Residential water use in the U.S. and Canada

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End uses of water for households in the U.S. in gallons per household per day and percent of indoor use End Uses Pie 1.png
End uses of water for households in the U.S. in gallons per household per day and percent of indoor use

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. [2] 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.

Contents

Water use measurement

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). [3] 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 were about 89 gallons (337 liters) per person per day in 2010 [4] and 83 gallons (314 liters) in 2015. [5] 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. [6] [7] [8] [9] 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. [10] [11] 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. [1]

Indoor use and end uses

Distribution of average daily indoor water use across 762 households in the U.S. and Canada - Based on Water Research Foundation study Distribution of Daily Indoor Use.png
Distribution of average daily indoor water use across 762 households in the U.S. and Canada - Based on Water Research Foundation study

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). [1] 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, among other low-flow fixtures.

Toilet flushing

On average, toilets are flushed 5 times a day per person and represent the single highest use of water in the average home. Toilet flushing makes up about 24% of overall household water consumption (at average daily volume of 33.1 gphd or 125 lphd). [1] Currently, the average flushing volume for all sampled toilets is 2.6 gallons per flush (gpf) (or 9.8 liters per flush (lpf)). Future reduction in toilet end use will occur as more homes use low-flush toilets (1.6 gpf, or 6 lpf) mandated by the 1992 Energy Policy Act, or high efficiency toilets (1.28 gpf or 4.85 lpf) which meet the EPA WaterSense specifications. A recent study shows that about 21 percent of all toilets in 5 states (Arizona, California, Colorado, Georgia and Texas) have a flushing volume that exceeds 1.6 gallons/flush. [12]

Showering

In an average home, showering is the second largest water use after toilets. The average shower uses 15.8 gallons (59.7 liters) and lasts for 7.7 minutes at average flow rate of 2.1 gallons per minute (gpm) (7.9 liters per minute). [1] On average, in a household of average size (2.65 persons) 12.4 showers are taken each week. For comparison, a navy shower lasts only 2 minutes and can use less than 3 gallons (11.4 liters) of water. The most water-frugal approach is used by the crew of the International Space Station (ISS) who use less than 1 gallon (4 liters) to bathe. [13] For showerheads, the standard for maximum flow rate continues to be 2.5 gallons per minute (gpm) (9.4 liters per minute (lpm)) as set by the Energy Policy Act of 1992. However, manufacturers now offer ultra-efficiency showerheads with maximum flow rate below 2.0 gpm (7.6 lpm). Examples include a showerhead with flow rate of 1.75 gpm (6.61 lpm) at high water pressure and 1.45 gpm (5.48 lpm) at low pressure, or a showerhead with three pressure compensated flow rates (by non-removable pressure compensator) with options of 0.5, 1.0 and 1.5 gpm (1.9, 3.8, 5.7 lpm). A widespread use of more efficient showerheads (with flow rates of 1.6 gpm) would reduce average water use for showering by 2 gphd (7.6 lphd)(or by 8 percent).

Baths

In addition to showering, baths were recorded in 47 percent of the sampled households in which 2.7 baths were taken each week (or, on average, 1.3 per week across all sampled households). Each bath uses on average 20.2 gallons (or 76.5 liters) of water. [1]

Faucet flows

Water flowing through opened faucets (including kitchen, bathroom, utility sink faucets, and hose bibs) accounts for 19 percent (26.3 gphd, or 100 lphd) of total indoor water use in an average household where faucets are used 51 times per day. On average, faucets are opened for 30 seconds at a flow of 1 gpm (gallons per minute) and an average discharge of 0.5 gallons (1.9 liters) per each use. [1]

Clothes washing

Washing laundry is a significant use of water in the average home, accounting for 17% of the average indoor use. [1] The average size family washes 5.4 loads of laundry each week. Each load uses on average 29.3 gallons (111 liters) of water. According to EPA, a full-sized Energy Star certified clothes washer (with "water factor" - WF ≤ 8.0 gal/cycle/ft^3) should use on average 15 gallons (57 liters) of water per load, compared to at least two times that volume used by a standard machine. [14] Currently, about one fourth of American homes use less than 20 gallons (76 liters) per load, with the average volume of 31 gallons (57 liters) per load.

