Light greywater (LGW) has significant potential for reuse at the household level compared to other domestic wastewater effluents. However, social acceptance remains a major barrier to its implementation. This study provides a novel analysis of domestic water consumption habits and public perceptions of LGW reuse within an urban residential area in Latin America. Data were collected through a household survey (n = 132) and analyzed using descriptive and inferential statistics. Seventy-four per cent of respondents were willing to adopt this water reclamation scheme. Education level significantly influenced perceptions of reuse, while gender and age had no significant effect. Personal attitudes, self-perceived capacity, and water consumption habits, particularly the frequency of handwashing, tooth brushing, and toilet flushing, were key drivers of the LGW generation and shaped public perceptions. Higher per capita water consumption associated with these activities underscores the feasibility of LGW reuse, particularly for most preferred applications like toilet flushing (81%) and floor cleaning (67%), which involve minimal human contact. Most respondents expressed willingness to invest in LGW reuse systems (73%), perform operational tasks (77%), and conduct maintenance activities (64%). The study identified five challenges hindering LGW reuse at the household level and proposed strategies to address them in the Colombian context.

  • Social acceptance of light greywater (LGW) reuse was analyzed.

  • About 74% of the study's participants are willing to reuse LGW.

  • The main reasons for refusing to reuse LGW include health risks, space requirements, and odor emissions.

  • The most accepted applications for LGW are toilet flushing and floor cleaning.

  • Technical and non-technical challenges for LGW reusing are discussed in the Colombian urban context.

Water scarcity is a growing global issue, with over two billion people living in water-stressed regions and nearly four billion experiencing physical water scarcity at least once annually (UN-Water 2020). Rapid urbanization, industrialization, and population growth exacerbate these challenges by straining water supply systems and increasing wastewater discharge, thereby reducing the availability and quality of water resources. Addressing these issues requires innovative urban water management strategies, including alternative water sources such as wastewater reuse.

Reuse of greywater (GW) at the household level is a widely studied strategy to mitigate water scarcity. It involves collecting wastewater from sources, treating it, and distributing it for domestic water use (Craig & Richman 2018; Khajvand et al. 2022). Light greywater (LGW), which consists of wastewater from bathtubs, showers, and hand basins, is considered to have a lower pollutant load than other types of GW. Therefore, it is particularly suitable for low-complexity treatment technologies (Khalil & Liu 2021; Morandi et al. 2021; Aguirre-Álvarez et al. 2024). Treated LGW can be used for water-intensive domestic activities such as watering gardens, car washing, toilet flushing, and house cleaning (Leiva et al. 2021; Angelova et al. 2024). Given that LGW accounts for approximately 48% of domestic wastewater (Shaikh & Ahammed 2020), its reuse has the potential to significantly reduce potable water consumption.

Despite the availability of suitable technologies and evidence of financial feasibility for household-level GW reuse in developing countries (Domínguez et al. 2017; Oviedo-Ocaña et al. 2018), effective implementation depends on both technical factors and public acceptance. Therefore, it is critical to understand the household water use behavior that influences LGW generation (Noutsopoulos et al. 2018) and the social perception surrounding LGW reuse systems (Radingoana et al. 2020; Roopnarine et al. 2023). Social perception reflects a community's shared opinions and beliefs, shaped by its sociocultural and economic characteristics (Portman et al. 2022). In this context, behavioral theories such as the Theory of Planned Behavior (TPB) provide valuable frameworks for analyzing public acceptance.

The TPB posits that people's behavior is influenced by attitudes (positive or negative evaluations of the behavior), subjective norms (perceived social pressure to engage in the behavior), and perceived behavioral control (perceived ability to perform the behavior) (Ajzen 1991). This framework has been widely used to analyze the public acceptance of environmental practices, including water reuse systems in developing countries (Oteng-Peprah et al. 2020). Additionally, studies have examined the influence of sociodemographic factors on social perceptions and willingness to adopt GW reuse. For instance, gender and age influenced acceptance in Palestine (Al-Khatib et al. 2022), while education was a key factor in Saudi Arabia (Mu'azu et al. 2020). In the USA, variables such as ethnicity, income, location of residence, and education level were significantly associated with the acceptance of reclaimed water programs (Garcia-Cuerva et al. 2016). Willingness also varies by intended use, with studies in low-income communities from developing countries highlighting differing levels of acceptance with uses such as toilet flushing, car washing, and laundry (Madzaramba & Zanamwe 2023). These findings demonstrate the need to contextualize perceptions within specific geographic and cultural settings.

