Reducing the burden of rural water supply through greywater reuse: a case study from northern Malawi

Greywater reuse has potential for non-potable applications that conserve freshwater resources in water-stressed areas especially in sub-Saharan Africa. The feasibility of reusing greywater for domestic activities in a rural area of Malawi, Africa, was evaluated from microbiological and public acceptance perspectives. Median Escherichia coli concentrations for eight domestic greywater sources (handwashing, laundry, runoff from a tap apron, bathing, cleaning a home/kitchen, cleaning a water collection container, washing plates and soaking vegetables) ranged from 100 to >20,000 colony forming units (cfu)/100 ml. Twenty-four of 47 greywater samples tested (51%) met the World Health Organization guideline for unrestricted use of greywater for irrigation. Pertinently, 80% (4/5) and 60% (3/5) of greywater samples from handwashing stations and bathing had E. coli less than the WHO guideline. Users reported greatest acceptance of reusing greywater for growing food and washing clothes, especially when the greywater source was bathing. Acceptance was closely tied to a household’s economic standing, geographic location, and first-hand knowledge of reusing greywater. Greywater reuse practices in rural areas, especially targeting bathing water as suitable from bacteriological and user perception criteria, can help mitigate the impacts of water stress in


INTRODUCTION
The World Health Organization (WHO) credits stress on global freshwater resources and demands associated with increasing populations as the main drivers behind an increase in the reuse of greywater for agricultural purposes (WHO ). Greywater includes domestic wastewater which is generated by sources that are separate from human waste such as bathing, laundry, and handwashing stations, i.e. unconnected from a toilet or urinal, and can result from around 80% of freshwater usage in certain residential areas (Jamrah et al. ). Reusing greywater for applications that do not require potable water supply, such as producing food and watering plants, has been seen to result in savings of freshwater resources that could be used for other beneficial purposes (Jamrah et al. ). Reduced pollution discharges, promotion of groundwater recharge and increased food production have also been identified as potential benefits of reusing greywater (Madungwe & Sakuringwa ). Economic benefits of water reuse can be especially pronounced in regions dealing with water scarcity and high potable water costs (Ghaitidak & Yadav ). In the case of residential schools in India, environmental and health benefits were valued to be substantially higher than the capital construction costs associated with installing a greywater reuse system for food production and flushing toilets (Godfrey et al. ). According to Hall et al. (), low-income rural households that use water for productive purposes such as raising livestock can benefit from multiple-use water systems (MUS), which are designed to provide water for more than one specific purpose.
Previous studies have determined that greywater quality is site-specific (Jamrah et al. ; Mohamed et al. ). The short-term flow and composition of greywater depend on the source, time period of water-use activities and products used in the greywater source, such as soaps or cleaning agents (Eriksson et al. ). Contaminants of concern in greywater reuse include conductivity, total suspended solids, levels of Escherichia coli, biochemical oxygen demand (BOD), chemical oxygen demand, pH, salinity and heavy metals (Jamrah et al. ; Finley et al. ; Mohamed et al. ). But greywater reuse also has human-dimension factors. As reported by Hespanhol (), 'Public acceptance of the use of wastewater or excreta in agriculture and aquaculture is influenced by socio-cultural and religious factors.' Ilemobade et al. () found in South Africa the acceptability of reusing domestic water was more favourable for toilet flushing than irrigation, with user perceptions of 'smell' and 'colour', as well as the value of savings in current water tariffs by the potable water saved being important. Additionally, Jamrah et al. () found respondents who were opposed to greywater reuse cited safety, environmental, and religious concerns more frequently than either of the perceptions that reuse would pollute groundwater or not be viable from a financial perspective.
In Malawi, the National Water Policy (Malawi Government ) promotes water recycling and reuse for urban and peri-urban areas, but does not specifically target rural areas. In rural northern Malawi, water source options include piped water and community handpumps (both machine and manually drilled) as well as household pointof-use water treatment (Holm et al. ). However, the water supply in Malawi is fragile and increasingly impacted by climate change, as characterized by frequent drought and floods (Pauw et al. ; Chidanti-Malunga ). Food insecurity is also a major concern in rural Malawi, linked to inconsistent rainfall brought on by climate change (Murphy et al. ).
The purpose of this study is to evaluate the feasibility of reusing domestic greywater in applications that reduce the burden of collecting potable water in rural communities as examined using household surveys, focus group discussions, and by testing water samples for the presence of total coliform and Escherichia coli in a rural area of northern Malawi. The study findings are applicable for northern Malawi and other water-stressed areas of sub-Saharan Africa.

