Water Supply, Sanitation, and Irrigation in Vega Alta (Murcia, Spain)

Abstract

Climate change is projected to significantly reduce water availability, particularly in arid and semi-arid regions, which makes hydrological planning essential given the increasing competition for water resources. Inefficient consumption patterns exacerbate water depletion and highlight the importance of water quality management. Promoting sustainable practices, reducing consumption, and enhancing water recycling contribute to a more resilient approach. The aim of thIS study is to evaluate the reuse of reclaimed water in the Vega Alta region, which accounts for almost 15% of the total water mix (about 99 hm³/year) as it reuses 92.52% of the treated wastewater, most of which is pumped to irrigation areas targeted for consolidation, also creating new landscapes. These figures place the Region of Murcia as the leading autonomous community in Spain for water reuse, although challenges remain regarding water volumes and the associated costs, investment, and maintenance.

1. Introduction

Climate change projections show a significant reduction in the availability of water resources [1]. Particularly, in arid and semi-arid regions, competence over water resources for different uses, such as potable, irrigation, industrial, and others, poses an urgent need to reevaluate hydrological planning and the pool of the water mix. In this context, circular economy stands as a crucial strategy for addressing the challenges associated with water scarcity [2]. In dry areas, the limited availability of water resources is exacerbated by linear and inefficient consumption patterns, which not only deplete freshwater reserves and require the presence of new water resources such as desalination, but also drives special attention towards pollutants and water quality [3,4]. Water supply improvements in terms of distribution performance avoiding water loss or non-revenue water are required [5], but that should be carried out in parallel to implementing circular economy principles in water management such as reducing consumption through energy-saving technologies [6], promoting sustainable production and consumption practices, promoting the recycling of water, and repurposing water management models, such as the wastewater use basin [7], present an opportunity to break away from the linear exploitation model and move toward a more regenerative and resilient approach [8]. In this approach, reclaimed water can contribute to achieve a sustainable balance between demand and supply [9]. It is regarded as the most economic non-conventional resource, cheaper than desalination [10]. However, concerns over salinity, emerging contaminants, and lack of institutional coordination still affect the reuse of water [11]. In addition, water reclamation is a limited resource, as the maximum amount of treated water will never exceed the corresponding volume of supplies and water collected after heavy downpours in unitary systems, which could accumulate in storm tanks and subsequently be treated in sewage treatment plants [12,13]. Moreover, water sanitation and the supply of reclaimed water for reuse generate costs. There is a debate on who should bear the investment in tertiary treatment (civil works and their financial costs), and the operating and maintenance costs, with the potential users being the most suitable [14].

Among the antecedents of water reuse in southeastern Spain, there is a long history dating back more than 800 years to the Segura River plain in the pre-coastal depression, where a complementarity (symbiosis) exists in irrigation and drainage cultural practices between the ‘alive’ water network (dams and irrigation ditches that supply water for irrigation) and the ‘dead’ water network (escorredores and azarbes, small channels that carry the excess or leftover water). The water from drainage is again used to irrigate lands topographically located at lower elevations, these being in the Lower Segura Valley [15]. An example of this reuse (drainage–irrigation) is the Azarbe Mayor del Norte system in the Huerta de Murcia, which continues along the Mancomunado riverbed as an irrigation ditch in the Huerta de Orihuela [16]. By reusing water repeatedly, as it occurs in its natural cycle, a circular water economy is generated [17].

In southeastern Spain, non-conventional resources (regeneration and desalination) are contemplated in the 2022–2027 hydrological planning of the Segura Hydrographic Demarcation (DHS), not only as complementary resources, but as strategic resources and even as a guarantee of water insurance [18]. The case study of Vega Alta (region of Murcia) is of great interest as it involves the leading autonomous community in water reuse in Spain, called the ‘benchmark’ ahead of Valencia or the Spanish islands [19]. Out of the 15 municipalities that compose the Vega Alta area, this study focuses on three: Cieza, Abarán, and Blanca, these three being the core of the region. In Cieza and Blanca, primary water supply (catchment) is carried out by the Commonwealth of Taibilla Channels (MCT), and secondary water supply (distribution to users) is carried out by municipal companies. In Abarán, water comes from diverse sources, relying on a drainage gallery in Sierra del Oro (Fuente de Benito gallery), a Water Treatment Plant (WTP) next to the Segura River, which provides more than half of its consumption, apart from the volumes supplied by the MCT. All three municipalities direct their wastewater to different Sewage Treatment Plants (STPs), where it receives three treatments (primary, secondary, and tertiary), regenerating the water for other uses (85% for irrigation) in a circular water economy in which it constitutes an unconventional water resource. The research objective is to analyze the state of water supplies and the reuse of reclaimed water as a resource for other users, including irrigation communities (ICs), highlighting its potential to guarantee water consumption for subsequent uses such as irrigation. This study also examines the impact of water treatment plants (WTPs) that make water potable and sewage treatment plants (STPs), including pumping stations, storage tanks, etc., which create new landscapes.

2. Materials and Methods

This is a study of Regional Geographical Analysis, diachronic, with qualitative research within the paradigm of water resources supply for arid and semi-arid regions, where treated sewage can be a complement of extraordinary social and economic value.

