Generation rates of greywater in Kuwaiti residential apartments

The generation rate of greywater is typically estimated from the results of questionnaire surveys that aim to obtain information about the frequency and duration of usage of sanitary appliances. However, this method is inaccurate and prone to human error. The purpose of this study is to present an innovative approach for estimating greywater generation rates from records of high-resolution flow meters used to measure household water consumption. Ultrasonic flowmeters and data loggers were installed in the main water supply pipes in bathrooms and kitchens on the roof of a three-apartment housing complex in Kuwait. Water consumption patterns were remotely monitored for nine months using data loggers that transmitted information every 5 s. The TraceWizard® software was used to break down the time series of water consumption into various usage events for toilets, showers, hand basins, and kitchen sinks based on predetermined water usage profiles (flow rates and durations). According to the results obtained, the average daily per capita water consumption was 238 L. Furthermore, black water, light greywater, and dark greywater represented 9 %, 50 %, and 34 % of the per capita water consumption, respectively. Additionally, the leaks and unclassified volumes of water used were 1 % and 6 %, respectively. Accurate information is essential for the development of successful greywater reuse projects that significantly reduce freshwater demand. • Many socio-economic factors affect greywater quality and quantity. • Greywater quantity can be roughly estimated using the questionnaire method. • Greywater amounts can be accurately estimated by measuring water use.