METHODS
We surveyed 123 households and collected 47 domestic greywater samples in Traditional Authority (TA) Timbiri and Sub-Traditional Authority (STA) Nyaluwanga, which are located in the Nkhata Bay District of northern Malawi (Table 1). Focus group discussions were convened with members of the local Water Users' Association (WUA), who are responsible for managing water access in the study area. Respondent households were in proximity to the Chikwina-Mpamba gravity-fed water distribution system, which covers an area of approximately 57 km 2 and whose ongoing development has been supported by the non-governmental organization World Vision Malawi

RESULTS AND DISCUSSION
The study included 123 surveyed households, inclusive of 805 people. Eighty-eight percent (98/111) of respondents who answered the question reported it took 10 minutes or less to gather water from their primary water source, while the remainder either took 11-20 minutes (5%; 5/111) or did not know how much time it took (7%; 8/111). Eightyeight percent (108/123) of interviewees said that a piped water connection, from the gravity-fed distribution system, was one of their primary water sources. However, inconsistent service at the piped water sources was a commonly reported problem during both household surveys and focus group discussions which caused people to resort to alternative sources when piped water was not available.
Alternative sources were not quantified during this study.
The presence of E. coli was variable between domestic greywater sources (Table 2) and geographic areas (Table 3). Median levels of E. coli ranged from 100 colony forming units (cfu)/100 ml for handwashing stations to >20,000 cfu/100 ml for greywater from washing vegetables and cleaning a home/kitchen. Greywater sources also exhibited variability in levels of total coliform, with median concentrations ranging from 9,100 to >20,000 cfu/100 ml.
For greywater after cleaning a home/kitchen and washing vegetables, each sample contained >20,000 cfu/100 ml.
Total coliform bacteria come from a variety of sources and will regrow in untreated water, which means they are not strongly indicative of fecal contamination in greywater, unlike E. coli (WHO ). The WHO guideline for using greywater for the unrestricted irrigation of root crops that will be consumed without being cooked is an arithmetic mean of 1,000 E. coli colonies per 100 ml (WHO ).
For the questions about the willingness to reuse greywater that was generated by bathing, respondents from the areas of Tank 3 and Tank 4 were least willing. For the four cases involving greywater made by washing clothes, respondents from Tanks 3 and 4 showed the least willingness to reuse greywater for washing clothes and cooking, and ranked in the bottom three (out of six tank areas) for the remaining two cases. Conversely, respondents from Tanks 5 and 6 were the two most willing areas to reuse greywater in five out of the eight cases presented during interviews.
For each of the eight reuse cases, either Tank 5 or Tank 6 had the highest proportion of respondents either 'willing' or 'somewhat willing'. Results for respondents from Tank 6 may be skewed, due to the small number of interviews conducted in this area. Five of the eight reuse cases were found to be strongly related to the geographic area that respondents lived in, as determined by chi-squared tests.
Tanks 4 and 3 had the smallest proportion of respondents who owned greater than two accessories and had the fewest and third fewest proportion of respondents currently reusing water, respectively. Respondents in the Tank 4 area also reported the greatest average distance from their home to the nearest market town (7 km, N ¼ 19). These demographics are in contrast to Tanks 5 and 6, which had the highest proportion of respondents with more than two household accessories and also the highest proportion of respondents currently reusing water. This finding indicates that even in a limited geographic area, perceptions can vary. Households with greater relative economic wealth and greater familiarity with water reuse practices were more willing to find greywater reuse acceptable than households at the opposite end of those spectra.
In each of the reuse cases, the percentage of 'willing' or 'somewhat willing' respondents was greater among those who already reuse water, and for five out of the eight cases, the percentage was twice as much amongst households that are currently reusing water. Chi-squared tests revealed the relationship between current reuse and acceptability was statistically significant in five out of eight cases (growing food with water from washing clothes and each of the four scenarios involving reuse of bath water). This indicates the acceptability of reusing greywater is related to the source, final application, respondent's economic standing, geographic location within the system, and first-hand experience with greywater reuse. It should be noted that relationships associated with the tank area of a resident's household are not only determined by geographic area, but may also be affected by the quality of water service from the tank itself. Furthermore, in rural water systems, like the gravity-fed scheme in the study area, it cannot be assumed that source water is initially free of E. coli or fecal contamination, even before being used for domestic activities.
Sixteen percent (20/123) of respondents stated that they currently reuse water after it has been used once, with reported reuse applications including watering gardens or crops, bathing, and mopping. This is lower than studies in Bangkok which found 42% of respondents already reused wastewater (Jiawkok et al. ). Current reuse practices reported in the study area agree with findings from focus group discussions with members of the WUA responsible for managing the Chikwina-Mpamba gravity-fed system. WUA members reported that selected residents use wastewater for food production in gardens and that fruit trees had been planted at the outlets of tap aprons at multiple water points, indicating reuse of greywater is being done at a limited scale currently. (2/2) and 27% (8/30) of households were currently reusing water for some purpose, respectively. This contrasts with 11% (9/85) for those who had completed primary school and 17% (1/6) for those who had no schooling.

