Treated greywater is safe for irrigation and does not pose a risk for gastrointestinal illness or water-related diseases, researchers at the Zuckerberg Institute for Water Research at Ben Gurion University of the Negev, Israel, have confirmed.
“No additional burden of disease was found among greywater users in this study, suggesting that greywater is not a major source of gastrointestinal disease,” Professor Amit Gross, told The Source. “Moreover, based on the survey, the majority of the suspected exposures which occurred prior to the onset of illness included activities that were not related to greywater reuse.”
Although small scaled, the study is believed to be the only long-term epidemiological survey undertaken for greywater reuse and could greatly improve water reuse and efficiencies in dryland areas. Moreover Gross stresses that previous reported quantitative microbial risk assessment (QMRA) results were more conservative than the findings from the current epidemiological survey and so can be used reliably for modelling risks associated with greywater reuse.
Study participants, made up of greywater users and the non- greywater control group, were required to complete a weekly health questionnaire for a year, as well as a preliminary lifestyle questionnaire to assess their exposure level to greywater or potable water used in garden irrigation.
Although greywater reuse is practiced worldwide, in some countries public health concern is a major obstacle towards widespread greywater acceptance.
“It is a significant quantity that accounts for about 30 to 50 percent of domestic water use; we believe that it is an important resource that can mitigate water scarcity, especially in arid regions,” added Gross. “This study is another piece of evidence demonstrating that responsible greywater reuse is safe and can be done with fairly low-cost and low-tech solutions.”
The researchers’ next steps include promoting more responsible on-site greywater reuse with larger follow-up studies to allow for adjustments–or in some places establishment–of current regulations and to ensure safe reuse.