The methodology followed consists of a bibliographic search to frame the background and status of the reuse of water. In order to obtain technical advice, meetings were held with experts in charge of the management of recycling and sanitation, with later visits to the WTPs and STPs, and with experts of those irrigation associations which use reclaimed water. These consultations allowed us to record the distribution of water resources and the role of reclaimed water in the water mix of several irrigation communities.

Research work also included the collection of information of the volumes supplied by the Commonwealth of Taibilla Channels (MCT) and other water supply stakeholders, such as water municipal companies. Regarding the information of treated and reclaimed volumes, it was collected from the Wastewater Sanitation and Treatment Authority of the Region of Murcia (ESAMUR), whereas the information related to the reclaimed water authorizations was provided by the Segura River Basin Water Commissioner’s Office in the DHS. Research work finally included the writing of conclusions and proposals, with the aim of highlighting the value of this management model and spreading it to other arid and semi-arid regions.

3. Area of Study

The area of Vega Alta, located in the province of Murcia, Spain, comprises the stretch of the Segura River from the outlet of the Cenajo reservoir (specifically from the Del Rey diversion dam, in the Los Caballos Strait) until the Las Pudingas Strait, where the Contraparada diversion dam is located, which is the main weir for irrigation in the Vega Media (also known as Huerta de Murcia) [15]. The Murcian municipalities crossed by the Segura or close to the river course are Moratalla, Calasparra, Cieza, Abarán, Blanca, Ojós, Villanueva, Ulea, Ricote, Archena, Alguazas, Ceutí, Lorquí, Las Torres de Cotillas and Molina de Segura (

Table 1. Population of the Murcian municipalities of the Vega Alta (comparison between 2000 and 2023).

Municipality	Surface (km2)	Population 2000	Population 2023	Difference	% Difference
Moratalla	954.82	8460	7588	−872	−10.31
Calasparra	184.90	8888	10,161	1273	14.32
Cieza	367.02	32,126	35,286	3160	9.84
Abarán	114.94	12,241	12,964	723	5.91
Blanca	87.32	5749	6756	1007	17.52
Ojós	45.28	593	539	−54	−9.11
Villanueva	13.18	1528	3771	2243	146.79
Ulea	40.04	959	874	−85	−8.86
Ricote	86.67	1582	1240	−342	−21.62
Archena	16.40	14,516	20,110	5594	38.54
Alguazas	23.74	7052	10,218	3166	101.62
Torres de Cotillas	38.78	16,003	22,183	6180	38.62
Ceutí	10.25	7305	12,668	5383	73.69
Lorquí	15.75	5562	7706	2144	38.55
Molina de Segura	169.50	44,389	76,074	31,685	71.38
TOTAL Vega Alta	2168.59	166,993	228,138	61,145	36.62
TOTAL Reg. Murcia	11,313.11	1,184,116	1,552,457	368,341	31.11
% V.Alta/R. Murcia	19.17	14.10	14.70	-	-

Source: prepared by the authors using data from the INE (National Institute of Statistics and Census). Municipal Population Register.

). It is worth mentioning that most of Moratalla municipality is far from the Segura River; only El Salmerón district is riverside and linked to the Calasparra rice reserve. In the remaining municipalities, their municipal boundaries only exceed 100 km² in the cases of Calasparra, Cieza, Abarán, and Molina del Segura.

In most of the regional divisions, the municipalities of Moratalla and Calasparra make up the Northwest Region, along with those of Caravaca, Cehegín, and Bullas. In the regionalization of Calvo & Fuentes [20], which was assumed by the Autonomous Community of the Region of Murcia (CARM), the term ‘Vega Alta’ was adopted for the region formed by the municipalities of Cieza, Abarán, and Blanca, which comprise an area of 569.28 km² and a population of 55,006 inhabitants.

Vega Alta, in the broader sense of the 15 municipalities, has experienced a population increase in the 21st century (61,145 inhabitants, or 36.62%). However, some municipalities have lost population, such as Ulea (−8.86%), Ojós (−9.11%), and Ricote (−21.62%), all of them municipalities in the Ricote Valley, with a predominantly agricultural economy. These municipalities are traditionally irrigated, either from springs and wells, as in the case of Ricote, or from the Segura basin, as in the case of Ojós and Ulea. Both industry and service sectors are very limited, and these activities are mostly located in nearby municipalities such as Archena and Molina de Segura, which rely on more industrial diversification (plastics, irrigation materials, cardboard boxes, canning factories, etc.); above all, these are large service centers (such as logistics and transportation). Moratalla is located in the Northwest region, where dryland agriculture predominates and there is little industrialization, making it a land of migration. By contrast, in the municipalities of Cieza, Abarán, and Blanca, there has been positive growth in the period of 2000–2023, with 4890 inhabitants, with increases of 5.91% in Abarán, 9.84% in Cieza, and 17.52% in Blanca, areas with a dynamic primary sector that also stimulates industrialization and the service sector.

The majority of the water supply volumes for this population are provided by the MCT. Water consumption averaged 15.40 hm³/year for the 2020/21, 2021/22, and 2022/23 hydrological years, representing 7.68% of the total volume distributed by the MCT, which is approximately 200 hm³/year (

Table 2. Volumes of water (in m³) received from the MCT in the hydrological years of 2020/21, 2021/22 and 2022/23 in the municipalities of Vega Alta.

