Monetizing Co-Benefits of Nature-Based Sanitation-Constructed Wetlands Using Contingent Valuation Method—Jordan as a Case Study

Abstract

Parallel to the growing evidence about the efficiency of Nature-based Solutions (NbS) in sanitation, there is a growing need to highlight the co-benefits of these solutions compared to conventional alternatives. This study focuses on economically valuing these co-benefits, with constructed wetlands (CWs) examined as a sanitation solution. The contingent valuation (CV) method has been utilized for this purpose, measuring people’s willingness to pay (WTP) and willingness to accept (WTA) CWs as a sanitation solution. Jordan has been selected as a case study due to the country’s preference for sustainable, cost-efficient solutions. By utilizing extended questionnaires at the stakeholder and community levels, this research aims to identify gaps between these groups’ perspectives on CWs. Additionally, this study investigates the main factors affecting communities’ WTP and WTA. The collected data were analyzed using descriptive statistics for the responses, followed by the CV method, and regression analysis to understand the main factors affecting WTP and WTA. The results are intended to guide decision-makers in developing programs that align with community preferences and address gaps in the acceptance of NbS-CWs. The main results found that while stakeholders have concerns about people’s WTA CWs, the community survey revealed that people prefer CWs over conventional solutions. The findings revealed that 78.9% of respondents were willing to accept (WTA) CWs to treat wastewater in their town, but only 33% WTA having CW near their households. Meanwhile, 53.2% were willing to pay (WTP) for CWs in general, while 80.7% are willing to accept (WTP) using CWs to treat greywater at the household level and 56.9% of the respondents are WTP for that.

1. Introduction

The United Nations World Water Development identified that Nature-Based Solutions (NbS) are solutions inspired and supported by nature and that use or mimic natural processes for the improved management of water [1,2]. Therefore, the defining feature of an NbS is not whether an ecosystem used is ‘natural’, but whether natural processes are being used to achieve a water-related objective.

One of the applications of NbS in treating wastewater is treatment wetlands or constructed wetlands (CWs). CWs are natural treatment technologies that efficiently treat many different types of wastewater (domestic wastewater, agricultural wastewater, coal drainage wastewater, compost and landfill leachates, fish-pond discharges, industrial wastewater, textile mills, and seafood processing). CWs can effectively treat raw wastewater to different levels of treatments and can be used as a primary, secondary, or tertiary treatment [2,3,4].

CWs are engineered solutions designed to optimize processes found in natural environments, thus they are considered sustainable and environmentally friendly options for wastewater treatment. In general, research and several studies have emphasized that CWs have low operational and maintenance requirements and a stable performance with less vulnerability to inflow variation [1,2,3,4].

Conventional wastewater treatment systems, while effective, are often criticized for their high construction, operational, and maintenance costs, as well as their significant energy consumption, which raises concerns about their long-term sustainability, particularly in small communities. In contrast, CWs and other NbS offer a cost-effective and sustainable alternative, addressing both environmental and socioeconomic challenges [1,2,3,4]. NbS in general and CWs specifically have been raised and proved their capability as a treatment technology with a valuable role in solving sanitation problems and considered as an appropriate and sustainable sanitation system for different contexts, whether as a main technology or as combined with the conventional technologies [3,5]. In addition to the cost-effectiveness, CWs can provide environmental and socio-economic benefits. Benefits arising from CWs include, besides treatment capacity, the provision of wildlife and habitat diversity, ability for recreational activities (e.g., bird watching), water storage, regulating weather temperatures, and aesthetic upgrade of the surrounding environment, urban or rural [4,6,7]. Recently, these co-benefits are playing a vital role in selecting NbS and CWs as a sustainable solution, especially in the social aspect. Researchers are recommended to consider these co-benefits when selecting and comparing treatment technologies, through providing values for these co-benefits in order to include them under the financial sustainability and to integrate them easily with the circular economy approach [2,8]. But the gap is to identify these co-benefits accurately, and to express them in monetary values, since most of these benefits and co-benefits are usually not market-priced [9,10].

These co-benefits give NbS and CWs added value and advantages over other treatment solutions. People often enjoy nature and green spaces, but at the same time, they tend to view these places and services as unpaid, common ecosystem services for the community [1,3]. On the other hand, the fast ongoing urbanization leads to the minimizing of green spaces and affects the biodiversity in the cities, raising people’s attention to the importance of having green areas, restoring the biodiversity and ecosystem [11]. Nowadays, people are spending their time and money in the countryside and green parks to enjoy nature and aesthetic places. The previous facts might lead to an increase in peoples’ willingness to pay (WTP) to have green places near their living areas and their willingness to accept (WTA) having NbS and CWs close to their premises. Therefore, measuring their WTP and WTA for having CWs is important to evaluate the valuable co-benefits. Consequently, it is important to find a method to give an economical value for the non-market-priced co-benefits of NbS-CWs in order to integrate these co-benefits with the general sustainability, specifically, the social and financial sustainability of NbS and CWs.

Thus, this has motivated the current research to investigate the community WTP and WTA of applying CWs in the field of sanitation and water management in the selected case study. To address the absence of a clear market mechanism, the contingent valuation (CV) method has been used to study people’s WTP and WTA.

