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Water conservation is a powerful yet underutilized drought mitigation tool that can stave off the severe water shortages, financial losses, and public safety risks that historically have been assumed to be an inevitable consequence of drought. Hundreds of hardware technologies and behavior-driven measures are available to boost the efficiency of water use: when implemented and put into action, they can drive down short-term as well as long-term water demands (Vickers, 2001).

For nearly every example of water waste and inefficiency that can be found in water systems, homes, landscapes, industries, businesses, and farms, there is a water conservation device, technology, or practice that will save water (Table 1) (American Water Works Association, 1996; Postel, 1999; Smith and Vickers, 1999; Vickers, 2001). Hardware measures, such as leak repairs, low-volume toilets, and more efficient cooling and heating systems, will result in long-term demand reductions and typically require one action only (installation or repair) to realize ongoing water savings. Behavior-oriented measures, such as turning off the faucet while brushing teeth, and other actions involving human decision making, typically realize savings on a short-term basis but not over the long term. Because behavior-oriented conservation measures often

Table 1 Overview of Water Conservation Incentives, Measures, and Potential Savings

End User Category

System (water utility)

Residential (indoor)

Lawn & landscape irrigation

Examples of Conservation Incentives & Measures

Low volume of system unaccounted-for water (maximum 10% of total production) System audit

Ongoing leak detection, repair, water loss control, and revenue recovery Metering and meter maintenance (e.g., correct sizing, calibration, timely replacement) Pressure regulation

Conservation-oriented rates, rebates, and program and policy incentives Toilets and urinals (low-volume, nonwater, composting, retrofit devices) Showerheads and faucets (e.g., low-volume, aerators, retrofit devices) Clothes washers and dishwashers (e.g., high-efficiency, full loads only) Point-of-use hot water heaters (e.g., homes with high hot water losses) Leak repair and maintenance (e.g., leaking toilets and dripping faucets) Conservation-oriented rates, rebates, and program and policy incentives Water-efficient landscape design (e.g., functional turf areas only) Native and/or drought-tolerant turf and plants (noninvasives only) Limited or no watering of turf and landscape areas (beyond plant establishment)

Efficient irrigation systems and devices (e.g., automatic rain shut-off, drip hose for gardens)

Minimal or no fertilizers and chemicals (e.g., to control excessive growth and "watering in")

Rainwater harvesting (e.g., essential uses and efficient irrigation only) Leak repair and maintenance (e.g., broken sprinkler heads and hoses)

Potential Water Savings Range

10-50

15-100

o ft

Table 1 Overview of Water Conservation Incentives, Measures, and Potential Savings (continued)

End User Category

Commercial, industrial, & institutional

Potential Water Savings Range

Examples of Conservation Incentives & Measures (%)a

Conservation-oriented rates, rebates, and program and policy incentives 15-50

Submetering

Efficient cooling and heating systems (e.g., recirculating, point-of-use, green roofs)

Process and wastewater reuse, improved flow controls Efficient fixtures, appliances, and equipment

Point-of-use hot water heaters (e.g., sites with large hot water losses) Leak repair and maintenance (e.g., hose repair, broom and other dry cleaning methods)

Conservation-oriented rates, rebates, and program and policy incentives 10-50

Metering of on-farm water uses (e.g., irrigation, livestock) Efficient irrigation systems and practices (e.g., surge valves, micro-irrigation, drip, LEPA, laser leveling, furrow diking, tailwater reuse, canal and conveyance system lining and management) Efficient irrigation scheduling (e.g., customized, linked to soil moisture, local weather network)

Land conservation methods (e.g., conservation tillage, organic farming, Integrated Pest Management)

a Actual water savings by individual users will vary depending on existing efficiencies of use, number and type of measures implemented, and related factors.

Agricultural

Sources: AWWA Leak Detection and Accountability Committee (1996), Postel (1999), Smith and Vickers (1999), Vickers (2001).

yield only temporary water savings, hardware and technology-based efficiency measures are favored by conservation managers, whose goal is permanent, long-term water reductions (Vickers, 2001). Case studies of efficiency measures implemented by individual end users among each major customer sector document not only water reductions, but also financial savings and other benefits (Table 2) (Adler et al., 2004; Bormann et al., 2001; DeOreo et al., 2004; Kenney, 2004; Ng, personal communication, 2003; U.K. Environment Agency, 2003).