Municipality	2020/21 (m3)	2021/22 (m3)	2022/23 (m3)	Average (m3)
Calasparra	1,022,510	1,017,653	1,019,859	1,020,007.33
Cieza	1,804,095	1,825,070	1,817,105	1,815,423.33
Abarán	334,304	350,732	358,385	347,807.00
Blanca	518,725	497,931	532,219	516,291.67
Ojós	71,138	83,852	84,083	79,691.00
Villanueva	242,115	247,683	250,839	246,879.00
Ricote	156,545	146,556	151,327	151,476.00
Ulea	81,252	91,216	76,311	82,926.33
Archena	1,392,746	1,447,809	1,428,724	1,423,093.00
Alguazas	852,028	924,099	963,848	913,325.00
Torres de Cotillas	2,062,033	2,083,209	2,139,861	2,095,034.33
Ceutí	916,744	977,991	942,918	945,884.33
Lorquí	613,461	610,538	645,226	623,075.00
Molina de Segura	5,105,165	5,209,075	5,190,361	5,168,200.33
TOTAL Vega Alta	15,172,861	15,513,414	15,525,391	15,403,888.66
TOTAL MCT	195,977,447	197,889,603	207,799,877	200,555,642.33
% Vega Alta/MCT	7.74	7.84	7.47	7.68

Source: prepared by the authors using data from the Commonwealth of Taibilla Channels (MCT).

). The municipalities of Cieza, Abarán, and Blanca received an average volume of 2,679,522 hm³ from the MCT during the 2020/21, 2021/22, and 2022/23 periods, representing 1.34% of the total volume distributed by the MCT.

In the case of the municipality of Abarán, the source of the water is more diversified. In addition to the volumes of water purified by the MCT in the WTPs of Sierra de La Espada, and Letur, Abarán also has its own municipal water treatment plant that draws water from the Segura River in the Las Canales area (in Las Norias Park). The Virgen del Oro neighborhood, on the right bank of the Segura River, is also currently supplied with potable water from the traditional source of Fuente de Benito (groundwater collected through a water mine in Sierra del Oro, about 3 km from the town of Abarán) [21]. In the period of 2010–2023, regarding the origin of the water for supply in the municipality of Abarán, more than half (55.10%) corresponded to that produced at the Segura WTP in Abarán, just over a third (36.12%) to the volumes supplied by the MCT, and the remainder (8.78%) to water collected at the Fuente de Benito water mine.

Regarding per capita consumption in the ‘greater’ Vega Alta, in the 2022/2023 hydrological year, the lowest figure was noted in Cieza, with 51.50 m³/inhabitant per year, and the highest one in Ojós, with 156.00 m³/inhabitant per year. The average for Vega Alta was 74.39 m³/person/year. In the 2023/2024 hydrological year, slightly more water was consumed in the Vega Alta as a whole (920,283 m³/year). Cieza remained the lowest in terms of m³/person per year, and Ojós the highest.

Figures from MCT show that per capita consumption has risen from 197,889,603 m³ (2021/22 hydrological year) to 202,799,877 m³ (2022/23) and 215,594,777 m³ (2023/24), which represents an increase of more than 6% (

Table 3. Volume of water supplied (m³) and per capita consumption (m³/person) in Vega Alta, hydrological years 2022/2023 and 2023/2024.

Municipality	Hydrological Year 2022/2023		Hydrological Year 2023/2024
	Total Volume Consumed (m3)	Per Capita Consumption (m3/year)	Total Volume Consumed (m3)	Per Capita Consumption (m3/year)
Moratalla	763,550	100.63	836,921	108.98
Calasparra	1,019,859	100.37	1,140,611	112.25
Cieza	1,817,105	51.50	1,858,733	52.68
Abarán	964,562 *	74.40	1,056,827 **	81.52
Blanca	532,219	78.78	524,524	77.64
Ojós	84,083	156.00	74,782	138.74
Villanueva	250,839	66.52	282,644	74.95
Ricote	151,327	122.03	166,364	134.16
Ulea	76,311	87.31	78,031	89.28
Archena	1,428,724	71.04	1,418,072	70.52
Alguazas	963,848	94.33	1,004,702	98.33
Torres de Cotillas	2,139,861	96.46	2,285,126	103.01
Ceutí	942,918	74.43	991,724	78.29
Lorquí	645,226	83.73	685,164	88.91
Molina de Segura	5,190,361	68.23	5,496,851	72.26
TOTAL Vega Alta	16,970,793	74.39	17,891,076	78.42

* Abarán consumed 358,365 m³/year of MCT. ** Abarán consumed 456,650 m³/year of MCT. Source: prepared by the authors using data from (MCT) and the Abarán Municipal Water Company.

).

4. Water Circular Economy in Vega Alta

In the Region of Murcia, from 2003 to 2023, the average amount of treated sewage was 107 hm³/year, out of which approximately 99 hm³/year was reused, meaning 92.52%, thus making it the leading autonomous community in Spain in terms of reuse, followed by the Balearic Islands and the Valencian Community.