Concerns about water conservation and availability
were also seen at an institutional level. During focus group discussions, WUA members explained their desire to initiate metering of connections in the gravity-fed scheme, as they were aware of residents leaving taps running for long periods of time, while not actually using the water. During the course of the study, it was also discovered that residents in certain areas would periodically shut off downstream gate valves without authorization in order to increase the pressure in their portion of the system, when undertaking water intensive activities such as brick-making. These two pieces of information show there is an unmet demand for water (at least for certain areas and times) and that freshwater resources are being wasted in the system. The observations also suggest that a MUS approach could be beneficial in water-stressed areas of rural Malawi and would support the efforts of field practitioners.
system. Most study households were low-income, indicating that greywater reuse options should have a focus on low-cost solutions. Potential benefits of reuse should include the potential for increased food production, through irrigating fruit trees such as bananas and root vegetables, and income generation activities such as brick making. From a bacteriological quality standpoint, targeting reuse of bathing and handwashing water has the best potential, whereas greywater from cleaning a home/kitchen and washing vegetables has the least potential. From a user perception standpoint, willingness to reuse greywater was highest for the reuse of treated bathing water. While the public acceptability of making bricks with reused water was not quantified within the study area, using greywater for this purpose has the potential to make a positive impact as brick-making is a common income-generating use of water and has limited contact with food products. On-site treatment is recommended prior to any water reuse in order to reduce waterborne disease transmission risks. Future studies should be directed towards evaluating the public acceptability, financial impact, and microbial removal efficiency of various low-cost point-of-use greywater treatment options, including a pilot study of the best options in rural areas.
Further research would also benefit from testing rural domestic greywater for a wider variety of constituents, such as metals (sodium, magnesium, calcium, and toxic heavy metals), salinity, and organisms that are indicative of viruses and parasites, in addition to total coliform bacteria and E. coli. Successful greywater reuse practices in rural areas, especially targeting bathing water as suitable from bacteriological and user perception criteria, can help mitigate the impacts of water stress in sub-Saharan Africa.