This research focused on Jordan. Jordan is ranked as the second poorest country in terms of daily water availability per person. Around 65% of Jordanians are covered with wastewater services, and the treated wastewater covers almost 14% of the Jordanian water budget. The remaining Jordanians are living in remote rural and semi-urban areas in small communities [12,13,14,15]. The objective of the government is to provide wastewater services to these small communities to increase the amount of collected and treated wastewater. However, serving them with centralized conventional engineering facilities is not feasible due to the high cost. On the other hand, CWs-NbS are more feasible economically and more environmentally friendly, with less maintenance [16,17,18,19]. Therefore, NbS and CWs have raised the attention of the Jordanian stakeholders, although several efforts and research have been allocated for integrating NbS in the sector, and stakeholders have several concerns related to people’s acceptance, the local capacities, and the financial concerns. These concerns have led the movement to adhere with the conventional solutions rather than considering new solutions [20,21].

Therefore, the research aims have been extended to understand the differences between the communities’ and stakeholders’ perspectives in Jordan about integrating NbS-CWs in the sanitation and water management sector. This investigation has been extended to understand the community’s knowledge about climate change’s impacts on Jordan and the water availability, their preferences during the implementation of wastewater treatment plants, and other key topics that might impact the WTP and WTA.

This study’s results are expected to guide decision-makers and stakeholders in the water management sector by offering insights into community perspectives on NbS and CWs. The findings explain the community’s willingness to support government initiatives—both financially and socially—in integrating NbS and CWs into sanitation and water management strategies. Additionally, by identifying gaps in community acceptance, stakeholders can design future programs and interventions that address these areas, ultimately enhancing the likelihood of sustainable, socially accepted solutions.

This research provides a foundation for understanding the preferences and concerns that shape community attitudes toward NbS and CWs, as well as the factors influencing these attitudes. These insights can support stakeholders in making informed decisions and tailoring interventions to address community needs effectively, particularly around potential social and financial challenges.

This paper is organized as follows. Section 1 is the introduction and the CV method. Section 2 presents the questionnaire, methodology, and the tools that were used to analyze the data. Section 3 presents the results, and Section 4 presents the discussion.

2. Materials and Methods

2.1. Questionnaire Design and Implementation

After the preliminary assessments and several meetings with stakeholders (government, operators, and community members), it was found that, to ensure a thorough understanding and identify gaps in applying CWs and NbS, two levels of questionnaires were necessary for this study. The first survey targeted decision-makers and experts in the water and wastewater sector (governments, consultants, academics, NGOs, donors, etc.), while the second survey targeted the general community, without requiring a specific background. These two levels of surveys helped identify challenges, levels of understanding, and gaps between the community and expert stakeholders in these sectors; therefore, increasing the understanding of the community WTP and WTP and the main factors affecting them.

The surveys were translated to Arabic, and the translated surveys were checked by three experts and researchers in the field of environmental engineering/water and wastewater. All surveys were pre-tested and redesigned several times to identify the challenges, level of understanding, and time and ease of filling in the surveys.

A pilot survey was conducted to test the questionnaire in the field using ten people. By the end of this stage, the data were processed by a computer system. The result of the pilot survey required some modifications to the formulation of some of the questions that were related to the community WTP. Specifically, the range of the proposed bids was modified.

In this study, the survey targeted a diverse population, including urban and rural residents, individuals from various income levels, and different educational backgrounds, to ensure a representative sample. A mixed-method approach was adopted to minimize the selection bias and maximize the inclusivity.

Google Forms (2022) were used as a software tool and several communication channels were used to disseminate the final survey. Social media, such as Facebook, WhatsApp, Instagram, and LinkedIn were used to disseminate the surveys. Hard-copy posters were prepared and posted in different places, and the poster includes a QR code, which were placed in community centers, bus stations, and public spaces, to reach individuals without regular internet access.

To monitor the representativeness, we tracked the response distribution throughout the data collection phase and identified underrepresented groups. Corrective actions, such as additional outreach in that area, were implemented as needed.

2.1.1. First Level: Stakeholder’s Level

The stakeholders survey contained several questions, starting from an introduction about the research topic and goals, and general questions about the respondent’s information (occupation, organization, background, etc.). The introduction was followed with the following question categories:

• Starting questions about the general conditions and facts about the water and wastewater sector;
• Questions related to using CWs in wastewater treatment;
• Question to scale the benefits of using CWs in treating wastewater;
• Question related to scaling the most possible challenges that might face the application of CWs;
• An open-area question for stakeholders to add their notes and comments.

2.1.2. Community Levels

The survey started with an introduction about the research and the research purpose, and a short description about NbS and CWs with a picture of a CW to help the community in understanding the technology.

The community survey contained several categories of questions:

• Personal information questions, such as gender, age, educational level, etc.;
• General questions about climate change and water scarcity problems to raise the respondent’s attention;
• Question about the sanitation situations of the respondents, and their sanitation knowledge including the required costs for managing wastewater for every respondent;
• Question about the respondent’s knowledge about wastewater treatment technologies with a focus on NbS and CWs;
• Question about the benefits of having CWs to treat wastewater, and their preferences when having CW projects;
• Questions about the disadvantages and challenges of applying CWs;
• Willingness to accept questions and willingness to pay questions of having CWs to treat wastewater and greywater at the household level;
• Questions about the economical evaluation and reuse of the harvested reeds.