Although the social perception of GW reuse has been studied in various contexts, most of the research has focused on developed countries, with limited studies focusing on the Global South (Fielding et al. 2019; Madzaramba & Zanamwe 2023). Moreover, studies specifically addressing the public acceptance of LGW reuse are scarce. Existing literature suggests a lack of studies analyzing people's willingness to reuse LGW and the factors influencing it in the context of Latin American developing countries. This gap hampers the adoption of water reclamation strategies designed at alleviating water issues in the region, particularly due to the unique challenges that hinder LGW reuse at the household level. These effluents are characterized by intermittent hydraulic loads and the presence of emerging pollutants and pathogens, which can influence both public perception and the implementation of reuse systems.

This study aims to address these gaps by investigating public acceptance and household water use behaviors related to LGW reuse in an urban area of Bucaramanga, northeastern Colombia. To the authors' knowledge, this is the first study to explore public perceptions of LGW reuse in Colombia, providing a foundation for understanding the social factors influencing LGW reuse in other Latin American developing countries. Specifically, this research examines: i) water consumption behaviors and their relationship with hygiene and domestic water use habits and ii) social perceptions regarding LGW reuse acceptability, reasons for rejection, potential uses, and willingness to invest in, operate, and maintain LGW systems. This analysis provides actionable insights into the technical and non-technical challenges hindering LGW reuse at the household level and offers pathways for promoting sustainable water reuse practices in urban areas from developing countries.

Study area

The study was conducted in the ‘La Victoria’ neighborhood of Bucaramanga Santander, Colombia (Figure 1). This predominantly residential area comprises 1,705 households. Typical households in La Victoria include a living room, kitchen, three to four bedrooms, one to two bathrooms, and a patio. The study area has 100% coverage of potable water supply, sewage, and solid waste management services. The selected neighborhood is classified as a middle socioeconomic area, representing the status of 61% of Bucaramanga's population (Alcaldía de Bucaramanga 2015).
Fig. 1

Location of the study area.

Fig. 1

Location of the study area.

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Characterization of domestic water use habits and public perception on LGW reuse

Questionnaire design

We designed a questionnaire to collect both quantitative and qualitative data (see Supplementary Material), encompassing three sections: (i) general information about the community, including sociodemographic variables such as gender, age, marital status, education level, and employment status; (ii) domestic water use habits, focusing on the frequency and types of activities contributing to LGW generation; and (iii) social perception on treated LGW reuse. The questionnaire's structure and content were based on prior studies on the public acceptance of water reuse and its influencing factors (Akpan et al. 2020; Msaki et al. 2022).

The final section of the survey included questions addressing attitudes toward LGW reuse and people's perceived ability to implement LGW reuse systems, aligning with two components of the TPB. Questions related to subjective norms were excluded, as this component may be less relevant in the Colombian context where LGW reuse is not yet widely practiced. Since subjective norms depend on the behaviors and opinions of others, the absence of established practices or widespread awareness of LGW reuse in the community likely limits the influence of this factor.

Pilot test and sample size determination

A preliminary survey was conducted as a pilot test with 35 respondents to assess the effectiveness and suitability of the questionnaire for the study. The sample size for the main survey was calculated using domestic per capita water consumption data obtained from the pilot test. Equation (1), proposed by García-García et al. (2013), was applied to determine the required sample size, resulting in a total of 132 households:
(1)

In Equation (1), n represents the sample size, while Z is the value associated with the selected confidence level, set at 1.96 for a 95% confidence level. The standard deviation (S) of the per capita water consumption data from the pilot test was 2.20, and the standard error of the mean (δ) for the same data was 0.37. The subsample size from the pilot test (n′) was 35, and N, representing the total number of households in the neighborhood, was 1,705.

Data collection

The survey was conducted through face-to-face interviews with the head of the households (i.e., mother or father) or another permanent resident aged 18 or older. Respondents were selected using a convenience sampling method, following a non-probabilistic approach (Etikan et al. 2016). The interviews were conducted on weekdays between 14:00 to 20:00 from January and April 2023. This time frame was selected to accommodate the availability of most household heads and permanent residents, as these hours typically coincide with the end of workdays and ensure higher participation rates.

Prior to each interview, respondents were provided with an informed consent form outlining the study's purpose and implications. To ensure that respondents, including those with no prior knowledge of LGW reuse, could effectively engage with the questionnaire, surveyors provided a brief introduction to LGW fundamentals and potential technologies for its treatment and reuse. This introduction, delivered in simple language, aimed to standardize participants' baseline understanding and minimize bias arising from varying levels of prior knowledge. However, we recognize that respondents with existing knowledge of LGW reuse may have had preconceived opinions, potentially influencing their responses.

Further, it is relevant to point out that the use of a non-probabilistic convenience sampling method introduced inherent limitations in this study, including the potential for selection bias and restricted generalizability of the findings to other communities. Convenience sampling, while practical for exploratory research, may not fully represent the target population's diversity. Future studies should consider employing probabilistic sampling methods to enhance representativeness and reduce biases. Additionally, while the selected survey hours aimed to maximize participation, they may have inadvertently excluded residents with non-standard working hours or other obligations, potentially skewing the demographic composition of the sample.

