Water Use - Water Use—the Future

Although water itself can be neither created nor destroyed, its usefulness and availability can fluctuate dramatically. Both the quality and quantity of water resources need to be protected for the nation's present and future generations. Although current water use can be determined, total water needs for most uses are changing. Water use is dependent on prices, technology, customs, and regulations. Even though water-use data are good indicators of where and how the nation consumes water today, they are not necessarily good predictors of future water-use trends.

Although overall the United States is not running out of water, the era of free and easily developed water supplies has ended for much of the country; in some areas, water use is approaching or has exceeded the available supply.

Projections of freshwater usage by use-category are presented in the U.S. Forest Service publication Past and Future Freshwater Use in the United States (Thomas C. Brown, December 1999). According to Brown, by the year 2040 freshwater usage in the United States will reach 364.1 billion gallons per day. That figure represents a 7% increase over the 1995 usage rate of 340.3 billion gallons per day.

TABLE 2.9
Water use trends, 1950–2000
[Data for 1995 and earlier from Solley and others (1998). The water-use data are in billion gallons per day (thousand million gallons per day) and are rounded to two significant figures for 1950–80, and to three significant figures for 1985–2000; percentage change is calculated from unrounded numbers.] SOURCE: Susan S. Hutson, Nancy L. Barber, Joan F. Kenny, Kristin S. Linsey, Deborah S. Lumia, and Molly A. Maupin, "Table 14. Trends in Estimated Water Use in the United States, 1950–2000," in Estimated Use of Water in the United States in 2000 U.S. Department of the Interior, U.S. Geological Survey, March 2004 (revised February 2005), http://water.usgs.gov/pubs/circ/2004/circ1268/(accessed March 30, 2005)

	Year											Percentage change
	1950a	1955b	1960c	1965d	1970d	1975c	1980c	1985c	1990c	1995c	2000c	1995–2000
Population, in millions	150.7	164.0	179.3	193.8	205.9	216.4	229.6	242.4	252.3	267.1	285.3	+7
Offstream use:
Total withdrawals	180	240	270	310	370	420	440	399	408	402	408	+2
Public supply	14	17	21	24	27	29	34	36.5	38.5	40.2	43.2	+8
Rural domestic and livestock:
Self-supplied domestic	2.1	2.1	2.0	2.3	2.6	2.8	3.4	3.32	3.39	3.39	3.59	+6
Livestock and aquaculture	1.5	1.5	1.6	1.7	1.9	2.1	2.2	4.47e	4.50	5.49	f	—
Irrigation	89	110	110	120	130	140	150	137	137	134	137	+2
Industrial:
Thermoelectric-power use	40	72	100	130	170	200	210	187	195	190	195	+3
Other industrial use	37	39	38	46	47	45	45	30.5	29.9	29.1	g	—
Source of water:
Ground:
Fresh	34	47	50	60	68	82	83	73.2	79.4	76.4	83.3	+9
Saline	h	.6	.4	.5	1.0	1.0	.9	.65	1.22	1.11	1.26	+14
Surface:
Fresh	140	180	190	210	250	260	290	265	259	264	262	−1
Saline	10	18	31	43	53	69	71	59.6	68.2	59.7	61.0	+2
a 48 states and District of Columbia, and Hawaii
b 48 states and District of Columbia
c 50 states and District of Columbia, Puerto Rico, and U.S. Virgin Islands
d 50 states and District of Columbia, and Puerto Rico
e From 1985 to present this category includes water use for fish farms
f Data not available for all states; partial total was 5.46
g Commercial use not available; industrial and mining use totaled 23.2
h Data not available

By use-category the Forest Service projections anticipated increased freshwater usage for livestock, thermoelectric power generation, and domestic and public water services. (See Figure 2.8.) The quantity of water used by industry and for commercial applications and irrigation was anticipated to decline slightly over the period. Because water usage is closely linked to population size, one might assume that the population was expected to grow at a similar rate (7%) between 2000 and 2040. However, population growth was anticipated to be much higher (41%) over this period.