In this study, the dichotomous choice model has been selected to ask for the WTA and WTP, and bidding techniques were used for the WTP. The bidding game is a repeated process that tries to bracket the respondent’s maximum WTP by presenting higher values (bids). The bid values and ranges were obtained based on the Jordanian market and judgments of Jordanian stakeholders.

Finally, the community answered questions to prioritize and order the benefits and co-benefits of having CWs-NbS as a wastewater treatment plant. The community also answered questions about their concerns of having CWs-NbS, such as odor problems, insect problems, land issues, etc.

2.2. Tools for Data Analysis

Several statistical techniques were utilized in this study to analyze the collected data using the social statistical packaging system (SPSS). Descriptive statistics were run against all variables to determine the mean, median, standard deviation, and frequencies of data. The percentages and frequencies were used to describe and analyze the responses and the demographic profile of the respondents. Multiple regression was used as a main statistical technique to explore the relationships within the data. Multiple regression is a statistical technique which allows the researcher to assess the relationship between one dependent variable (WTP and WTA) and several independent variables.

The generic form of a multiple linear regression is as follows:

Yi = β₀ + β₁X_i1 + β₂X_i22i + β₃X_i3…β_jX_ij + εi

(1)

where Y is the dependent, X_i1, … X_ij are the independents, β₀ is the constant, β₁…β_j are the regression coefficients, notation i refers to the i-th case in the n sample of observations, j represents number of independent variables, and ε represents an error term [22].

An important objective of regression analysis is to estimate the unknown parameters in the regression model. This process is also called fitting the model to the data. One of these techniques is the method of least squares [22].

In SPSS, the regression analysis calculates a p-value for each of the regression coefficients [22,23]. The p-value indicates if each independent variable affects the dependent variable in a significant/non-significant way. A low p-value (<0.05) indicates that an independent variable that has a low p-value is likely to be a meaningful addition to the dependent variable (WTA and WTP). Equally, a larger p-value suggests that changes in the independents are not associated with changes in the dependent [23].

3. Results and Discussion

The results have been divided into three categories; firstly, a description statistic for the questions, followed by a CV result, and finally, a regression analysis to understand the parameters that affect people’s WTP and WTA for having CWs-NbS.

3.1. Descriptive Statistics

3.1.1. Stakeholders Level

Ninety-seven (97) Jordanian stakeholders have filled in the questionnaire and answered the questions. Descriptive statistics were run against all the variables. The frequency analysis for each question has been analyzed and summarized as the following.

It was found that 52% of the stakeholders were between 31–45 years old, while 29% were older than 45, and the remaining were less than 30 years old. The highest percentage of the respondents works in the governmental field (41.2%), while the second highest percentage works in non-governmental organizations (25.8%), followed by 18.6% from the private sector, while the remaining percentage is distributed between other types of occupations (academia, NGOs, donors, etc.).

Among the stakeholders, 72.2% mentioned that the most used treatment technology is mechanical systems, while 12.4% answered that they do not know the most used technology. Most of the stakeholders (89.7%) were aware that 35% of the Jordanians are not served with sewer network and wastewater treatment plants, while (74.2%) of the stakeholders were aware that the Jordanian government considers treated wastewater in their water budget. All the stakeholders agreed that the sanitation sector needs more sustainable solutions. Most stakeholders (96%) agreed that serving small towns and scattered populations might enhance the reuse of wastewater. A total of 71.1% of the stakeholders trusted that CWs can be used as a main treatment technology while 28.9% had a different opinion. A total of 69.1% of the stakeholders are aware that conventional wastewater treatment systems produce greenhouse gases and contribute to climate change, while 30.9% did not accept that fact. Almost two thirds of the stakeholders (72.2%) believed that CWs have advantages over the mechanical systems, while the remaining did not agree with this point.

The third category of questions was approaching the general benefits of applying NbS-CWs in sanitation. The stakeholders were asked to score seventeen points if they are matching with the application of NbS-CWs in wastewater on a scale from one to five (where one is the least and five is the most).

It was found that 35.1% of the stakeholders strongly believed that CWs have low operational, maintenance, and capital costs, and they gave the highest score for this point, while the second highest percentage for the same point was scored as 3 out of 5 by 28.9% of the stakeholders. The minimum score for this point had a percentage of 2.1%; that means 2.1% of the stakeholders did not agree that the CWs have low operational, maintenance, and capital costs. It was also found that 45.4% of the stakeholders strongly believed that CWs consume zero or limited energy, while the second highest percentage (31%) of stakeholders gave four points for low energy consumption, and only 3.1% gave one point only.

A total of 40.2% of the stakeholders gave five points and agreed that CWs required a huge land area, and 33% of the stakeholders gave four points; from this, we can conclude that the majority of the stakeholders agreed that CWs required a huge land area. For the capacity and skills required, 35.1% of the stakeholders gave four points and agreed that CWs required unskilled labor and operators, while 20.6% of the stakeholders gave five points and the same percentage gave two points only.

Table 1. Summary of final ranking of benefits of having CWs.

