Residential end uses of water

Residential water use (also called domestic use, household use, or tap water use) includes all indoor and outdoor uses of drinking quality water at single-family and multifamily dwellings. These uses include a number of defined purposes (or water end uses) such as flushing toilets, washing clothes and dishes, showering and bathing, drinking, food preparation, watering lawns and gardens, and maintaining swimming pools. Some of these end uses are detectable (and measurable) while others are more difficult to gauge.

The approximate average quantities of water applied toward specific purposes have to be estimated because only total use of residential customers is metered and recorded for time periods of one month or longer (although the AMR and advance metering infrastructure (AMI) technologies allow for more frequent readings). In the United States, a nationwide compilation of these metered quantities by the United States Geological Survey (USGS) shows average domestic water deliveries (for both indoor and outdoor purposes) by public water suppliers to single-family and multifamily dwellings to be about 89 gallons (337 liters) per person per day. Since early 1980s, the increasing public interest in water conservation prompted questions about consumers’ water-using behaviors and measurement of average quantities of water applied to each domestic purpose. In mid-1990s, the first national study of residential end uses of water was conducted in the U.S. acquiring high resolution data directly from the customer’s water meter and analyzing flow traces to assign each measured water-using event to a specific end use. Several detailed studies of domestic end uses of water in North America and elsewhere followed. In 2016, an update study of residential end uses of water, sponsored by the Water Research Foundation (WRF) was completed and is the most current source of data on the various purposes of residential water use described here.

Indoor water use includes water flows through fixtures and appliances inside the house. The average daily indoor water use per household (averaging 2.65 people in the North American sample) ranged from zero to 644 gphd (gallons per household per day) and averaged 138 gphd, with standard deviation of about 80 gphd (or 521 liters per day and standard deviation of 300 liters). The equivalent average use per person is 52.1 gpcd (gallons per capita per day) or 197 liters per capita per day. Because the distribution of indoor use in the sample of homes is positively skewed, a more appropriate measure of central tendency is the median, which is about 125 gphd (or 472 lphd). Toilet flushing is the largest indoor use of water, followed by flows through kitchen and bathroom faucets, showers, clothes washers, leaks, bathtubs, other/miscellaneous uses, and dishwashers. Since the late 1990s, total indoor use has decreased by 22 percent, primarily due to the improved water efficiency of clothes washers and toilets.

...
Wikipedia