Data analysis

Survey data were tabulated and analyzed using Microsoft Excel® and R (R Core Team 2023), with a significant level of 0.05 applied to all the statistical tests. Descriptive statistics were used to summarize sociodemographic variables, domestic water use habits, per capita water consumption, and variables related to social perception of LGW reuse. The Anderson-Darling test and the Levene test were used to examine the normality of data distribution and the homogeneity of variances, respectively (see Table S1 in Supplementary Material). To evaluate the impact of specific factors on domestic per capita water consumption, we applied the Kruskal–Wallis test to examine whether household size (i.e., number of family members), the frequencies of handwashing, showers, and hand basin cleaning, and toilet flushing were significant determinants. The Dunn post hoc test was used to identify significant differences among households with varying levels of those factors. Additionally, the Wilcoxon rank-sum test was applied to evaluate the influence of brushing and showering frequencies on per capita water consumption. Pearson's Chi-square test was utilized to examine the relationship between sociodemographic variables and people's willingness to reuse LGW. Moreover, Fisher's exact test was used to study the relationships between sociodemographic variables and the public perception regarding the risks of reusing LGW, the potential investment that individuals may afford for implementing a LGW reuse system, and the preferred frequency for operating and maintaining such systems.

Identification of challenges facing LGW reuse at the household level for the study context

To identify and describe the technical and non-technical challenges hindering the adoption of LGW reuse at the household level in our study context, we analyzed the results of this research alongside the relevant policy, regulatory, and institutional frameworks. Additionally, we integrated key findings from previous studies. This comprehensive approach provided a holistic understanding of the barriers to LGW reuse adoption in developing countries like Colombia.

Domestic water use habits and perception of LGW reuse

Sociodemographic characteristics

Figure 2 illustrates the sociodemographic characteristics of the respondents. Women comprised 72% of the respondents. Most households consisted of three to four family members (56%). The education level was relatively high, with 70% of respondents holding either a technical or professional degree. Most of the interviewees (61%) were married, and 60% were 40 years old or older.
Fig. 2

Sociodemographic characteristics of the interviewed persons.

Fig. 2

Sociodemographic characteristics of the interviewed persons.

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Factors affecting domestic water consumption

Per capita water consumption in the residential study area was 166.25 ± 47.17 L per−1 day−1, exceeding the Colombian technical regulation for this population (130 L per−1 day−1) (Ministerio de Vivienda, Ciudad y Territorio 2017). Figure 3 presents per capita water consumption by home size (i.e., number of residents per household). More than half (55%) of the surveyed households consisted of three to four family members, while only 4% of the households had more than five members. Home size significantly influenced per capita water consumption (p-value < 0.05), with the post hoc Dunn test revealing that households with one member consumed significantly more water per capita than those with two members (Figure 3).
Fig. 3

Boxplots for per capita water consumption categorized by family size. Note: the ‘x’ symbol inside the boxes represents mean values of the datasets; n: number of surveyed households; means with at least one common letter are not significantly different by the Dunn test at the 5% level of significance.

Fig. 3

Boxplots for per capita water consumption categorized by family size. Note: the ‘x’ symbol inside the boxes represents mean values of the datasets; n: number of surveyed households; means with at least one common letter are not significantly different by the Dunn test at the 5% level of significance.

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Home size is one of the most examined determinants of water consumption, with varying results (Cominola et al. 2023). While some studies in developing countries report a strong negative correlation between home size and per capita water consumption (Alharsha et al. 2022; da Veiga et al. 2023), others, such as Arbués et al. (2010) in Zaragoza, Spain, found no direct relationship. These authors suggest that economies of scale in water use, particularly for cleaning tasks, may explain the lack of correlation. Nevertheless, domestic water consumption habits (e.g., washing machine full loads and shorter showers) also play a critical role in water conservation and may influence per capita water consumption (Jorgensen et al. 2009).

In our study, specific domestic activities significantly influenced per capita water consumption (Table 1). We observed an increase from 150.1 L per−1 day−1 for households washing hands fewer than five times daily to 203.2 L per−1 day−1 for those washing hands up to 20 times daily. The increase in the frequency of handwashing could be associated with hygiene practices adopted during the COVID-19 pandemic to curb the spread of the virus (Olupot et al. 2021). Respondents who brushed their teeth more than three times daily consumed 19% more water per capita than those who brushed fewer times. Households, where members showered twice daily (57% of respondents), had 13% higher per capita water consumption than those showering once daily. Water consumption decreased as the frequency of cleaning declined, from 179 L per−1 day−1 for daily cleaning to 141 L per−1 day−1 for monthly cleaning. However, no significant effect on the per capita water consumption was observed for this activity.