Benefits/Point	Ranking
Providing a source of treated wastewater that can be used in agriculture according to Jordanian standards	1
Zero energy or low energy requirements	2
Can be used as a decentralized or semi-centralized solutions for scattered communities and rural area	3
Require less energy and costs to manage sludge and the by-products of treating wastewater	4
Restoring biodiversity and wildlife	5
CWs require huge land area	6
Providing green area and aesthetical places where people can enjoy	6
Generated less sludge and wastes comparing to the mechanical systems	8
Protecting the environment by absorbing the CO2 from the atmosphere	8
Process robustness (avoiding incidents demanding unscheduled manual intervention or unexpected additional cost)	11
CWs can provide a source of financial resources through investment in the harvested reeds and the treated sludge	12
CWs are resilient to climate change impacts (heavy rainfall, heat waves, and flash storms)	13
CWs are a flexible treatment process (greatest ability to handle high variation in water quality and quantity while still meeting treated water quality objective)	14
CWs require unskilled labor and operators	15
Adheres with the legislations and the institutional requirements	16
Can be used as a centralized sanitation solution	17

summarizes the final scoring and ranking of the benefits of having CWs according to the Jordanian stakeholders.

The fourth category of questions for the stakeholders indicated the challenges of applying NbS-CWs in the water and wastewater sector. Stakeholders were asked to score each challenge on a scale from one to five, where one indicated the least possibility while five indicated the maximum possibility of having the challenge.

It was found that 51.6% of the stakeholders strongly believed that the land availability is a challenge for CWs in Jordan (25.8% gave a score of five and 25.8% scored four for this challenge), while only 10.3% agreed that the land availability is not a problem for CWs. While 29.9% of stakeholders had strong concerns about the land costs, 3.1% gave a score of one for this challenge. A total of 35.1% of the stakeholders said that the availability of funding for a new wastewater treatment plant is challenging, with a score of four points, while 29.9% gave a score of five for this challenge. The challenge of the availability of local experiences and skills has very low probabilities according to the stakeholders, since 21.6%, 23.7%, and 27.8% gave a score of 1, 2, and 3, respectively. Among the institutional challenges, 43.3% of the stakeholders agreed that the challenge of unclear responsibilities and ownership availability in the operating of CWs scored four, which indicates a high possibility. Also, 34% of stakeholders thought that accepting CWs by decision makers is a challenge, with a score of four points, while only 8.2% of the stakeholders thought this is not a challenge.

Technically, 39.2% of the stakeholders scored three points for the variability of the treatment efficiency according to the climate and seasons, while 30.9% and 14.4% believe that it can be a challenge with a score of four or five points, respectively. This might give an indication of the lack of knowledge and absence of similar examples of CWs in the country. Regarding the meeting of the reuse standards, the highest score with 36.1% of stakeholders believe this can be a challenge, while 10.3% of the stakeholders thought that it will not be challenging for CWs to meet the reuse Jordanian standards.

From the social point of view, 34% of the stakeholders gave four points, and 24.7% gave five points, which indicated a strong challenge for the social acceptance of CWs; 34% of the stakeholders thought CWs can be a source of odor, with a score of four points, and 39.2% thought CWs are an attractive place to insects and mosquitos. These high scores justified the stakeholders’ concerns about the social acceptance of CWs.

Table 2. Summary of the final ranking of challenges of having CWs.

Challenge	Ranking
The institutional situation and the unclear responsibility for ownership and operation of the plants	1
Availability of funding for a new wastewater treatment plant	2
Availability of funding for operating or availability of an investment scenario in operating similar technology	3
Source of insects and mosquitos	4
The land costs in Jordan	5
People’s acceptance of this technology and preferring mechanical treatments	5
Acceptance of using this technology as a main treatment technology by decision makers	7
Source of odor	8
The variety of treatment efficiency, according to the climate, season, and wastewater characteristics (quality) and quantity.	9
The availability of land	10
Achieving the treatment efficiency standards and reuse standards	11
Managing of sludge and the harvested reeds of the CWs	12
Constructed wetlands need water to be available in the beds all the time within the treatment plants	13
Clogging problem within the filter materials leading to overflow of untreated wastewater	14
The willingness of the private sector to invest through operating constructed wetlands	15
Availability of local experiences and skills in designing similar technology	16
Availability of skills in operation and maintenance of CWs-NbS	17
Local and international donors do not support and fund similar technologies and prefer the mechanical solutions	18
Availability of similar examples in the country that used CWs as a main treatment technology	19
Availability of the efficient plants to be used for the constructed wetlands locally	20
Availability of filter materials—substrates materials like the aggregate	21

summarizes the final scoring and ranking of the challenges of having CWs according to the Jordanian stakeholders.

3.1.2. Community Level

One hundred and nine (109) Jordanians have filled in the questionnaire and answered the categories of questions. Descriptive statistics were run against all the variables. The frequency analysis for each question has been analyzed and summarized.

For the first question category, it was found that 54.1% of the respondents were aged between 31–45 years, and 56% of the respondents were males, while 44% were females. Most of the respondents have a bachelor’s degree, with a percentage of 73.4%. The geographical distribution of the respondents is described in Figure 1. It was found that 47% of the responses came from Amman, the capital of Jordan, the second largest percentage with 29% of the responses came from Irbid, and the remaining responses were recorded from other cities in Jordan.

The second category of the questions consisted of general awareness questions about the water sector in Jordan and the climate change impacts on the country. It was found that most Jordanian respondents are aware about climate change. A total of 98% of the respondents thought climate change affected Jordan, 78.9% of the respondents believed that climate change has a fast impact on Jordan, while 21.1% believed it has a slow impact. A total of 89% of the respondents thought and agreed that Jordan is facing water scarcity.