Among the STPs located in the Vega Alta region, the most notable for their treated volumes (average for the three-year period of 2021, 2022, and 2023) are Molina de Segura Norte (6,541,854 m³/year), Cieza (2,409,103 m³/year), Archena (1,865,737 m³/year), and Las Torres de Cotillas (1,593,471 m³/year). In the three-year period of 2021, 2022, and 2023, the STPs located in the Vega Alta region treated an average volume of 17,397,184.33 m³/year, i.e., 14.93% of the total volume treated in the Region of Murcia (

Table 4. Main STPs in the Vega Alta region and volumes treated.

STP	2021 (m3)	2022 (m3)	2023 (m3)	Average (m3)
Calasparra	665,846	683,461	663,220	670,842
Cieza	2,527,145	2,437,937	2,262,226	2,409,103
Abarán	708,433	746,252	648,968	701,218
Blanca	364,796	364,713	330,028	353,179
Archena (*)	1,889,253	1,961,090	1,747,869	1,865,737
Alguazas	1,238,589	1,346,175	1,288,592	1,291,119
Ceutí	1,149,936	1,232,938	1,331,363	1,238,790
Lorquí	1,003,781	1,128,116	1,025,476	1,052,458
Molina de Segura Norte	6,555,047	6,868,075	6,202,440	6,541,854
Las Torres de Cotillas	1,560,037	1,689,102	1,531,275	1,593,471
Pol. Industrial T. Cotillas	28,118	34,009	22,187	28,105
TOTAL Vega Alta	16,646,041	18,491,868	17,053,644	17,397,184
TOTAL Region of Murcia	113,830,940	120,836,185	114,973,329	116,546,818
% Vega Alta/Region of Murcia	14.62	15.30	14.83	14.93

(*) Archena STP also treats sewage coming from Ojós, Villanueva, Ulea, and Ricote. Source: prepared by the authors using ESAMUR data.

).

Reclaimed water is intended to consolidate and replenish irrigation systems, as well as to maintain green areas in gardens and golf courses. The most notable uses include:

-

In Cieza STP (use #3792, as listed by the DHS), a volume of reclaimed water of up to 1,150,000 m³/year is available to complete the irrigation of 1338.70 hectares in the North Central Board of Las Vegas del Segura, for the Irrigation Communities of Acequia de Los Charcos and La Serrana-Los Albares. The concession date is 3 March 2000.

-

In Abarán STP (use #5152) up to a volume of 1,350,000 m³/year is used to consolidate the irrigation of 838.00 hectares of the Casablanca Irrigation Community. The concession date is 6 February 2006.

-

In Blanca STP, up to 450,000 m³/year is used to complete the irrigation of 2915.10 hectares of the Irrigation Community of Zone II, of the Upper and Middle Vegas del Segura (Blanca Sector). The concession date is 27 September 2005.

-

In Archena STP, up to 1,330,810 m³/year is used to consolidate the irrigation of 1635.61 hectares. The concession date is 21 December 2018.

-

In Alguazas STP, use #7773, up to 1,259,617 m³/year is used to consolidate the irrigation of 1368.69 hectares; and use #7774, with up to 645,478 m³/year, is used for the irrigation of 152.20 hectares. The concession date for both authorizations is 11 July 2012.

-

Ceutí STP (#6191), with up to 843,273 m³/year, irrigates 461.57 hectares. And #6192, with up to 860,535 m³/year, irrigates 418.00 hectares. The concession for both uses was granted on 18 July 2007.

-

Lorquí STP (#6193), with up to 1,233,792 m³/year, to complete the irrigation of 461.57 hectares. The concession date is 18 July 2007.

-

In Molina de Segura Norte STP, in addition to addressing the environmental use of the Campotéjar lagoons, up to 4,510,989 m³/year are allocated to consolidate 5587.31 hectares of irrigated land. Up to 101,789 m³/year are also used to irrigate 45.20 hectares of gardens in the municipality of Molina de Segura, and up to 400,000 m³/year for gardens and a golf course located in Altorreal.

-

In Las Torres de Cotillas STP (#8095), up to 1,432,900 m³/year are allocated to irrigate 1635.61 hectares in Zone V of the Tagus-Segura Transfer (Sectors I and II). The concession date is 24 June 2014.

STPs are generally located in lower terrain than the irrigated areas and the water resources they must serve. To obtain access to this reclaimed water, pumping operations are required, which have high energy costs. The Regional Ministry of Water and Agriculture (CARM) provides support for this type of pumping infrastructure within its Rural Development Programs. In 2016, an investment of EUR 778,285 was planned to pump up to 1,432,900 m³/year of reclaimed water from Ceutí STP to replenish the Irrigation Community of Zone V of the Tagus-Segura Transfer (Sectors I and II). For its part, the same Irrigation Community also received aid in 2021 for a planned investment of EUR 600,000 to connect with the Ceutí STP and obtain up to 1,330,810 m³/year of reclaimed water. In 2021, aid was also granted for an investment of EUR 600,000 to supply the Irrigation Community of Zone I of Las Vegas Alta and Media (Calasparra-Cieza) with reclaimed water from Calasparra STP, providing up to 590,434 m³/year.

