Special issue: NBS for resilient cities and communities — How understanding the micro components of domestic water consumption can provide multiple water uses to facilitate a transition to a Circular Economy of Water

Resilient cities and communities of the future will require a Circular Economy of Water (CEW), where used water is either reused with minimal treatment and/or separated at source, collected, treated and recycled on or off site to provide a “Fit for Purpose” water. Understanding the micro components of household water use and the different used waters generated is an important first step in this approach. This paper presents results from two separate studies. The first study monitored household water use in four households over a continuous 24-month period in Ireland. Meters were installed to monitor public mains water supply, toilet flushing, hot water, cold water supply to taps and water supply to kitchen. Daily water use profiles were generated. Per capita consumption rates varied from 71 L/hd/day to 132 L/hd/day. This compares to a national average in Ireland of 129 L/hd.d. These variations reflect the diversity between homes in terms of the way occupants utilise water for different practices (personal hygiene, laundry, kitchen, WC use). Averaging the results across all study households, for every 100 L of potable mains water supplied to the household, 28 L was flushed down the toilet, 22 L was used in the hot water system, 17 L was supplied to cold water taps for personal hygiene uses and 33 L was used in the kitchen. This study compares with results from an EU study compiled by the authors where over 75% of household water use across selected EU countries was also used for bathing and showering, WC flushing and laundry. Trends show that household water use has reduced across all selected countries in recent years. The influence of water meters in achieving this reduction is evident in the EU data. This effect is particularly evident from England and Wales, where water use in unmetered households is estimated to be 30% higher than metered households. The data shows that universal metering, increased water charges and a national focus on water efficiency and demand management programs can achieve significant reductions in household water consumption. The authors propose a Circular Economy of Water hierarchy focused on Reduce, Reuse, Recycle and Recover. A twelve step approach is suggested to facilitate this transition to a water smart society.