The nearly 50% water demand reductions achieved by the city of Cheyenne, Wyoming, during record-breaking heat and minimal rain in the summer of2002 exemplify how adherence to simple and reasonable conservation practices can enable a drought-stricken water supply system to stay robust. According to Clint Bassett, Cheyenne's water conservation specialist, "We encourage everyone to keep conserving water" (WaterTech E-News, 2003). Lawn watering restrictions during one month alone—July 2002—lowered average demand to 18.1 million gallons (68.5 megaliters) per day (mgd) compared to 34 mgd (128.7 megaliters) for the same month in the previous year—a 15.9 mgd (60.2 megaliters) savings. Further, Cheyenne's reservoirs were 83.5% full in the summer of 2002 compared to 63% the previous year without conservation. Cheyenne's conservation program results created a water reserve or bank that enabled it to better withstand even more severe drought conditions had they occurred.

The implementation of water efficiency options in response to drought and long-term water shortages demonstrates the profound role these strategies can serve in abating projected supply shortfalls. Beyond temporary drought responses, in some cases the water demand reductions from multi-year conservation programs have served to minimize or cancel major water and wastewater infrastructure expansion plans and related long-term capital debt. For example, the average 25% system-wide demand reductions realized by the Massachusetts Water Resources Authority (MWRA) in the early 1990s as a result of a comprehensive and multi-year conservation program have been maintained for more than a

Table 2 Examples of Water Savings from Conservation

End User Category

System (water utility)

Residential (indoor)

Lawn & landscape irrigation

Measures Implemental

Water loss & leak reduction (Singapore): Reductions in unaccounted-for water (UFW) achieved through aggressive leak detection and repair, pipe renewal, and 100% metering (including the fire department). Active commercial, industrial, and residential meter replacement ensures accurate billing and minimization of unmetered water losses. Nonpotable water by industry is promoted and illegal connections can incur fines up to $50,000 or 3 years in prison.

Home building (Gusto Homes, England): Rainwater harvesting system and underground storage installed in 24 homes as well as dual-flush toilets, aerated showerheads, and solar water heaters.

Native plants and natural landscaping (CIGNA Corporation, Bloomfield, CT): Conventional 120-ha corporate lawn converted to meadows, wildflower patches, and walking areas by the CIGNA Corporation (Bloomfield, CT) .

Municipal drought lawn watering restrictions (8 municipal water providers in Colorado, U.S.): Outdoor watering restrictions were monitored to measure water savings achieved (comparison of 2002 drought year use to 2000/2001 average use), with the following results:

Reported Savings

System UFW reduced from 11% in 1989 to 5% by 2003, saving more than $26 million in avoided capital facility expansions

Average 50 m3/year per household water savings (50%)

Several hundred thousand dollars savings per year in reduced water demands, fertilizer, pesticide, and equipment and maintenance needs; estimated conversion cost was $63,000

Commercial, industrial, & institutional

Once/week maximum mandatory lawn watering restriction (Lafayette, CO)

Twice/week maximum mandatory lawn watering restriction (Boulder, CO; Fort Collins, CO; Louisville, CO)

2 V3 times/week (once every 3 days) maximum mandatory lawn watering restriction (Aurora, CO; Denver Water, CO; Thornton, CO; Westminster, CO) Voluntary lawn watering schedules (Boulder, CO; Thornton, CO)

Supermarkets (6 supermarket sites in Southern California, U.S.): Advanced water treatment systems reduced fresh water needs for cooling systems. Other recommended efficiency measures included: high-efficiency spray nozzles, aerators, and flow restrictors installed on hand sinks and spray tables; elimination of garbage grinders, to be replaced by composting food wastes; and installation of high-pressure sprayers to replace low-pressure hoses for the meat department.

Prison (Georgia Department of Corrections, Reidsville, Georgia, U.S.): Canning operation for vegetables (beans, carrots, greens, peas, potatoes, and squash) retrofitted with flowmeters, totalizers, and control valves to monitor water use. One rinse step eliminated and a counterflow rinsing system was installed to reduce freshwater requirements for cleaning vegetables. Alternative cooling system eliminated single-pass cooling water. Dry cleaning methods replaced water cleaning practices for floors and some equipment.

