Will greywater reuse really affect the sewer flow? Experience of a residential complex in Al Ain, UAE

Reuse of recycled wastewater is one of the most feasible unconventional urban water sources in the United Arab Emirates (UAE). The extraction and reuse of greywater might affect the water and sewer pipe networks by changing flow characteristics. Therefore, the research question is how much greywater can be reused without affecting the existing water and sewer pipe networks? A residential complex located in Al Ain, UAE, was investigated in this regard. Water pipe network, water consumption and sewer flow data were collected and scenario modelling was conducted using the EPANET software. It was found that 100% capture and reuse of greywater has no impact on the upstream water distribution network, but reduces the recommended design flow in the downstream sewer network. The modelling results show that about 50% of generated greywater (about 95 litres per capita per day) can be harvested without affecting the upstream and downstream water and sewer flow characteristics, respectively.