The next category was targeting the respondent’s sanitation situation and their knowledge about the sanitation services. It was found that 78.9% of the respondents are served with a sewer network, while 21.1% are not, and this 21.1% have onsite solutions like septic tanks (sealed and unsealed). Only 31.2% of the respondents knew the wastewater treatment plant to which they are connected; this low percentage reflects the lack of knowledge and lack of interest in the sanitation sector. It was found that 40.4% of the respondents manage their wastewater costs every three months with the water bills, while 15.6% manage their costs monthly through desludging services, and 11% do not pay any costs to manage their wastewater. The remaining percentage did not know how they manage this service. For the actual costs, it was found that 24.8% of the respondents pay between 1 to 5 JD per month to dispose of their wastewater, while 11% pay between 5 to 10 JD, another 11% pay from 10 to 20 JD, and few people pay more than 40 JD monthly.

The next category measured people’s acceptance of having wastewater treatment plants, and their awareness about NbS. It was found that 82.6% of the respondents did not agree with having a wastewater treatment plant close to their living area, and only 26.6% of the respondents were aware about NbS before filling in this survey. Only 10% mentioned that NbS is already applied in Jordan and only 18.3% knew advantages of NbS and CWs over mechanical technology before filling in the survey. However, 67.9% of the respondents were aware that the current mechanical treatment technologies are contributing to the climate change issue.

The fourth category of questions targeted the acceptance of the reuse of treated wastewater. It was found that 67% of the respondents accepted irrigating their own crops with treated wastewater, while the remaining rejected that. A total of 36.7% of the respondents have accepted to reuse treated wastewater for crop irrigations in Jordan, while 19.5% do not accept that, and 5.5% strongly did not accept that. It was also found that 60% of the respondents accepted consuming products irrigated with treated wastewater while 40% rejected that.

The next question was created to understand the community’s preferences during the implementation of CWs as a wastewater treatment plant (WWTP) in their town. The Jordanian community prioritized and ranked eleven benefits according to their opinions.

Table 3. Summary of the community’s preferences of benefits of having CWs/WWTP.

Benefits	Rank
Protecting human health from diseases and illness	1
System that provides source of water (reusing treated wastewater)	2
Less gas emissions and carbon sequestration, constructed wetlands can absorb CO2, a step to face the climate change	3
Biodiversity restoration and attracting wildlife	4
Source of the harvested reeds/plants can be used in the local market with economic value	5
Very limited energy required (almost zero) during operation	6
Green area that can be an aesthetic place people can enjoy	7
Easy system to operate and maintain and does not require skilled labor	8
System with very low costs in operation and maintenance	9
Protecting the environment from the discharging untreated wastewater	10
Creating job opportunities for people in the operation of the treatment wetland	11

shows the ranked benefits with the percentage of ranking.

It was found that the community ranked “protecting human health” as the first priority of having CWs, followed by “the system provides source of water”. As a third option, they voted for “less gas emissions and absorbing CO₂”. These three options reflect the level of awareness in the Jordanian community with the issues of waster scarcity, climate change issues, and the importance of having adaptation measures.

The next category of questions focused on the concerns and issues that might arise when selecting and operating CWs. In summary, 63.3% of the respondents were afraid of odor problems, 84.4% were concerned about attracting insects and mosquitoes, and 81.7% believed that CWs required a large land area. However, 70% of the respondents did not have a problem with restoring biodiversity in their towns. These concerns are quite normal compared to their knowledge and experiences with the already existing technologies of treating wastewater.

The following questions directly approached the willingness to accept having CWs as a treatment technology. It was found that 82.6% preferred CWs over mechanical solutions, and 78.9% accepted having CWs in their town or cities. However, 67% of the respondents rejected having CWs close to their household. This can be justified from the current reputation of wastewater treatment plants, also due to the lack of treatment plants using CWs in the country.

The next category targeted the evaluation of the future prospective of the reuse of harvesting reeds from CWs within the local market in order to integrate the circularity concept with CWs. A total of 61% of the respondents thought the harvested reeds can be used locally. Different reuse options have been selected, validated, and summarized in

Table 4. Summary of reuse options for harvested reeds.

Reuse Options	Frequency	Rank	Percentage (%)
Decoration and sunshades	75	1	27.27
Feeding animals	65	2	23.64
Composting and fertilizer	60	3	21.82
Burning and heating in winter	57	4	20.73
I do not know	10	5	3.64
Nothing mentioned above	2	6	0.73
Production of Biofuel (Cellulosic Ethanol)	2	6	0.73
For the drinks and food industry	1	8	0.36
Furniture	1	8	0.36
It can be used for isolation in building construction	1	8	0.36
Air purification and an aesthetic view	1	8	0.36
Total	275		100.00

.

The next question category measured people’s willingness to pay for having CWs and enjoying the benefits and the co-benefits of having CWs. It was found that 78.9% of the respondents are WTA using CWs as a treatment system in their town, and it was also found that 53.2% of the respondents were willing to support and pay for implementing CWs in their towns and cities, 27.5% accepted to pay on a monthly basis, and 32.1% accepted to pay one time only. A total of 11.9% were willing to pay but they did not know how much needed to be paid, while 28.4% rejected to pay. It can be summarized that only 28.4% rejected to pay, while 71.6% were willing to pay for having CWs and enjoying the benefits and co-benefits. Only 33% of the respondents accepted having CWs as a treatment system near their households, reflecting the general negative perception of treatment systems. The last category approached another application of CWs, which is to treat greywater at the household level; these questions were measuring people’s WTA and WTP for having CWs at their household. It was found that 80.7% of the respondents accepted having CWs in their household if the CWs will provide them with a source of water for toilet flushing or irrigation. A total of 56.9% of the Jordanians accepted to pay for having CWs. The number shows that 34.9% accepted to pay up to 100 JD to have CWs, 2.8% accepted to pay up to 500 JD, and 1% accepted to pay more than 1000 JD to have it, while 42.2% accepted having CWs but without paying.

