evaluated the heavy metal concentration in 20 groundwater samples to assess irrigation and drinking suitability and the potential health implications associated with the use of this water. The presence of Manganese in the earth’s crust causes high Manganese concentrations. Iron and Manganese-containing minerals can be dissolved and held in a solution by water percolating through soil and rock [90]. In our study, the concentrations of Manganese (Mn) ranged from 15.10 to 261.68 ppb (mean 94.16 ppb). Importantly, only a small fraction of samples exceeded the FAO/WHO guideline of 200 ppb for Mn. Thus, Mn risk exceedances were rare and were detected in isolated locations; the overall spatial pattern indicates that most groundwater is within acceptable limits for Mn with respect to irrigation.

It is also critical to distinguish between micronutrients and toxic heavy metals. Micronutrients such as Zn, Cu, and Mn are required for plant growth at low concentrations but may become phytotoxic if inputs are excessive or soils retain them over time. In contrast, Pb, Cd, and As are non-essential and toxic even at low concentrations because they can accumulate in edible plant parts and enter the food chain. Excessive Copper (Cu) can inhibit root growth and induce leaf chlorosis, and excessive Zn and As can inhibit the root growth and stem chlorosis [91].

As reported by [91], the presence of Al in acidic soils can reduce the productivity; further, Lead (Pb) and Cadmium (Cd) are typically limited because, when dissolved in water or soil, they can accumulate in the crop, posing a health risk to humans. As a result, the FAO has set restrictions on trace element concentrations in irrigation water. Some of the heavy metals and some trace elements in irrigation water cause soil contamination and are significant for irrigation water quality because of properties like biodegradation and thermo-degradation resistance [56] These elements are hazardous because they may build up to excessively high toxic concentrations before causing harm to plants, humans, and animals [56]. Heavy metals are usually toxic even extremely low concentrations, while trace elements are not toxic at low concentrations. Some of the trace elements are micronutrients, which we need in minute amounts for the growth and development of our body, being that they are dietary elements [86].

Mechanisms and sources of elevated Mn in groundwater is commonly linked to natural geologic sources and the reductive dissolution of Mn-bearing minerals during groundwater circulation [90]. Anthropogenic inputs (industrial effluents, agricultural return flows, and wastewater irrigation) may contribute to elevated Zn or Cu in isolated areas. The present dataset shows that micronutrient concentrations are generally within agronomic ranges for most sampling locations, whereas exceedances of toxic elements (if any) are explicitly reported against MPLs and summarized using the Heavy Metal Pollution Index (HPI) and Hazard Index (HI).

Heavy metals are more critical for human consumption and pose very toxic and poisonous impacts on human health [84]. Based on the Heavy Metal Index and MPLs, this study concludes that groundwater and surface water in the Vehari district are unsafe for drinking and human consumption. Contamination severity levels on the basis of HPI are in the order of groundwater > drain water > river water > canal water. Results have revealed that groundwater is more contaminated with heavy metals compared to surface water. It has been found that, on the basis of HPI, groundwater is 8, 18, and 14 percent more contaminated with heavy metals compared with drain, canal and river waters, respectively. Similarly, the results of HI have also revealed that groundwater is more contaminated compared to surface water. It has been found that groundwater is 42, 40, and 19 percent more contaminated on the basis of HI compared to drain, river, and canal water, respectively. Overall, groundwater is loaded with more heavy metals compared to surface water.

Neither groundwater nor surface water are generally suitable for human consumption. Ref. [52] also found that the groundwater used for drinking in three tehsils of the Vehari district is not optimum or entirely fit for drinking based on numerous parameters, including Pb, Cd, Fe, cations ratios, alkalinity, and chloride concentrations. Compared to WHO-permitted limits, it was found that Pb, Cd, and Fe concentrations were 93 percent, 100%, and 68 percent higher, respectively. Cu, Mn, and Ni contents in certain water samples were also greater than the allowed limits.

Comparison with previous studies like [52,92] reported poor drinking water quality in parts of the Vehari district (e.g., frequent exceedances of Pb, Cd, Fe, and As). Those studies were primarily drinking water focused and used different sampling networks and endpoints. Our irrigation-focused assessment should not be conflated directly with drinking water risk: although the presence of heavy metals in irrigation sources can eventually affect soil and crops [52] (and thus indirectly affect human exposure), the immediate public health implications differ. Where previous authors found high levels of certain toxicants in domestic supplies, our results indicate that irrigation water is largely suitable across most of the study area but contains small hotspots of elevated metals that merit follow-up. Careful framing—linking irrigation results to potential long-term risks for soil accumulation and crop uptake, rather than concluding direct equivalence with drinking water hazards—is necessary.