53% net water savings (average)

30% net water savings (average)

14% net water savings (average)

No water savings

(average); net increase in water use

2,700 m3/year average water savings per supermarket

94,600 m3/year average water savings (about 57% of peak daily use); capital cost of measures was $38,000 and estimated savings are $102,700; simple payback less than 1 year

Table 2 Examples of Water Savings from Conservation (continued)

End User Category

Agricultural

Measures Implemented

Dairy (United Milk Pic, England): Zero water use is the result of a reverse osmosis (RO) membrane system that was installed to recover and treat milk condensate for reuse throughout the plant.

Produce (Unigro, Pic, England): Producer of pesticide-free fresh fruit, vegetables, and herbs uses precision irrigation and rainwater harvesting in a sealed, climate-controlled facility that requires 30% less water per unit of crop yield than conventional irrigation.

Reported Savings

657,000 lirYyear; $405,000 per year

9,000 to 18,000 m3/year (50%) average water savings; $7,400 per year

Sources: Adler et al. (2004), Bormann et al. (2001), DeOreo et al. (2004), Kenney (2004), Ng, personal communication (2003), U.K. Environment Agency (2003).

decade, and they are projected to continue. Instrumental to this achievement were aggressive leak repair (the city of Boston could not account for approximately 50% of its water during some of the 1980s), innovations in industrial water use efficiency, and the installation of water-saving toilets and plumbing fixture retrofit devices. These conservation savings not only transformed that system's supply status from shortfall to abundance, but they averted construction of a controversial dam project on the Connecticut River that was projected to incur a debt of more than $500 million (1987 dollars) to more than 2 million-plus residents and businesses in metropolitan Boston (Amy Vickers & Associates, Inc., 1996). Should the MWRA need to reduce demands even further (i.e., respond to a drought, supply new users, or meet emergency water demands), a plethora of additional water efficiency measures can be implemented to increase water savings beyond the 25% already realized.

Water use reductions from conservation can be especially significant when drought response combines with multi-year conservation programs. For example, during a drought in 2001, the city of Seattle, Washington, provided water use curtailment messages to the public (in addition to existing conservation measures) and had a significant impact on water demand in 2002, yielding 1.2 mgd (4.5 megaliters) in new long-term savings. These reductions surpassed the city's 2002 water savings goals by 8%. Seattle's continuing water conservation program ("1% program"), which has a 1% per year water reduction goal to lower demand 30% by 2010, has thus far realized a 20% decline in per capita use. Seattle's savings are considered long term because they include hardware-based, more permanent efficiency measures such as system leak reduction; financial incentives for industries, commercial establishments, and institutional users that install recirculated cooling and efficient-process water systems; rebates for the installation of low-volume (6 liters per flush) toilets; high-efficiency clothes washers; and discounts for natural yard care products that minimize lawn watering (Seattle Public Utilities, 2003).

Water conservation should not be just an emergency response to drought, but a long-term approach to managing and alleviating stresses on the world's finite water supplies. The significant water savings potential from large-scale conservation programs is increasingly recognized as an alternative to conventional (and costly) water supply development projects, including desalination and wastewater reclamation facilities. In a research study by the National Regulatory Research Institute, research specialist Melissa J. Stanford (2002) affirmed a similar view:

Distribution system improvements, leak detection and remediation programs, water utility consolidation, wholesale purchasing agreements, demand management and integrated water resources planning, requests to conserve and water use restrictions, drought management planning and drought pricing, rate design alternatives, and communication and education are among the ways to bolster water supply and contend with drought. (p. 2)

In addition to the many benefits of conservation to drinking water systems, the recognition of ecological limits and the need to preserve streamflows through water efficiency and caps on use are also being incorporated into river and watershed schemes. For example, water extractions from the Murray-Darling river basin in Australia, that nation's largest and most economically important, have been capped to avert major damage to the river's ecological health. Even with the cap, the economy of that basin is projected to grow over the next 25 years (Postel and Richter, 2003), demonstrating that water efficiency is much more about boosting the productivity of water than sacrifice (Postel and Vickers, 2004).

Reducing water use is an obvious, in-kind response to drought and what nature presents: using less during times of shortfall, enjoying more in periods of natural abundance. "We all need to remember that water is not inexhaustible," remarks Bennett Raley (2004), assistant U.S. Department of Interior secretary for water and science. "Shortages will occur even in normal years. These shortages will threaten people, municipalities, farms, endangered species, and the environment. Doing nothing is not an option; it's not too early to start doing something about it now."

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