Table 1

Domestic activities influencing water consumption and LGW generation and their frequency in the surveyed households.

ActivityFrequencynWater consumption*
[L per−1 day−1]
Daily handwashing ≤5 times 46 150.11 ± 41.62c 
5–10 times 42 161.53 ± 34.99bc 
10–15 times 22 187.15 ± 47.72ab 
15–20 times 190.12 ± 42.40abc 
≥20 times 13 203.21 ± 58.04a 
Daily tooth brushing ≤3 times 99 160.34 ± 42.63b 
>3 times 33 190.47 ± 48.50a 
Showering Once daily 56 155.81 ± 34.95b 
Twice daily 76 176.76 ± 45.73a 
Cleaning of showers and hand basins Daily 11 179.80 ± 90.46 
Three times per week 174.81 ± 33.93 
Two times per week 37 167.91 ± 42.15 
Weekly 62 168.02 ± 38.63 
Biweekly 11 154.04 ± 49.20 
Monthly 141.67 ± 11.79 
Toilet flushing ≤5 times 80 149.01 ± 36.80c 
5–10 times 33 182.81 ± 41.56b 
≥10 times 19 221.35 ± 36.08a 
ActivityFrequencynWater consumption*
[L per−1 day−1]
Daily handwashing ≤5 times 46 150.11 ± 41.62c 
5–10 times 42 161.53 ± 34.99bc 
10–15 times 22 187.15 ± 47.72ab 
15–20 times 190.12 ± 42.40abc 
≥20 times 13 203.21 ± 58.04a 
Daily tooth brushing ≤3 times 99 160.34 ± 42.63b 
>3 times 33 190.47 ± 48.50a 
Showering Once daily 56 155.81 ± 34.95b 
Twice daily 76 176.76 ± 45.73a 
Cleaning of showers and hand basins Daily 11 179.80 ± 90.46 
Three times per week 174.81 ± 33.93 
Two times per week 37 167.91 ± 42.15 
Weekly 62 168.02 ± 38.63 
Biweekly 11 154.04 ± 49.20 
Monthly 141.67 ± 11.79 
Toilet flushing ≤5 times 80 149.01 ± 36.80c 
5–10 times 33 182.81 ± 41.56b 
≥10 times 19 221.35 ± 36.08a 

*Values represent the mean ± standard deviation of daily water consumption for all household activities.

n: number of respondents; means with at least one common letter are not significantly different at the 5% level of significance.

Toilet flushing frequency also showed a significant impact on water consumption, with a 49% increase observed between households flushing fewer than five times daily and those flushing 10 or more times daily. As Mazzoni et al. (2023) highlighted, showering and toilet flushing are the largest contributors to domestic water use, averaging 44.1 and 38.0 L per−1 day−1, respectively. Given the high water demand and low water quality requirements for toilet flushing, it represents a promising application for treated LGW. Additionally, the proportions of LGW in domestic wastewater (50% in high-income countries and 48% in low-income countries) (Shaikh & Ahammed 2020) underscore the potential water savings achievable through LGW reuse systems. Our findings highlight the need for further studies to accurately estimate LGW flows, facilitating the technical design of reuse systems tailored to urban households.

Factors affecting the acceptability of LGW reuse

We found that 74% of respondents are willing to reuse LGW at the housing level. Figure 4 illustrates the proportion of respondents willing to reuse treated LGW by gender, age group, and education level, while Table 2 summarizes the statistical analysis of these relationships. As shown in Figure 4, both men and women exhibited high acceptance levels (>70%) for using treated LGW, and no significant relationship was observed between gender and willingness to adopt the LGW reuse system (Table 2). Previous studies on social perceptions of water reuse across developed and developing contexts have often found gender to be a significant determinant. Men are generally more receptive to recycled water than women, likely due to a higher acceptance of risky technologies (Fielding et al. 2019). For example, in a Latin American urban context, men showed greater willingness than women to reuse treated greywater for domestic activities (Amaris et al. 2020). Moreover, women have demonstrated reluctance toward reusing treated wastewater for activities such as cleaning and cooking, likely influenced by sociocultural norms and gender roles (Fielding & Roiko 2014; Mu'azu et al. 2020).
Table 2

Statistical relationships between sociodemographic variables and perceptions of LGW reuse.

VariableAcceptanceRisk perceptionInitial investmentOperation frequencyMaintenance frequency
Gender 0.835 0.181 0.506 0.932 0.700 
Education level 0.048* 0.005** 0.032* 0.058 0.300 
Age 0.384 0.148 0.268 0.262 0.010* 
VariableAcceptanceRisk perceptionInitial investmentOperation frequencyMaintenance frequency
Gender 0.835 0.181 0.506 0.932 0.700 
Education level 0.048* 0.005** 0.032* 0.058 0.300 
Age 0.384 0.148 0.268 0.262 0.010* 

Note: Values indicate p-values.