5. Conclusions and Recommendations

This study assessed the status of heavy metal contamination in groundwater in the study area, which is part of the Vehari district in the South Punjab region of Pakistan. Evaluations have been carried out for the drinking and irrigation sectors, which are major consumers of groundwater in the area. The Heavy Metal Index in groundwater as well as in surface water samples and the Heavy Metal Pollution Index were calculated for drinking purposes. Sample No. 15 (five percent of the total samples) was taken from an electric turbine at Mouza Ghulam Qadir in Vehari and was found to be in the excellent class of HPI. HPI’s good classification accounts for 20% of all samples, while 35% were classified as “poor” by the HPI. Sample number 5 was retrieved from an electric tubewell in Chak no. 85/WB, sample number 6 from an electric turbine at an Agri Seed Farm, and sample number 19 from an electric turbine in Chak no. 45 3/EB. The HP Index indicates that 25% of total samples are unsuitable for human consumption. The use of groundwater for drinking has been deemed dangerous if the HPI value exceeds 100. According to this index, 20% of all samples fall into the moderately affected category. Furthermore, 20% of the overall sample is strongly affected, while the remaining 60% of the samples fall into the seriously affected category. The use of groundwater for drinking has been deemed dangerous when the Heavy Metal Index exceeds six. Drinking contaminated water is among the major causes of mortality and many severe diseases in many developing countries like Pakistan [33].

Surface water was also classified for drinking purposes using the HPI and HI indexes. It is also compared to the average of the groundwater sample average. The average of the ground water samples and the drain sample fall into the extremely bad category of HPI for drinking. Canal and river water samples, on the other hand, are in the bad class of HPI for drinking. For drinking purposes, the samples were additionally categorized using the Heavy Metal Index. According to the HI results, all of the samples are classified as seriously affected. As such, both the surface and groundwater in the study area are not fit for drinking purposes.

Groundwater samples were tested against the approved Maximum Permissible Irrigation Limits. Aluminum (Al), Cadmium (Cd), Cobalt (Co), Chromium (Cr), Copper (Cu), Nickel (Ni), Lead (Pb), Selenium (Se), and Zinc (Zn) were all found to be 100 percent within permissible levels; however, 75 percent of the samples with respect to Barium were not fit, while 15% of groundwater samples containing Arsenic and Molybdenum are inappropriate for irrigation according to approved maximum acceptable concentrations. Surface water samples were taken from various water bodies, including one from a drain, one from a canal, and one from a river. The drain sample with the parameters (heavy metals) Al, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, and Zn fit within the acceptable irrigation limit. The results for the canal sample with the parameters (heavy metals) Al, As, Ba, Cd, Co, Cr, Cu, Mn, Mo, Ni, Pb, Se, and Zn are all under the permitted irrigation limit. Similarly, river samples were examined to determine the maximum allowable limit for irrigation purposes, which were found fit.

Therefore, it is recommended that groundwater may not be used for direct human consumption in the study area. However, groundwater is still usable for irrigation purposes and needs proper protection before it is too late. If the present level of industrial and agricultural development continues and effluents continue to be thrown untreated into water bodies, the pollution level of aquifers may rise. The managed aquifer recharge (MAR) project of the Punjab Government in the area seems to be feasible, as groundwater and surface water in the area are still fit for irrigation. More than 90% of extracted groundwater in the area is consumed by the agriculture sector. As such, recharging the aquifer using surplus flood water looks justified. Further, surface water of the river and canal is also fit for irrigation. This supports the concept of MAR using surplus water from the Islam Headwork from the Sutlej River.

On the basis of this research, it has been found that exceedances were limited in frequency and were random; therefore, management should prioritize (i) targeted monitoring of identified hotspots, (ii) assessment of soil and crop uptake in affected areas, and (iii) source control (e.g., preventing industrial or wastewater discharge into irrigation supplies). For policy purposes, distinguishing irrigation suitability from potable-water safety is essential; each requires separate monitoring and mitigation strategies.