Indoor leaks

Leaks, or flows of water without a discernible purpose, were observed in nearly 90 percent of monitored homes. The loss of water through leaks accounted for 12 percent of average indoor water use. Estimated loss of water in average household is 6200 gallons (23,500 liters) per year. [1] Common types of leaks include running toilets, slow-leaking toilet flappers, partially opened or dripping faucets, and other cracked or open supply lines. [15] [16] While all observed leaks are included in indoor use, some leaks could occur on outdoor bibs or water features.

Dish washing

Dishes can be washed by hand in a sink or in an automatic dishwasher (DW), which was present in 84 percent of the end use study homes. The average American family washes approximately 1.8 dishwasher loads each week. [1] The average water volume per load was 6.1 gpl (23 lpl) and dishwashers accounted for about 1 percent of total indoor use. The EPA’s Energy Star Most Efficient 2017 dishwashers use 2.4 to 3.2 gallons (or 9 to 12 liters) per cycle. [17]

Variability of water usage

Distribution of average end use volumes across 762 households in the U.S. and Canada - Based on Water Research Foundation study Distribution of End Uses.png
Distribution of average end use volumes across 762 households in the U.S. and Canada - Based on Water Research Foundation study

Residential indoor water use can vary considerably across households depending on the number of residents (or more specifically, on the size and family composition of each household) and other circumstances (both systematic and random). It also depends on the contribution of the various domestic purposes of water use to the variability of total indoor use. The distributions of the observed average daily volumes for eight major end uses of water also shows considerable variability and a skew toward the right hand tails of the distributions (the data on the figure with distributions of end use volumes are truncated at 120 gpd to enhance the separation of the distribution graphs; in order to include all observations within the right tail of the distributions would require extending the horizontal scale to 560 gpd (to capture the maximum observed volumes of 553 gphd for leaks, 345 gphd for faucets and 223 gphd for toilets). Among the eight indoor end uses, five (i.e., leaks, toilet flushing, showering, clothes washing and faucet use) show pronounced right skew in their distributions that contributes to the “fatter” and longer right-hand tail in total indoor use. Significant reductions in some end uses of water could be achieved not only through the adoption of efficient technologies (i.e., fixtures and appliances) but also through consumers' small behavioral changes to reduce water use and wastage and by eliminating customer side leakage through automated metering and leak alert programs. [18]

Outdoor use

The outdoor residential water use includes landscape irrigation, filling and back washing swimming pools, water used through outdoor faucets (hose bibs) for washing pavement and cars, and other outdoor uses. Annual outdoor use in North American cities differs by climatic region and ranged from 13,000 gallons in Waterloo, Canada to 120,400 gallons in Scottsdale, Arizona. [1] The average outdoor use across 9 sampled cities in the Water Research Foundation study was 50,500 gallons per household per year or 138 gallons per day (524 liters per day). Nearly 17 percent of homes irrigate their landscapes in excess of theoretical irrigation requirement. If excess irrigation could be eliminated, the average outdoor use would drop by 8,200 gallons per house, or by 16 percent.

See also

Related Research Articles

<span class="mw-page-title-main">Greywater</span> Type of wastewater generated in households without toilet wastewater

Greywater refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. As greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. Greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath.

Sustainable living describes a lifestyle that attempts to reduce the use of Earth's natural resources by an individual or society. It is referred to as "zero wastage living" or "net zero living". Its practitioners often attempt to reduce their ecological footprint by altering their home designs and methods of transportation, energy consumption and diet. Its proponents aim to conduct their lives in ways that are consistent with sustainability, naturally balanced, and respectful of humanity's symbiotic relationship with the Earth's natural ecology. The practice and general philosophy of ecological living closely follows the overall principles of sustainable development.