Significant relationships are indicated as follows: *p < 0.05, **p < 0.01.

Fig. 4

Willingness to reuse treated LGW, categorized by gender, age group, and education level.

Fig. 4

Willingness to reuse treated LGW, categorized by gender, age group, and education level.

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The absence of a significant gender influence on social perception about LGW reuse in our study area allows for generalized approaches to promotion and policy but highlights the need to focus on other determinants in this particular context. However, it is relevant to point out that gender roles could still affect the practical adoption of LGW reuse systems. For instance, in many urban areas of Latin American developing countries, including Bucaramanga, women are often the primary users and maintainers of water systems in households, which might impact the implementation stage. Exploring gender roles in operational aspects of LGW reuse could reveal practical barriers that are not immediately apparent from perception studies.

Although no significant relationship between age and LGW reuse acceptability was observed, respondents aged 20–59 years exhibited a higher willingness to adopt LGW reuse (>70%) than those aged 60 and older. While elderly respondents also expressed interest, their acceptance levels were slightly lower. This trend aligns with findings from other studies, where younger individuals in urban communities from developing countries demonstrated more favorable attitudes toward wastewater reuse (Akpan et al. 2020). This behavior could be attributed to generational divergences in perspectives on environmental sustainability and a greater receptivity of the youth toward innovative approaches (Buyukkamaci & Alkan 2013; Msaki et al. 2022).

Education level had a significant impact on LGW reuse acceptability (p < 0.01), with acceptance increasing alongside higher education levels. This finding aligns with previous studies in both developed and developing countries (Garcia-Cuerva et al. 2016; Bachi et al. 2023). Higher education likely enhances the understanding of GW treatment processes, alleviating health concerns associated with wastewater reuse (Gu et al. 2015; Al-Khatib et al. 2022). Furthermore, individuals with higher education levels may exhibit greater awareness of water scarcity and the importance of integrated water resource management, fostering positive perceptions of LGW reuse. Addressing disparities in education-related beliefs through targeted outreach could significantly increase the community acceptance of reuse systems.

Beyond sociodemographic factors, our study revealed that social perceptions of LGW reuse are also influenced by attitudes toward reusing treated LGW and individuals' self-perceived ability to implement these systems. These components, central to the TPB, become evident when examining the reasons for rejecting LGW reuse, preferred applications, and the willingness to invest in, operate, and maintain these systems. The following discussion explores these aspects as they are critical for analyzing implications for implementing LGW reuse systems in an urban residential context in Colombia.

Figure 5 highlights the primary reasons for rejecting LGW reuse, with 94% of respondents citing health risks as their main concern. These concerns emphasize the need for systems that minimize human contact with treated water, require minimal operations and maintenance, and are designed for non-contact applications (Dolnicar et al. 2011; Portman et al. 2022). The space required for implementing a LGW reuse system at the household level was also an important reason for its rejection in the studied neighborhood. Figure 6 shows that 55% of the interviewees who refuse to reuse LGW live in houses with areas less than 150 m2. In contrast, people living in households with areas of 200 m² or more did not report space as a concern, though such households represent a small portion of the study area.
Fig. 5

Respondents' reasons for rejecting LGW reuse; number of respondents (n) = 34.

Fig. 5

Respondents' reasons for rejecting LGW reuse; number of respondents (n) = 34.

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Fig. 6

Respondents' perception on LGW reuse, categorized by household area; n: number of respondents.

Fig. 6

Respondents' perception on LGW reuse, categorized by household area; n: number of respondents.

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Moreover, odor emission was the third most relevant reason for rejecting LGW reuse. We did not find a significant relationship between this reason and the sociodemographic variables considered (i.e., gender, age, and education level). While reusing LGW has many advantages for water management, the barriers to its implementation include odor emission and insect infestation, which may be linked to the lack of training of beneficiaries leading to inadequate operation and maintenance of such systems (Thaher et al. 2020). This barrier is potentially linked to poor GW storage practices that can cause septic conditions within 1–2 days, deteriorating water quality and generating odor (Al-Khatib et al. 2022).

Figure 7 indicates the preferred applications for LGW reuse, with over 80% of respondents supporting its use for toilet flushing and floor cleaning. Conversely, fewer than 10% were willing to reuse treated LGW for handwashing or laundry. This finding is consistent with studies in the Global South that highlight public hesitation toward reusing applications involving direct human contact (Madzaramba & Zanamwe 2023). This reluctance reflects heightened health concerns, which reduce the acceptance of high-contact applications. Prior research has also shown greater acceptance for non-contact applications such as toilet flushing, car washing, and garden irrigation (Jamrah et al. 2008; Abdelrahman et al. 2020; Akpan et al. 2020). In Colombia, similar trends have been observed, with treated GW reuse widely accepted for toilet flushing, garden irrigation, and floor cleaning (Domínguez et al. 2017; Oviedo-Ocaña et al. 2018).
Fig. 7

Tendencies toward options for LGW reuse; number of respondents (n) = 98.