Irrigation is the main use benefiting from reclaimed water in the Region of Murcia (more than 85% of the volumes). This is also evident in Vega Alta, where several irrigation communities include reclaimed water among their resources. The average share of reclaimed water in the mix of irrigation communities included in

Table 5. Share of reclaimed water in the water resource mix of several irrigation communities in Vega Alta.

Irrigation Communities	Reclaimed Water (m3)	Total of Water Resources (m3)	%
La Serrana-Los Albares (Cieza)	1,150,000	8,079,200	14.23
Casablanca (Abarán)	606,000	4,093,000	14.81
Zona IIª Vegas Alta y Media (Blanca)	382,572	8,544,132	4.48
Heredamiento Regante de Molina de Segura (Lorquí, Molina de Segura)	2,200,000	14,462,956	15.21
Heredamiento de Aguas de Alguazas	680,000	7,776,505	8.74
Zona V Sectores I y II (Ceutí, Las Torres de Cotillas)	445,254	4,299,750	10.36
Total	5,463,826	47,255,543	11.56

Source: prepared by the authors, based on data from the irrigation communities.

was 12.12%.

4.1. Sewage Treatment at Cieza STP, and Use of Reclaimed Water in the Irrigation Communities of Acequia De Los Charcos and La Serrana-Los Albares

Cieza STP (Figure 1) consists of a pretreatment and pumping station in the Gramalejo area, on the left bank of the Segura River, and a prolonged aeration activated sludge treatment plant (biological) with tertiary regeneration treatment using ultraviolet light, located in the Realejo area. It receives sewage from the urban center of Cieza and the district of Ascoy, as well as from the industrial parks of Ascoy and Los Prados.

At the lowest point of the Cieza basin is the sewage pumping station, where the water line begins, with solid removal, degreasing, and sand removal. It has a lamination tank and pumping station, from where the water is pumped to the biological treatment plant (STP), located 2.7 km away, where tertiary sewage treatment, sludge treatment, deodorization, and other processes are carried out.

The STP was built in 2001, with a designed inflow of 47,898 population equivalents and a population of 83,300 h.e., placing it 28th among STPs in the Region of Murcia and 229th in Spain as a whole. Initially, it only had primary and secondary treatment, as well as nitrogen and phosphorus removal; tertiary treatment was implemented in 2010. The Cieza Sanitation Master Plan (2016) reflected that the hydraulic structure was largely unitary (sewage and stormwater were not separated), and this remains the case. Therefore, the STP also treats stormwater collected by the Cieza sewershed system.

Since its construction at the beginning of the 21st century, it has undergone significant modifications to improve its facilities and treatment systems (including energy-saving measures and equipment). In September 2017, the biological treatment plant was remodeled, resulting in 15% energy saving. In November 2024, the tertiary treatment plant was upgraded with advanced filtration technology, and energy optimization measures (solar panels, power inverters, etc.) have continued.

More than 2 hm³/year are treated at a rate of 6000 m³/day. In 2023, 2,143,533 m³ were received, and 100% were treated. Out of these volumes, almost 1.5 hm³ are directly reused for agriculture, and the remainder is sent to the public water domain, in this case, to the Segura River (indirect reuse). Management is carried out by ESAMUR through a joint venture of companies (URDECOM, SAV, and DAM) specialized in these tasks.

In Cieza, two irrigation communities (Acequia de Los Charcos and La Serrana-Los Albares) can have up to 1,150,000 m³/year of treated water at Cieza STP; both irrigated areas are located on the left bank of the Segura River. The historically irrigated area, used for water flowing through the Acequia de Los Charcos-Fatego, is shrinking due to the urban expansion of Cieza, which occupies irrigated and even flood-prone areas. This is a traditional irrigation system, with gravity irrigation, mainly used for vegetables and root crops, and some citrus and prunus trees; these crops are geared toward supplying a local, nearby market.

As of 31 December 2023, the number of irrigators was 245, and the irrigable area was 231.25 hectares. Almost all farms were small, under 1 hectare: microfarms and part-time farming predominate. Over the last five years, the average irrigation consumption was 1,268,866 m³/year (almost entirely from the Segura River basin’s local resources, as reclaimed water from Cieza-Los Charcos STP is barely used). In the 2023/24 hydrological year, the drought experienced in the Segura River Basin forced a reduction in consumption to 563,000 m³/year, i.e., almost half of a situation without shortages (it was only 44.37% of a normal year).

The La Serrana-Los Albares Irrigation Community is more recent: on 25 February 1998, the Agricultural Processing Company (APC) 3470 Los Albares and APC 3472 La Serrana merged to form the La Serrana-Los Albares Irrigation Community. Irrigation is carried out with groundwater resources from the Ascoy-Sopalmo Aquifer (three wells in the Canutos area) and water from the Segura River. In the Los Albares Reservoir (40,000 m³ capacity), reclaimed water from Cieza STP is received by gravity and mixed with the other waters in a 1/3 ratio. The irrigated area is located above the elevation of the Los Charcos-Fatego irrigation canal and the A-30 motorway. The eastern sector is delimited by the Rambla del Moro riverbed.

