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Water conservation 1960 USA postal stamp 4c

Water conservation refers to reducing use of fresh water, through technological or social methods. The goals of water conservation efforts include:

Sustainability - To ensure availability for future generations, the withdrawal of fresh water from an ecosystem should not exceed its natural replacement rate.
Energy conservation - Water pumping, delivery, and wastewater treatment facilities consume a significant amount of energy. In some regions of the world (for example, California ^[1]) over 15% of total electricity consumption is devoted to water management.
Habitat conservation - Minimizing human water use helps to preserve fresh water habitats for local wildlife and migrating waterfowl, as well as reducing the need to build new dams and other water diversion infrastructure.

Social solutions

Water conservation programs are typically initiated at the local level, by either municipal water utilities or regional governments. Common strategies include public education campaigns, tiered water rates (charging progressively higher prices as water use increases), subsidies for showerhead and toilet retrofits, and seasonalrestrictions on lawn sprinklers^[2]. Cities in dry climates often require or encourage the installation of xeriscaping or natural landscaping in new homes to reduce outdoor water usage "[1]".

One fundamental conservation goal is universal metering. The prevalence of residential water metering varies significantly worldwide. Recent studies have estimated that water supplies are metered in less than 30% of UK households^[3], and about 57% of urban Canadian homes^[4]. Although individual water meters have often been considered impractical in homes with private wells or in multifamily buildings, the U.S. Environmental Protection Agency estimates that metering alone can reduce consumption by 20 to 40 percent^[5]. In addition to raising consumer awareness of their water use, metering is also an important way to identify and localize water leaks.

Some researchers have suggested that water conservation efforts should be primarily directed at farmers, in light of the fact that crop irrigation accounts for 70% of the world's fresh water use.^[6] The agricultural sector of most countries is important both economically and politically, and water subsidies are common. Conservation advocates have urged removal of all subsidies to force farmers to grow more water-efficient crops and adopt less wasteful irrigation techniques(see Technological solutions below).

Technological solutions

Water-saving technology for the home includes:

Low-flow shower heads (sometimes called energy-efficient shower heads as they also use less energy, due to less water being heated).^{[citation needed]}
Low-flush toilets, composting toilets and waterless urinals, which can have a dramatic impact in the developed world, as conventional Western toilets use large volumes of water.
Faucet aerators, which break water flow into fine droplets to maintain "wetting effectiveness" while using less water. As a bonus, they reduce splashing while washing hands and dishes.
Wastewater reuse or recycling systems, allowing:
- Reuse of graywater for flushing toilets or for the garden, and
- Recycling of wastewater through purification at a water treatment plant. See also Wastewater - Reuse
Having 4-minute showers using an hourglass timer.
Waterless car wash

Overhead irrigation, center pivot design

For crop irrigation, optimal water efficiency means minimizing losses due to evaporation or runoff. An Evaporation pan can be used to determine how much water is required to irrigate the land. Flood irrigation, the oldest and most common type, is often very uneven in distribution, as parts of a field may receive excess water in order to deliver sufficient quantities to other parts. Overhead irrigation, using center-pivot or lateral-moving sprinklers, gives a much more equal and controlled distribution pattern, but in extremely dry conditions, much of the water may evaporate before it reaches the ground. Drip irrigation is the most expensive and least-used type, but offers the best results in delivering water to plant roots with minimal losses.

As changing irrigation systems can be a costly undertaking, conservation efforts often concentrate on maximizing the efficiency of the existing system. This may include chiseling compacted soils, creating furrow dikes to prevent runoff, and using soil moisture and rainfall sensors to optimize irrigation schedules.^[7]

Catchment management

Water catchment management measures include:

Recharge pits, which capture rainwater and runoff and use it to recharge ground water supplies. This helps in the formation of ground water wells etc. and eventually reduces soil erosion caused due to running water.

Water Conservation versus Water Efficiency