Fig. 7

Tendencies toward options for LGW reuse; number of respondents (n) = 98.

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Reusing LGW for toilet flushing and irrigation can reduce urban water consumption by 30–50% (Mahmoudi et al. 2021). For example, implementing GW reuse for toilet flushing in the UK could save approximately 31 m³ of water per household annually (Memon et al. 2005). In Malaysia, using GW for irrigation and toilet flushing has achieved a 50% reduction in water consumption (Mohamed et al. 2016). These findings underscore the potential environmental benefits of LGW reuse in addressing urban water challenges.

Figure 8 indicates that 64% of respondents were willing to invest less than $700 to implement a household-level LGW reuse system. Education significantly influenced willingness to invest (p < 0.05), with individuals with higher education levels more likely to afford such systems. Financial constraints remain a critical barrier, particularly in Colombian households where plumbing systems do not separate GW from blackwater. The installation or modification of pipelines for GW separation involves additional costs (Oh et al. 2018). In addition, energy consumption is a relevant factor that impacts operation costs, although GW reuse systems with low energy consumption are more financially feasible than those with high energy consumption requirements (Memon et al. 2005). Incentives such as subsidies or rebates from governments and regulatory institutions could address these barriers and encourage adoption (Garcia-Cuerva et al. 2016). On the other hand, most respondents (77%) preferred daily or weekly activities for operating LGW reuse systems (Figure S1), while maintenance activities exhibited greater variability (Figure S2), with 34% favoring monthly maintenance. These findings highlight the importance of selecting technologies that align with user preferences to ensure proper operation and maintenance.
Fig. 8

Initial investment that interviewed people are willing to afford for implementing a LGW reuse system; the number of respondents (n) = 98.

Fig. 8

Initial investment that interviewed people are willing to afford for implementing a LGW reuse system; the number of respondents (n) = 98.

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Challenges facing LGW reuse within an urban context in Colombia

This study reveals a high acceptance of LGW reuse at the household level, particularly among individuals with higher educational levels. However, key reasons for rejection include perceived health risks from direct contact with treated LGW, space requirements for system installation, and potential odor generation. Education and awareness campaigns tailored to different population sectors (e.g., by educational level) could help reduce these negative perceptions. Our findings also highlight toilet flushing as the preferred end use, as it minimizes direct contact with treated wastewater. Additionally, there is a significant willingness to participate in system operation and maintenance (daily or weekly) and to invest financially in LGW reuse systems, although incentives may be required to support these efforts. By combining these insights on social perception with an analysis of political, regulatory, institutional, and technical factors, five key challenges and strategies for addressing them in the urban Colombian context were identified and are described below.

Development of regulations for implementing LGW reuse at the household level

The promotion of wastewater reuse poses potential risks to human health, prompting global regulations to establish criteria aimed at minimizing these risks. However, most existing regulations do not differentiate between wastewater sources, focusing instead on the water quality required for various uses, and often lack updates to address current water scarcity scenarios (Voulvoulis 2018). Additionally, the limited number of water quality parameters considered in these regulations and inconsistencies in categorizing quality standards across nations and organizations hinder effective comparisons and harmonization of policies (Van de Walle et al. 2023).

In many countries, the practical implementation of GW reuse systems is further complicated by the absence of a legal framework specific to this type of wastewater (Van de Walle et al. 2023). While developed countries such as Australia, Portugal, Hong Kong, and Singapore have established regulations for general GW reuse, Latin American countries largely lack legal norms that even define ‘greywater’ (Rodríguez et al. 2022). Chile stands out as the only country in the region to have approved specific guidelines for GW reuse (Ministerio de Obras Públicas 2018).

Moreover, to our knowledge, there are no specific regulations for LGW reuse systems, either globally or regionally. Establishing such regulations is essential to position LGW reuse as a viable management strategy. These regulations should address several key dimensions of LGW recycling, including (i) specifications for the design, construction, operation, and maintenance of the systems, including pipelines to separate LGW from other domestic wastewater; (ii) minimum training requirements for personnel responsible for operation and maintenance of the systems; and (iii) quality standards for treated LGW, encompassing limits for physicochemical and biological parameters to ensure safe reuse for non-potable water applications. Beyond minimizing health risks, the introduction of specific regulations for LGW reuse could positively influence public acceptance. According to the subjective norms construct of the TPB, well-defined legal frameworks can create a sense of societal approval, encouraging individuals to adopt behaviors aligned with LGW reuse. In Colombia, addressing the absence of these regulations represents a crucial step toward promoting the widespread adoption of this sustainable water reuse practice.