Generally, the overall results showed that people’s WTA of CWs to treat greywater is 80.7%. Meanwhile, people’s WTA of CW as a treatment system to treat wastewater near their household is 33% only, as illustrated in Figure 2 and Figure 3 below.

3.2. Contingent Valuation (CV) Method

In order to calculate the mean WTP to have CWs at the household level to treat greywater, the following methodology and calculation were followed:

• Collection of responses: the frequency of respondents who answered “yes” to the willingness to pay (WTP) question for having CWs at the household level to treat greywater was collected for various proposed financial bids;
• Ranking of financial bids: the financial bids were ranked from one to six based on their values, with one representing zero payment (do not pay) and six representing the highest proposed bid value (2000 JD);
• Calculation of WTP per bid group: for each bid group, the WTP was calculated by multiplying the frequency of respondents who answered “yes” by the ranking value for that specific bid;
• Calculation of mean WTP: the mean WTP was calculated by dividing the total WTP per group by the total number of respondents;
• Translate the mean WTP value into the BID level through the ranked value into “Value” column in

  Table 5. Values of WTP and collected answers.

  BID Level (JD)	No. Sub Sample	No. of Sample Answering Yes	% Answering Yes for Each Group	Value	WTP per Group
  0	46	5	11%	1	5
  0–100	38	34	89%	2	68
  100–200	17	17	100%	3	51
  200–500	3	2	67%	4	8
  500–1000	4	3	75%	5	15
  >1000	1	1	100%	6	6
  Total	109				153

  Note(s): Mean WTP = ${\displaystyle \frac{\mathrm{t}\mathrm{o}\mathrm{t}\mathrm{a}\mathrm{l} \mathrm{W}\mathrm{T}\mathrm{P}}{\mathrm{N}\mathrm{o} \mathrm{o}\mathrm{f} \mathrm{s}\mathrm{a}\mathrm{m}\mathrm{p}\mathrm{l}\mathrm{e}\mathrm{s}}}$ = ${\displaystyle \frac{153}{109}}$ = 1.4 → (0 − 100) JD/person.

  .

3.3. Regression Analysis

To understand the parameters that affect people’s WTP and WTA for having CWs-NbS, a regression model was used. Questions related to the WTP and WTA were considered as dependent variables and other questions were considered as independent variables. Since the questions were categorized in groups as mentioned before, several regressions were carried out to study the correlations between each category and the dependent variables.

Table A1. Summary of regression analysis. Dependent variable: would you accept to have WWTP using constructed wetlands technology close to your house?

Dependent	Independent Variables	Significant/ Not Significant
Would you accept to have WWTP using constructed wetlands technology close to your house?	Age Gender Education level City	Not significant
	Are you aware about the global climate change issue? Do you think Jordan is affected by climate change impacts? Do you think climate change has a fast impact in Jordan? Do you think that Jordan is facing water scarcity issues?	A Significant
	Is your house connected to a sewer system? If your house is not connected to the sewer system, do you have a sanitation system in your household (septic tank, cesspit …)? How much does it cost you to manage your wastewater (monthly or every three months, please indicate the period)?	Not significant
	Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature-Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NbS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally?	Not significant
	Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town?	B Significant

Note(s): ^A Multiple linear regression was used to test if climate change awareness, knowledge about climate change on Jordan, whether the climate change has a fast impact on Jordan, and the knowledge about Jordanian water scarcity significantly affect the willingness to accept having CWs close to the household (“Would you accept to have WWTP using constructed wetlands technology close to your house?”). The fitted regression model was the WTA having CWs near household = 1.389 − 0.212 (climate change awareness) + 0.123 (Jordan affected by climate change) + 0.371 (climate change has fast impact on Jordan) − 0.60 (Jordan water scarcity). The overall regression was statistically significant R² = 0.114, F (4, 104) = 3.361, p = < 0.012). ^B The multiple linear regression showed that the questions: Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town? significantly affect the willingness to accept having CWs close to the household (“Would you accept to have WWTP using constructed wetlands technology close to your house?”). The fitted regression model was the WTA CWs near the household = 2.599 − 0.235 (odor concerns) 0.249 (insects concerns) − 0.224 (land area concern) − 0.032 (restoring biodiversity). The overall regression was statistically significant (R² = 0.194, F (4, 104) = 6.244, p = < 0.001).

,

Table A2. Summary of regression analysis. Dependent variable: would you accept to have WWTP using constructed wetlands technology in your town/city?