The irrigated area, as of 31 December 2023, was 1341 hectares, divided into 764 cadastral plots. The community was made up of 450 community irrigators. Regarding the productive orientation of the irrigated area, the majority (1186.50 hectares) is dedicated to stone fruit trees, representing 88.48%. More than three-quarters of the volume consumed for irrigation comes from groundwater (79.22%), from reclaimed water (14.33%), and from the Segura River (6.55%). In the 2024/2025 campaign, there was a reduction in irrigation water consumption due to the drought in the Segura Basin (in October 2024, the volume of water stored was below 15% of the basin’s reservoir capacity). These are modernized irrigation systems, equipped with drip irrigation systems owing to more than 150 km of main pipelines, which distribute water to the storage and regulation reservoirs, located at elevations that allow sufficient gravity pressure to reach the irrigation sectors and plots.

The altitude of the irrigated area (the foothills of the southeastern slope of the Ascoy mountain range and the surrounding area of the small mountains of Morrón) requires water pumping, as well as storage and regulation reservoirs for pressurized irrigation, with high energy consumption. The Irrigation Community has 11 reservoirs with a capacity exceeding 670,000 m³. The highest irrigated area receives water from the Canutos Pumping Station to the “Sierra” reservoir (35,000 m³). From the “Canutos” reservoir (200,000 m³), water is sent to the upper and middle irrigated areas, which receive water from the Canutos Pumping Station and the Principal Pumping Station from Los Albares. The lower irrigated area and the Morrón irrigated area also receive water from the Principal Pumping Station.

The average energy consumption for the 2020–2023 period was 1,873,688 kWh, at a cost of EUR 179,954. Of the three pumping stations, the Albares pumping station had the highest consumption (46.08%), followed by the Canuto Well pumping station (39.46%), and the Gramalejo pumping station (14.46%). Therefore, the Ministry of Agriculture, Fisheries, and Food allocated EUR 6.3 million for the installation of a self-consumption solar photovoltaic plant with no surplus discharge. On 23 October 2023, an agreement was signed between the State-owned Agricultural Infrastructure Trading Company (SEIASA) and the Irrigation Community within the framework of the Recovery, Transformation, and Resilience Plan for actions to modernize sustainable irrigation systems, use renewable energy, reuse reclaimed water for irrigation, and introduce tools for the digitalization of irrigated agriculture. Part of the solar photovoltaic park is located in the watershed of the Balsa Albares reservoir. These facilities are complemented by a battery storage system that will enable the storage of the energy produced and supply it to the pumping system 24 h a day. In addition, the Irrigation Community plans to build two more photovoltaic parks within its irrigated area, which would reduce the cost to irrigators from EUR 0.35 per cubic meter to less than EUR 0.10 per cubic meter.

4.2. Use of Reclaimed Water for Irrigation in the IC Casablanca (Abarán), and IC of Zone II of Las Vegas Alta and Media (Blanca)

The IC Casablanca, based in the Vergeles area of Abarán, has an irrigated area of 838 hectares, most of which is used for the cultivation of grapes and stone fruits. As of 31 December 2023, the community is made up of 315 irrigation community members, most of whom have farms of less than 1 hectare (41.27% of the irrigators, who account for only 11.69% of the irrigated area). There are no farms larger than 100 hectares in this IC. In the 2019–2023 period, the average water consumption stood at 4,093,000 m³/year, of which 14.81% corresponded to reclaimed water from the Abarán STP, which requires pumping to access this water. In 2024, the IC commissioned a small photovoltaic plant (330 kW) to cover the energy costs of pumping water to the storage and regulation reservoirs, from which water is distributed through a pressurized network.

The irrigated area of the IC of Zone II of the Upper and Middle Vegas del Segura, located in the San Roque area in Blanca, covers an area of 2960 hectares. As of 31 December 2023, the community is made up of 471 community irrigators, most of whom have farms of less than 1 hectare (46.71% of irrigators, accounting for only 3.54% of the area). However, four large farms of more than 100 hectares (0.85% of irrigators) account for 20.23% of the area. As of 31 December 2023, the irrigation water concessions were as follows: up to 5,728,000 m³/year from the Tagus-Segura Transfer, up to 450,000 m³/year of reclaimed water from Blanca STP, up to 5,110,665 m³/year from the Segura River (according to the Decree of 25 April 1953), and up to 2,342,400 m³/year from the desalination plant of Torrevieja. For an average annual volume (consumed in the period of 2016–2023) of 8,544,132 m³, the share of reclaimed water from Blanca STP barely reaches 5% (4.48%) of the total resources used, the reclaimed water concession being up to 450,000 m³/year. To access this water, the company has a pumping station from Blanca STP (with a flow rate of 30 l/sec at a height of 117 m) to the Casa Alcántara reservoir (11,310 m³ capacity). This IC has modernized its management, automation, and control of irrigation water. The Phase IV Modernization Project aims to reduce energy costs by producing 4.0 MW of photovoltaic energy for self-consumption using panels located on water surfaces and reservoir slopes. To provide greater information on crop needs, the company has a network of humidity and nitrate probes, as well as flow meters, pressure transmitters, etc. Concerning the origin of water resources during the 2016–2023 period, the Segura River Basin’s local waters stand out, accounting for more than half of the total (55.16%), which are drawn and lifted from the Segura River, whereas the volume of water from the Tagus-Segura Transfer did not reach a quarter of the total (23.80%). Non-conventional resources (desalination and reclaimed water) accounted for just over 10% (10.29%).