Incorporation of aspects related to onsite LGW reuse systems in the study plans of various education levels

The design, construction, operation, and maintenance of alternative water supply systems and onsite wastewater reuse systems, such as those considered here for LGW reuse at the household level, require technicians, professionals, and regulatory officials to be trained in this topic. However, the lack of widespread education and training about the design and management of these systems is a challenge that hinders their application in both developed and developing countries (Rupiper & Loge 2019; Muzioreva et al. 2022).

While the benefits of LGW reuse have been increasingly recognized and acknowledged, it is necessary to develop a portfolio of educational resources for different target audiences that allow the translation of this advocacy to the achievement of meaningful impacts (Siegrist 2017). This shift will require transforming traditional engineering curricula, which focus primarily on centralized wastewater and water supply systems, to incorporate new perspectives on wastewater reuse and water reclamation (Castellanos et al. 2020; Sigahi & Sznelwar 2023). Furthermore, given our study's findings on the positive impact of education level on social acceptance of onsite LGW reuse systems, it is critical to integrate this topic not only into higher education but also into primary and secondary school curricula. Using innovative and engaging approaches to educate younger generations about the importance of decentralized water management systems could foster greater awareness and acceptance (Nourredine et al. 2023).

Development of financial incentives for encouraging LGW reuse

While various onsite GW reuse schemes have been proposed, their implementation in developing countries remains limited, primarily due to the high costs associated with modifying plumbing systems to separate GW from blackwater and sewage (Leigh & Lee 2019). To address this challenge, municipal authorities and public service providers need to develop incentives to encourage households to adopt onsite LGW reuse systems. Potential measures include: i) subsidies based on the volume of LGW reused; ii) low-interest credit schemes to finance installation costs; and iii) property tax reductions for households implementing LGW reuse systems (Chen et al. 2024).

For example, Leiva et al. (2021) found that greywater reuse systems in rural Chilean schools had not recovered their investment costs even after 20 years of financial evaluation. The study concluded that state subsidies are necessary not only to offset initial investments but also to reduce operation and maintenance costs for users. Similarly, Rodríguez et al. (2020) identified that pilot greywater reuse projects in rural Chile were financially unviable without subsidies, as the savings from reduced water consumption could not offset the investment, operation, and maintenance costs. They emphasized that regulations alone are insufficient to promote the use of these systems and proposed state-supported subsidies for initial investments. Additionally, the authors noted that water scarcity scenarios in some contexts promote the use of decentralized greywater systems, but that their evaluation must consider social and environmental variables.

Further studies are needed to evaluate the financial feasibility of LGW reuse systems, including determining payback periods and quantifying their environmental impacts. In the context of Bucaramanga, financial analyses of decentralized GW and rainwater systems for high- and low-water consumption households revealed payback periods of 22 and 26 years, respectively, when no financial support was provided (Domínguez et al. 2017; Oviedo-Ocaña et al. 2018).

Technological development adapted to households' areas and conditions

This study identified limited household space as one of the main barriers to LGW reuse at the household level. Water reuse systems often include technological components, such as storage tanks, that require significant space, hindering their adoption by communities (Campisano & Modica 2010). Similarly, a study in South Africa found that space limitations significantly impeded the adoption of water reuse systems (Moghayedi 2024). To address this challenge, the design of water reuse systems must prioritize compact and versatile technologies that minimize space requirements. For example, a study in Malaysia demonstrated the effectiveness of a compact reactor integrating three treatment steps, which improved GW quality while reducing operational costs, space needs, and equipment requirements (Ong et al. 2019). Another study in Jordan proposed a compact vertical flow constructed wetland system for GW treatment, achieving high pollutant removal efficiencies (Abunaser & Abdelhay 2020). These experiences demonstrate the feasibility of developing space-efficient technologies, which could help overcome this barrier and promote the wider adoption of LGW reuse systems in Colombian urban areas.

In addition to addressing space constraints, technological solutions must meet water quality standards for intended uses while aligning with household conditions and user preferences. Odor emission, for example, is a critical factor influencing user perception (Van de Walle et al. 2023), as identified in this study, where it emerged as a key reason for rejecting LGW reuse systems. Technologies, such as membrane bioreactors and rotating biological contactors, are widely employed for GW treatment due to their ability to produce high-quality effluents and their compact design (Atanasova et al. 2017; Abdelkader 2021). However, selecting the most appropriate LGW treatment solution for a specific context requires careful evaluation of available technologies, considering user habits and willingness to operate and maintain the systems. This approach minimizes the risks associated with contact with untreated or inadequately treated LGW. Furthermore, since most commercial greywater technologies are designed for developed markets, adapting these systems to meet the specific needs of developing regions is essential for ensuring their practicality and widespread adoption (Soong et al. 2021).