<span class="mw-page-title-main">Flush toilet</span> Toilet that uses water to convey human waste down a pipe

A flush toilet is a toilet that disposes of human waste by using the force of water to flush it through a drainpipe to another location for treatment, either nearby or at a communal facility, thus maintaining a separation between humans and their waste. Flush toilets can be designed for sitting or for squatting, in the case of squat toilets. Most modern sewage treatment systems are also designed to process specially designed toilet paper. The opposite of a flush toilet is a dry toilet, which uses no water for flushing.

<span class="mw-page-title-main">Water conservation</span> Policies for sustainable development of water use

Water conservation includes all the policies, strategies and activities to sustainably manage the natural resource of fresh water, to protect the hydrosphere, and to meet the current and future human demand. Population, household size and growth and affluence all affect how much water is used. Factors such as climate change have increased pressures on natural water resources especially in manufacturing and agricultural irrigation. Many countries have already implemented policies aimed at water conservation, with much success. The key activities to conserve water are as follows: any beneficial reduction in water loss, use and waste of resources, avoiding any damage to water quality; and improving water management practices that reduce the use or enhance the beneficial use of water. Technology solutions exist for households, commercial and agricultural applications. Water conservation programs involved in social solutions are typically initiated at the local level, by either municipal water utilities or regional governments. Common strategies include public outreach campaigns, tiered water rates, or restrictions on outdoor water use such as lawn watering and car washing.

<span class="mw-page-title-main">Shower</span> Place in which a person bathes under a spray of water

A shower is a place in which a person bathes under a spray of typically warm or hot water. Indoors, there is a drain in the floor. Most showers have temperature, spray pressure and adjustable showerhead nozzle. The simplest showers have a swivelling nozzle aiming down on the user, while more complex showers have a showerhead connected to a hose that has a mounting bracket. This allows the showerer to hold the showerhead by hand to spray the water onto different parts of their body. A shower can be installed in a small shower stall or bathtub with a plastic shower curtain or door. Showering is common due to the efficiency of using it compared with a bathtub. Its use in hygiene is, therefore, common practice.

<span class="mw-page-title-main">Tap (valve)</span> Valve controlling the release of a liquid or gas

A tap is a valve controlling the release of a liquid or gas.

<span class="mw-page-title-main">Water heating</span> Thermodynamic process that uses energy sources to heat water

Water heating is a heat transfer process that uses an energy source to heat water above its initial temperature. Typical domestic uses of hot water include cooking, cleaning, bathing, and space heating. In industry, hot water and water heated to steam have many uses.

A plumbing fixture is an exchangeable device which can be connected to a plumbing system to deliver and drain water.

<span class="mw-page-title-main">Household</span> Group sharing accommodation and meals

A household consists of two or more persons who live in the same dwelling. It may be of a single family or another type of person group. The household is the basic unit of analysis in many social, microeconomic and government models, and is important to economics and inheritance.

<span class="mw-page-title-main">Water damage</span>

Water damage describes various possible losses caused by water intruding where it will enable attack of a material or system by destructive processes such as rotting of wood, mold growth, bacteria growth, rusting of steel, swelling of composite woods, de-laminating of materials such as plywood, short-circuiting of electrical devices, etc.

Water supply and sanitation in the United States involves a number of issues including water scarcity, pollution, a backlog of investment, concerns about the affordability of water for the poorest, and a rapidly retiring workforce. Increased variability and intensity of rainfall as a result of climate change is expected to produce both more severe droughts and flooding, with potentially serious consequences for water supply and for pollution from combined sewer overflows. Droughts are likely to particularly affect the 66 percent of Americans whose communities depend on surface water. As for drinking water quality, there are concerns about disinfection by-products, lead, perchlorates, PFAS and pharmaceutical substances, but generally drinking water quality in the U.S. is good.