Dependent	Independent Variables	Significant/Not Significant
Would you accept to have WWTP using constructed wetlands technology in your town/city?	Age Gender Education level City	Not significant
	Are you aware about the global climate change issue? Do you think Jordan is affected by climate change impacts? Do you think climate change has a fast impact in Jordan? Do you think that Jordan is facing water scarcity issues?	Not significant
	Is your house connected to a sewer system? If your house is not connected to the sewer system, do you have a sanitation system in your household (septic tank, cesspit …)? How much does it cost you to manage your wastewater (monthly or every three months, please indicate the period)?	Not significant
	Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature-Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NbS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally?	C Significant
	Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town?	Not significant

Note(s): ^C The third multiple linear regression showed that the questions: Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature-Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NBS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally? significantly affect the willingness to accept having CWs in the city/town (“Would you accept to have WWTP using constructed wetlands technology in your town/city?”). The fitted regression model was the WTA CWs in their city/town = 0.241 − 0.049 (knowledge about GHGs from mechanical technology) + 0.11 (knowledge about NBS-CWs) + 0.154 (knowledge in NBS applied in Jordan) + 0.064 (knowledge about advantages of NBS over mechanical) + 0.352 (preference of CV over mechanical) + 0.017 (if harvested reeds can be used). The overall regression was statistically significant (R² = 0.146, F (4, 104) = 2.901, p =< 0.012).

,

Table A3. Summary of regression analysis. Dependent variable: if you believe that this technology has the previous positive impact, are you willing to pay tax for implementing this technology in your town?

Dependent	Independent Variables	Significant/Not Significant
If you believe that this technology has the previous positive impact, are you willing to pay tax for implementing this technology in your town?	Age Gender Education level City	Not significant
	Are you aware about the global climate change issue? Do you think Jordan is affected by climate change impacts? Do you think climate change has a fast impact in Jordan? Do you think that Jordan is facing water scarcity issues?	Not significant
	Is your house connected to a sewer system? If your house is not connected to the sewer system, do you have a sanitation system in your household (septic tank, cesspit …)? How much does it cost you to manage your wastewater (monthly or every three months, please indicate the period)?	Not significant
	Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature-Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NbS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally?	Not significant
	Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town?	Not significant

,

Table A4. Summary of regression analysis. Dependent variable: if you know that constructed wetlands can be applied in your household to treat the greywater (water coming from kitchen, sinks, and washing machines), and you can use the treated water in irrigation in your yard or for toilet flushing, would you willing to have this technology in your house?

Dependent	Independent Variables	Significant/Not Significant
If you know that constructed wetlands can be applied in your household to treat the greywater (water coming from kitchen, sinks, and washing machines), and you can use the treated water in irrigation in your yard or for toilet flushing, would you willing to have this technology in your house?	Age Gender Education level City	Not significant
	Are you aware about the global climate change issue? Do you think Jordan is affected by climate change impacts? Do you think climate change has a fast impact in Jordan? Do you think that Jordan is facing water scarcity issues?	Not significant
	Is your house connected to a sewer system? If your house is not connected to the sewer system, do you have a sanitation system in your household (septic tank, cesspit …)? How much does it cost you to manage your wastewater (monthly or every three months, please indicate the period)?	Not significant
	Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature-Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NbS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally?	Not significant
	Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town?	D Significant

Note(s): ^D For the using CWs for treatment greywater at the household level, multiple linear regression showed that the questions: Do you think this technology can be source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town? significantly affect the willingness to accept having CWs in the household to treat greywater (“If you know that Constructed wetlands can be applied in your household to treat the greywater, would you willing to have this technology in your house?”). The fitted regression model was the WTA CWs in households = 1.734 − 0.228 (odor concerns) + 0.03 (insects concerns) − 0.061 (land area concern) − 0.119 (restoring biodiversity). The overall regression was statistically significant (R² = 0.094, F (4, 104) = 2.703, p = < 0.034).

and

Table A5. Summary of regression analysis. Dependent variable: would you accept to pay for having constructed wetlands in your house?

Dependent	Independent Variables	Significant/Not Significant
Would you accept to pay for having constructed wetlands in your house?	Age Gender Education level City	Not significant
	Are you aware about the global climate change issue? Do you think Jordan is affected by climate change impacts? Do you think climate change has a fast impact in Jordan? Do you think that Jordan is facing water scarcity issues?	Not significant
	Is your house connected to a sewer system? If your house is not connected to the sewer system, do you have a sanitation system in your household (septic tank, cesspit …)? How much does it cost you to manage your wastewater (monthly or every three months, please indicate the period)?	Not significant
	Do you know that the conventional mechanical wastewater treatment plants are considered a source of GHGs which contribute to climate change? Do you know constructed wetlands—Nature Based Solution technology which can be used to treat wastewater? Do you know if it is applied in Jordan? Do you know any advantages and benefits of using constructed wetlands—NbS technology over the mechanical technology? Do you prefer having constructed wetlands over the mechanical one? Do you think the harvested reeds/plants (which will be harvested periodically) can be used locally?	Not significant
	Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town?	E Significant

Note(s): ^E For WTP for having and using CWs for the treatment of greywater at the household level, the multiple linear regression showed that the questions: Do you think this technology can be a source of odor? Do you think this technology attracts insects and mosquitos? Do you think this technology requires a large land area? Do you have a problem with attracting birds and restoring biodiversity in the town? significantly affect the willingness to pay for having CWs in the household to treat greywater (“Would you accept to pay for having Constructed wetlands in your house?”). The fitted regression model was the WTP of CWs in households = 2.143 − 0.268 (odor concerns) − 0.01 (insects concerns) − 0.154 (land area concern) − 0.089 (restoring biodiversity). The overall regression was statistically significant (R² = 0.095, F (4, 104) = 2.73, p = < 0.033).

in Appendix A summarize the regression analysis carried out and their results of significance. The regression analysis was conducted only for the community level survey as it aimed to measure the WTP and WTA of the selected community.