On the other hand, advancing technological development for LGW reuse requires reliable data on LGW generation, including both quantity and quality. While the scientific literature provides extensive data on general GW generation (De Gisi et al. 2015; Bakare et al. 2017; Shaikh et al. 2019; Vuppaladadiyam et al. 2019; Shaikh & Ahammed 2022), studies specifically addressing LGW characteristics remain limited (Ziemba et al. 2018; Shaikh & Ahammed 2020). Moreover, LGW generation is influenced by sociodemographic variables and domestic water use habits, which vary significantly across regions. In Bucaramanga and similar developing urban areas, systematic studies accurately estimate LGW quantity and quality, enabling the design and selection of the most reuse options tailored to local conditions and resource constraints.

Promoting LGW reuse systems for enhanced social acceptance

Public acceptance is critical for the successful implementation of greywater reuse projects (Radingoana et al. 2020). Common reasons for reluctance among residents with access to potable water include perceived health risks and the ‘yuck factor,’ an emotional reaction of disgust toward reusing treated wastewater (Portman et al. 2022). Consistent with these findings, this study identified health risks as the primary cause of rejection. Mankad (2012) describes this perception as an emotional risk, which significantly influences acceptance. The author suggests that water reuse initiatives should not focus solely on addressing emotional barriers such as fear and anxiety but should also promote positive emotions like pride and satisfaction in conserving water to facilitate adoption.

Diverse communication and dialogue strategies are necessary to educate the public about the safety and benefits of water reuse. The framing of messages, whether positively or negatively, plays a crucial role in shaping community perceptions. Messages that appeal to future-oriented emotions, reduce perceptions of risks and threats, and provide information about decentralized systems can enhance public acceptance (Mankad 2012). Additionally, while gender influence was not a significant determinant of social perception in our study, varying findings in the literature suggest that this result may not be generalizable to all urban contexts in Colombia. Therefore, communication strategies should incorporate gender-specific considerations to ensure inclusivity and maximize the effectiveness of outreach efforts. This approach is essential for addressing the prevailing societal risk perception associated with water reuse.

An example of an effective communication strategy is the one proposed by Slabbert et al. (2024) in South Africa, which is based on two principles: a) establishing a water reuse-literate public and b) ensuring that public knowledge about water reuse is sustainable (i.e., embedded within societal values and behaviors and transferred across generations). This strategy emphasizes creating culturally sensitive, contextually relevant messages while addressing the technical, environmental, social, and policy dimensions of water reuse projects.

By providing comprehensive information about LGW treatment processes and the environmental and economic benefits of reuse systems, the public can develop an informed and balanced understanding of their safety. Such knowledge can drive a positive shift in public perception, increasing acceptance and adoption (Fielding & Roiko 2014). Additionally, community participation in the decision-making process is essential for achieving sustainable outcomes (Marks 2006). In the Colombian context, these promotional activities could be led by the commercial areas of public service providers as part of the efficient use and water-saving programs mandated by Resolution 1257 of 2018 of the Ministry of Environment and Sustainable Development.

Per capita water consumption for the study case was 166.25 ± 47.17 L per−1 day−1. Its magnitude was significantly affected by the home size and increased with the frequency of certain hygiene and water use practices (i.e., handwashing, tooth brushing, and toilet flushing).

We found high levels of acceptance to reuse LGW at the household level (74% of respondents), with more willingness to reuse evidenced for people with technical school or professional degrees (>71%). Age and gender were not significant determinants of social perception of LGW reuse. The main reasons for rejecting LGW reuse were health risks (94%), space requirement (56%), and odor emission (53%).

The preferred applications for treated LGW reuse included activities involving the least possible human contact with water, such as toilet flushing (67%), floor cleaning (81%), and watering gardens (67%). We observed that interviewed people were noticeably willing to invest in LGW reuse systems (73%), to perform operation activities from daily to weekly (77%), and to do maintenance activities from weekly to monthly (64%).

Finally, we identified five challenges facing LGW reuse at the household level in the Colombian context and strategies to overcome them, which include: i) development of regulations for implementing LGW reuse at the household level, ii) incorporation of aspects related to onsite LGW reuse systems in the study plans of various education levels, iii) development of financial incentives for encouraging LGW reuse, iv) technological development adapted to households' areas and conditions, and v) promoting LGW reuse systems for enhanced social acceptance.

The authors thank the residents of the La Victoria neighborhood in Bucaramanga for their willingness to participate in this study. The authors thank Universidad Industrial de Santander for the support received while writing this paper.

This study was partially funded by Universidad Industrial de Santander (grant no. 3953 of 2023).

Free and informed consent of the participants or their legal representatives was obtained, and the study protocol was approved by the Scientific Research Ethics Committee of the Universidad Industrial de Santander. 

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

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