<span class="mw-page-title-main">Water efficiency</span>

Water efficiency is the practice of reducing water consumption by measuring the amount of water required for a particular purpose and is proportionate to the amount of essential water used. Water efficiency differs from water conservation in that it focuses on reducing waste, not restricting use. Solutions for water efficiency not only focus on reducing the amount of potable water used but also on reducing the use of non-potable water where appropriate. It also emphasizes the influence consumers can have on water efficiency by making small behavioral changes to reduce water wastage, and by choosing more water-efficient products.

<span class="mw-page-title-main">EPA WaterSense</span>

WaterSense is a program sponsored by the U.S. Environmental Protection Agency (EPA), designed to encourage water efficiency in the United States through the use of a special label on consumer products. The goal of this program is to protect the future of the U.S. water supply. WaterSense maintains partnerships with key utility, manufacturer and retail partners across the United States. WaterSense is voluntary, rather than a regulatory program. The EPA develops specifications for water-efficient products – low-flow fixtures – through a public process. If a manufacturer makes a product that meets those specifications, the product is eligible for third-party testing to ensure the stated efficiency and performance criteria have been met. If the product passes the test, the manufacturer is rewarded with the right to put the WaterSense label on that product.

A low-flush toilet is a flush toilet that uses significantly less water than traditional high-flow toilets. Before the early 1990s in the United States, standard flush toilets typically required at least 3.5 gallons per flush and they used float valves that often leaked, increasing their total water use. In the early 1990s, because of concerns about water shortages, and because of improvements in toilet technology, some states and then the federal government began to develop water-efficiency standards for appliances, including toilets, mandating that new toilets use less water. The first standards required low-flow toilets of 1.6 gallons per flush. Further improvements in the technology to overcome concerns about the initial poor performance of early models have further cut the water use of toilets and while federal standards stagnate at 1.6 gallons per flush, certain states' standards toughened up to require that new toilets use no more than 1.28 gallons per flush, while working far better than older models. Low-flush toilets include single-flush models and dual-flush toilets, which typically use 1.6 US gallons per flush for the full flush and 1.28 US gallons or less for a reduced flush.

<span class="mw-page-title-main">Dual flush toilet</span> Flush toilet that uses two buttons to flush different amounts of water

A dual flush toilet is a variation of the flush toilet that uses two buttons or a handle mechanism to flush different amounts of water.

The California Green Building Standards Code is Part 11 of the California Building Standards Code and is the first statewide "green" building code in the US.

Niagara Conservation is a manufacturing company based in Fort Worth, Texas best known for its plumbing products and its water conservation efforts. Niagara Conservation also manufactures lighting fixtures, light bulbs, caulks, sealants, and weatherization products.

Water recycling showers are showers that use a basin and a pump to re-use the water during a shower session. The technology is used to reduce the use of drinking water and primary energy consumption for water heating. By lowering the (household) hot water demand, water recycling showers also allow for smaller heating appliances, like boilers, solar water heating systems and other HVAC solutions.

<span class="mw-page-title-main">Nonresidential water use in the U.S.</span>

Nonresidential water use refers to all uses of publicly-supplied (municipal) water other than residential use. The nonresidential users include industrial (I), commercial (C), and institutional (I) sub-sectors, which are often jointly designated as ICI or CII sector.

A low-flow fixture is a water saving plumbing fixture designed to achieve water savings by having a lower flow rate of water or a smaller quantity per flush. Some of these low-flow fixtures are faucets, showerheads, and toilets. In the United States a maximum water usage of conventional plumbing fixtures was federally mandated by the Energy policy act of 1992. Low-flow fixtures are designed to save water over conventional fixtures by having a lower flow rate while still maintaining satisfactory performance. The Environmental protection agency (EPA) WaterSense program has requirements for plumbing fixtures to achieve their definition for water saving low-flow.

References

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