It is important to remember that in SPSS, the regression analysis calculates a p-value for each of the regression coefficients [22,23]. The p-value indicates if each independent variable affects the dependent variable in a significant/non-significant way. A low p-value (<0.05) indicates that an independent variable is likely to be a meaningful addition to the dependent variable (WTA and WTP). Equally, a larger p-value suggests that changes in the independents are not associated with changes in the dependent [23].

The regression analysis reveals that community acceptance (WTA) and willingness to pay (WTP) for CWs are primarily influenced by specific concerns such as a potential odor, the attraction of insects, and land use requirements. Addressing these points could significantly improve WTA and WTP levels. Design strategies, such as using proper vegetation to reduce odors and implementing measures to prevent the attraction of nuisance insects, can effectively address these concerns. Showing people practical examples that emphasize that odor is not a problem when the system is functioning effectively can help alleviate these concerns. For land use requirements, innovative ideas such as integrating CWs with green roofs and green walls can minimize the required land while providing additional environmental and aesthetic benefits. Additionally, the awareness of climate change and Jordan’s water scarcity issues play a crucial role in shaping favorable attitudes toward CWs. The respondents’ understanding of NbS, including CWs’ contributions to climate change mitigation and other benefits, also impacts WTP and WTA. Consequently, conducting awareness-raising sessions during the feasibility phase of CW projects could be instrumental in fostering community support. Although environmental awareness significantly affects attitudes, sociodemographic factors (age, gender, education level, and city) were not found to significantly impact the acceptance of NbS in wastewater management. This suggests that while broad environmental education can enhance acceptance, tailored engagement strategies addressing specific community concerns may be equally critical.

4. Conclusions

The survey results highlight the potential of CWs and NbS as sustainable sanitation systems with benefits extending beyond wastewater treatment. This study highlighted the co-benefits of CWs, referring to environmental and social co-benefits, including habitat diversity, recreational opportunities (e.g., bird watching), temperature regulation, and aesthetic enhancements for both urban and rural settings. These features position CWs as appealing, community-centered solutions. Integrating such benefits within the framework of financial sustainability can support the transition toward a circular economy, making CWs an increasingly attractive option.

This study, which included a two-level survey of stakeholders and community members, leveraged the contingent valuation (CV) method to evaluate the willingness to pay (WTP) and willingness to accept (WTA) CWs as sanitation options. The findings indicate that community members and stakeholders have distinct perceptions about CW challenges and benefits, pointing to the need for careful project planning, including raising public awareness of CW advantages. The analysis also reveals that community willingness to accept CWs varies based on the application; decentralized, household-level CWs for greywater treatment receive a higher WTA and WTP compared to larger CW systems situated near residential areas or at town or city scales. This suggests a promising role for decentralized solutions in the Jordanian context, especially at the household level, to enhance public acceptance.

The findings revealed that 78.9% of the respondents were willing to accept (WTA) CWs as a wastewater treatment system in their towns, though only 33% were WTA CWs near their households, reflecting general negative perceptions of treatment systems. Additionally, 53.2% of respondents were willing to pay (WTP) for CWs in general. For greywater treatment at the household level, 80.9% were WTA, with 56.9% WTP for installation. The higher percentages for greywater treatment are likely due to the direct benefits households would receive, such as a source of water for irrigation or other uses.

Key factors influencing WTP and WTA include concerns about odor, insects, and the land required for CWs, alongside broader environmental awareness regarding climate change and water security. General knowledge about NbS and CWs’ environmental benefits also plays a role. The regression analysis further reinforces that, while the awareness of climate change and local water scarcity significantly shape positive attitudes toward CWs, demographic factors such as age, gender, education, and location do not have substantial impacts. This indicates that environmental consciousness is a stronger driver of acceptance than sociodemographic characteristics, suggesting that targeted awareness-raising could effectively boost public support for CW projects.

For policymakers, the findings offer actionable insights to promote the adoption of NbS in Jordan. Decision-makers can use the study results to design public awareness campaigns tailored to address community concerns such as odor, insects, and land use. Policies supporting practical demonstrations of successful CW projects and their co-benefits, such as restoring biodiversity, reusing harvested reeds, and aesthetic enhancements, can foster greater trust and acceptance among the public. Furthermore, integrating innovative solutions like green roofs and walls into CW designs can address land use concerns and appeal to urban communities.

Future studies should explore the role of sociocultural norms, such as community involvement in environmental decisions and the impact of targeted public awareness campaigns, in shaping acceptance. Highlighting local success stories of CWs and their benefits can further strengthen community support. Additionally, future research should evaluate the economic benefits of wetland construction across various scenarios, enhancing the understanding of CWs’ value within different socioeconomic and environmental contexts.

Overall, these findings emphasize the importance of addressing community concerns, emphasizing environmental co-benefits, and incorporating innovative design strategies to maximize the adoption of CWs and NbS in Jordan. With the right combination of policy support, public awareness, and practical demonstrations, CWs can play a pivotal role in advancing water security and climate resilience in Jordan and beyond.