As a result, although the estimate for freshwater usage was for an increase of 7%, on a per-capita basis projections of freshwater usage actually anticipated a decline, from 1,254 gallons per day per person in 2000 to 992 in 2040.

Several factors are expected to contribute to the lower per capita freshwater usage rates. According to Brown, the two most prominent factors are (1) improved efficiencies projected for the municipal, industrial, and thermoelectric generating sectors, and (2) reduced irrigation withdrawals.

Increasing awareness among the traditional users of water and the general public of the finite nature of clean water supplies, particularly freshwater, has resulted in growing conservation efforts, and innovative approaches to water conservation and reclamation. Competition for use of this resource has increased in some areas, particularly between urban and rural users in the western United States. More and more off-stream users are abandoning the traditional pattern of using water once and then discarding it. Increased emphasis on more efficient delivery systems—recapturing water after use and treating it for reuse if necessary, recharging of aquifers, and the need to maintain base flows in streams and rivers—will affect future use.

Water Conservation

In "How We Can Do It" (Scientific American, February 2001), Diane Martindale and Peter H. Gleick described a massive water conservation project undertaken in New York. To prevent a pending water crisis in the early 1990s, New York City needed an extra ninety million gallons of water per day, about 7% of the city's FIGURE 2.6
Population and water use trends, by source, 1950–2000
SOURCE: Susan S. Hutson, Nancy L. Barber, Joan F. Kenny, Kristin S. Linsey, Deborah S. Lumia, and Molly A. Maupin, "Figure 13. Trends in Population and Freshwater Withdrawals by Source, 1950–2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, March 2004 (revised February 2005), http://water.usgs.gov/pubs/circ/2004/circ1268/ (accessed March 30, 2005) total daily use. Faced with the need to raise $1 billion for a new pump station to bring additional water from the Hudson River, the city came up with a cheaper alternative: reduce the demand on the current supply. Using a three-year toilet rebate program, budgeted at $295 million for up to 1.5 million rebates, the city sought to replace about one-third of the existing toilets that used five gallons per flush with the water-saving models that did the same job with less than two gallons. By the end of the program in 1997, 1.33 million inefficient toilets in 110,000 buildings had been replaced with low-flow toilets. The result was about a 29% reduction in water use per building per year. The low-flow toilets were estimated to save about seventy to ninety million gallons per day.

New York City saved 30 to 50 mgd (million gallons a day) of water from its leak detection program, 200 mgd from meter installation, and 4 mgd from home inspections.

Concurrently, New York City had a water audit program under which property owners who wanted to reduce water use to keep bills down could request a free water efficiency survey from the company that oversaw the city's audit program. Inspectors checked for leaky plumbing, offered advice on retrofitting with water-efficient fixtures, and distributed low-flow showerheads and water-efficient faucet aerators. Low-flow showerheads use about half the water of the old units. Faucet aerators, which replace the screen in the faucet head and add air to the spray, can reduce the flow from four gallons per minute to one gallon per minute. The company made several hundred thousand of these inspections, saving an estimated eleven million gallons of water.

Overall, the program has shown that water conservation works. Per person water use in New York City dropped from 195 to 169 gallons per person per day between 1991 and 1999, although the city's population continued to grow.

FIGURE 2.7
Water use trends by usage category, 1950–2000
SOURCE: Susan S. Hutson, Nancy L. Barber, Joan F. Kenny, Kristin S. Linsey, Deborah S. Lumia, and Molly A. Maupin, "Figure 14. Trends in Total Water Withdrawals by Water-Use Category, 1950–2000," in Estimated Use of Water in the United States in 2000, U.S. Department of the Interior, U.S. Geological Survey, March 2004 (revised February 2005), http://water.usgs.gov/pubs/circ/2004/circ1268/ (accessed March 30, 2005)