4.3. Reclaimed Water as a Resource for the Molina De Segura Irrigation Estate

The Molina de Segura Irrigation Estate stands out as an example of traditional use of the water from the Segura River. In 1607, 4244 tahúllas (tahúlla is a unit of measurement; 1 tahulla equals 1118 m²) were irrigated, distributed among 216 heirs (participating members of the estate who, after its transformation into an irrigation community, became known as commoners). It draws water from the Segura River, in the district of Algaida (Archena), through a dam or weir and an open irrigation ditch on the left bank. The distribution of water is carried out through the Molina de Segura Irrigation Ditch and the Subirana Irrigation Ditch. Both join at the Torre Alta site, and the final part of the ditch flows into the Churra La Nueva Irrigation Ditch, near the border of the municipality of Murcia.

As of 31 December 2021, it comprises 4239 community members (heirs) for an irrigated area of 1799 hectares. Most of these community members had farms of less than 1 hectare (95.16%), which accounted for 45.31% of the irrigated area. There were no farms larger than 100 hectares. The current irrigated area is 1884 hectares in the municipalities of Archena, Lorquí, Molina de Segura, and Murcia. It is divided into five irrigation sectors. Sector 1 (the largest, 788 hectares) still has 620 hectares of flood irrigation, which represents 33.42% of the total irrigated area. That is, two-thirds of irrigation have already been modernized, using drip irrigation under pressure. It has a maximum annual volume of up to 12,262,956 m³ of the Segura River for irrigation. It also has up to 2.2 million m³ of reclaimed water from Molina de Segura Norte STP, which accounts for more than 15% of the water consumed for irrigation (15.21%).

4.4. Use of Reclaimed Water from the Alguazas, Archena, Ceutí, and Torres De Cotillas STPs. The IC Acequia De Alguazas and IC Cona V, Sectors I and II

As of 31 December 2024, the Alguazas Water Estate comprises 2629 irrigators, an irrigable area of 1300 hectares, and an irrigated area of 1240 hectares. The farm structure shows that more than three-quarters of irrigators (76.07%) had farms smaller than 1 hectare, and they accounted for almost two-thirds of the irrigated area (64.19%). From the Segura River, through the Alguazas Irrigation Canal, it enjoys a concession for a maximum annual volume of 7,096,505 m³. From Alguazas STP, it has a reclaimed water concession of up to 680,086 m³/year, i.e., 9.74% of the total volume available for the 2020–2024 period.

Most of these are micro-properties, where agriculture is practiced part-time and has barely been modernized. Only the Motores Salazar Homeowners’ Association has been modernized, with localized pressure irrigation (drip). The elevated water levels flowing through the irrigation ditch result in significant energy costs, which is why Motores Salazar launched a self-consumption photovoltaic plant in June 2024.

The IC Zone V, Sectors I and II, has been established since 17 March 1997. As of 31 December 2024, it comprises 415 community members and has an irrigated area of more than 1635 hectares, mostly dedicated to the cultivation of citrus trees (orange and lemon trees) and stone fruit trees (peach, plum, and apricot trees). Farms of 1 to 5 hectares predominate in terms of area, while those of less than 1 hectare are the most common. Most of the irrigated land has been modernized. The modernization plan to implement localized pressure irrigation (drip irrigation) was implemented between 2011 and 2013, and more than 75% of community members now use this irrigation method.

The water concessions it has held in recent years are as follows: from the Tagus-Segura transfer system, up to 7,224,838 m³/year; from Archena STP, up to 1,330,816 m³/year; from Las Torres de Cotillas STP, up to 1,432,900 m³/year; and from the Torrevieja desalination plant, up to 600,000 m³/year (desalinated water concession #CSR-16/2019.16).

The circular economy practiced in this IC, with reclaimed water from several STPs, has increased from values of just over 10% (10.36%) between the 2016/17 and 2020/21 hydrological years to more than 20% in years like 2023 and 2024 (

Table 6. Share of reclaimed water in the IC Zone V Sectors I and II of Vega Alta and Media (2016/17–2020/21).

Hydrological Year	Reclaimed (m3)	Total Water Resources (m3)	(%)
2016/17	620,030	3,762,093	16.48
2017/18	474,120	3,472,562	13.65
2018/19	264,044	4,611,292	5.73
2019/20	783,218	5,188,173	15.10
2020/21	84,860	4,464,629	1.90
Average	445,254.40	4,299,749.80	10.36

Source: own elaboration. Data from IC Zone V, Sectors I and II.

). In the last five years (2020–2024), the composition of the water mix shows that the majority of its resources came from the Tagus-Segura water transfer system and the STPs (direct regeneration for irrigation) (

Table 7. Water resources (in m³) consumed by the CR Zone V, Sectors I and II, in the period of 2020–2024.

Source	2020	2021	2022	2023	2024
Tagus-Segura transfer	1,312,688	3,147,379	3,302,326	2,250,058	3,040,699
Reclaimed from STPs	723,218	98,478	233,478	694,433	1,246,625
Groundwater	429,740	0	0	0	0
Desalination	114,167	12,994	17,006	377,456	0
TOTAL	2,579,813	3,258,851	3,552,810	3,321,947	4,287,324
(%) Reclaimed/TOTAL	28.03	3.02	6.57	20.90	29.08

Source: own elaboration. Data from IC Zone V, Sectors I and II.