In Cases in Water Conservation: How Efficiency Programs Help Water Utilities Save Water and Avoid Costs (EPA, 2002), the EPA reported on conservation methods and incentives adopted by New York City and sixteen other North American locations. Each location was beset by problems such as a strain on the water supply, unaccounted-for water loss, and water shortages. One of the more significant conservation efforts took place in Gallitzin, Pennsylvania. In the mid-1990s the Gallitzin Water Authority reported water losses exceeding 70%. After identifying the major problems (high water loss, recurring leaks, high overall operational costs, low pressure complaints, and unstable water entering the distribution system), the water authority developed accurate water production and distribution records using seven-day meter readings at its water plant and pump systems. Then it developed a system map to locate leaks. A leak detector located 95% of leaks in the water system. After repairs were made there was an 87% drop in unaccounted-for water loss, and savings of $5,000 on total chemical costs and $20,000 on total annual power costs from 1994 to 1998.

Water Reclamation

The Water Department in Tampa, Florida, has been working to maximize the yield from its water supply. The South Tampa Area Reclaimed (STAR) water project featured the use of high-quality reclaimed water from the Howard F. Curran Waste-water Treatment Facility to satisfy the demands of high-volume irrigation users in South Tampa. Water would be made available through a water system that would be separate from the drinking water supply to prevent any possibility of cross contamination. The project began as a grassroots effort by Westshore residents concerned about future water supplies. Important conditions of the project were voluntary participation FIGURE 2.8
Water withdrawal by use-category, 1960–2040
[Data for 2000 and beyond are estimates based on middle population projections] in it; only citizens who wanted reclaimed water would have to participate in the project; and user fees would make the project self-supporting.

In the first four months of the project sign-up, 4,500 homeowners and businesses enrolled. Construction of Phase I began in 2002 and was near completion in 2005 at a cost of $28 million. The first users began drawing water from the system in July 2004. Recommended uses for reclaimed water are crop irrigation, lawn and landscape watering, washing cars, and general cleaning. The Water Department estimated that when fully operational, Phase I would save more than 3.2 mgd of potable water each day during the dry season, and additional phases are planned to extend the project to a wider geographical area.

The City of San Diego in California operates the San Pasqual water reclamation plant, located in the San Pasqual Valley near Escondido, California. The purpose of the plant, which can treat up to one million gallons of water per day, is to supply reclaimed water to the community. The wastewater received at the treatment facility is treated to the primary level when solids are removed. The screened primary effluent is then fed into as many as twenty-four aquatic treatment ponds where the wastewater is biologically stabilized. The ponds are stocked with water hyacinth, mosquito fish, crayfish, and other organisms to create an aquatic ecosystem that removes pollutants from wastewater. Water hyacinths grow quickly in the ponds. About 50% of the plants are harvested weekly from the ponds, dried for composting and sold for reuse as a soil amendment. After the water passes through the aquatic treatment ponds, it is clarified, filtered, and disinfected for use in irrigation and research.

FIGURE 2.8
Water withdrawal by use-category, 1960–2040 [CONTINUED]
SOURCE: Adapted from Thomas C. Brown, "Figure 16.1. Withdrawal Projections for the U.S. Using Middle Population Projections," in Past and Future Freshwater Use in the United States, U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, December 1999

Water Crisis Looming in the West?

Most of the fastest-growing states are in the West. (See Figure 2.9.) Census projections show that population growth in the United States for the first twenty-five years of the twenty-first century will be concentrated in states in the West and the South, especially California, Texas, Florida, Georgia, Washington, Arizona, and North Carolina, which were expected to gain more than two million people each by 2025. California alone was expected to leap by eighteen million over that period—by far the nation's biggest gain—which would boost that state from 12% to 15% of the country's population. With the casino building boom in Las Vegas and the surrounding areas, Nevada became the fastest-growing state in the 1990s and Las Vegas the fastest-growing metropolitan area. This population growth was expected to put enormous pressure on natural resources, including water, and to force huge changes in water consumption practices and prices.