). In 2021 and 2022, larger transfers from the Tagus-Segura Transfer were available, with higher quality water and at a lower price (EUR 0.18/m³) than desalination (EUR 0.46/m³). Therefore, the 3.5 hm³/year required by irrigation in Zone V will be met, if possible, with transfers and non-conventional resources such as reclaimed water.

5. Discussion

The infrastructure needed to carry out the sanitation tasks, transport and treatment of sewage, turning it into reclaimed water suitable for direct use (such as irrigation) or indirect use (discharge into the public water system), creates the landscape of sewage pumping stations, STPs and ponds for accumulating reclaimed water (Figure 2). These ponds are then located within or near irrigated areas, thus replenishing certain irrigated areas with these new water resources. Treatment processes and pumping consume energy resources and generate pollution (greenhouse gases) into the atmosphere; therefore, the focus is on self-consumption of renewable energy sources such as photovoltaics. Solar panels are installed on the roofs of facilities, on the slopes and water levels of ponds, and even small photovoltaic parks are increasing next to sewage pumping stations and STPs (Figure 3).

Public administration and society on the whole push for climate change adaptation and the wise and efficient use of resources, even more so in an area of historical struggle for water. Research on water technologies and innovation in irrigation techniques in crops is encouraged, and the results show leadership in the reuse of water and efficiency. However, water governance and social perception remain challenges that need to be addressed [22]. There is currently a debate about whether the investment and operating costs inherent in the production and supply of reclaimed water should be shared equitably, through the appropriate or established legal formula, between urban or general water users and the final users of reclaimed water. This cost sharing would be based on “the polluter pays” principle for sewage users and on the availability of new water resources for direct reuse users, such as irrigators. In a free market, it would be possible for reclaimed water consumers (irrigators and others) to assume the cost of the increased water resource (volumes of reclaimed water) in order to have an additional amount of water available for their use. The reality is that in regions such as Murcia (with extensive experience in treatment and reuse), sanitation users bear the entire maintenance cost of STPs (primary, secondary, tertiary, and even “quaternary” treatment in the sewage tariff), while irrigators bear the cost of distributing the reclaimed water (pumping, storage tanks, etc.). It is a mechanism that intends to activate an economic “compensation” in terms of water between the city and the countryside for the use of treated waters in the rural environment [23]. Moreover, it is essential to anticipate climate change effects and the availability of water. In the context of ecological transition, although reuse of water is promoted, there are factors that determine the acceptance of these non-conventional resources such as costs and quality [24]. As shown in this article, farmers of the Vega Alta region began to rely on these waters, accepting them as a crucial part of the water pool, mainly because of the unavailability of or reduction in other sources (Tagus-Segura transfer), or the high cost that desalination still has. Even if reclaimed water also requires investments, these costs are shared within society; so, irrigators find an opportunity to take advantage of this policy. I is worth mentioning that in this case study of Vega Alta, social and economic pressure is higher due to the drier climate conditions than in other parts of Spain, such as Valencian Community or Balearic Islands, or even Europe.

Sanitation is essential to achieve the sustainable development of rural settlements and their communities [25]. This is of particular interest in rural areas, such as Vega Alta, where there is competence over land and water resources and the need to protect the environment. This combination of avoiding damage to ecosystems (through the treatment of contaminated water) and enjoying a new, non-conventional water resource (reclaimed water) generates a circular water economy, which is of enormous interest in regions and districts where water is scarce, as happens in Murcia and Vega Alta.

6. Conclusions

The studied area (Vega Alta) and the Region of Murcia are models of circular water economy management. The average volume treated in the STPs installed and operating in the Vega Alta region for the years of 2021, 2022, and 2023 was 17,397,471 m³/year, representing 14.93% of the volume of sewage treated in the Region of Murcia, which was 116,546,818 m³/year. The Vega Alta region is increasingly home to small photovoltaic parks and ponds for storing reclaimed water (almost all of which are used to supplement irrigation). From an analysis of the Irrigation Communities that use reclaimed water (approximately 5,463,826 m³) to supplement their water mix of 47,255,543 m³, reclaimed water accounts for more than 10% (11.56%). Between 2003 and 2023, the average volume of sewage treated in the Region of Murcia was 107 hm³/year, of which approximately 99 hm³/year is reused, i.e., 92.52%, almost all of which is directly reused for irrigation.

From 2001 to 2024, there has been little increase in the sanitation fee, which covers the management of STPs (through ESAMUR and collaborating companies specializing in sewage treatment). The nearly 100 hm³/year of reclaimed water is an unconventional resource (with limited growth) of interest to mitigate a time horizon (2027) that will require the Segura River Basin District (DHS) to end much of the overexploitation of aquifers.

Regarding the technology used in its STPs, ESAMUR is constantly innovating its plants. Some plants use quaternary processes to eliminate emerging contaminants, and the resulting resource could even be drinking water. Reclaimed water is a limited resource that depends on the volume of treated wastewater and contributes to water security in southeastern Spain. However, it does not ensure water sufficiency, which is why many irrigation communities have had to resort to desalinated water supplies.