Water Wise Redux

Approximately 26 billion gallons of water are used every day in the United States and as the population of the United States, and the rest of the world, continues to grow, water and other natural resources are being consumed at an increasing rate. Water management has traditionally involved the manipulation of water supplies, rather than focusing on altering water demand. There are many advanced techniques and devices to help conserve water, such as greywater reuse, rainwater collection, water-conserving landscaping and irrigation practices, the installation of low-flow fixtures and appliances, and proper swimming pool maintenance, but few are taking such measures. Water users can also conserve water through some common-sense strategies in the home. These wise water use methods include taking shorter showers, taking baths instead of showers, running only full loads of laundry and dishes, and being prompt in repairing leaky plumbing.

The first method of water conservation, and perhaps the one requiring the most investment and equipment on the part of homeowners, is greywater recycling. Greywater, or sullage, recycling is defined as the reuse of water from the sinks, showers, washing machine and dishwasher in a home. Greywater currently contributes 75% of total wastewater flow to domestic sewers. Most recycling systems involve a diverter valve which separates greywater and blackwater. Blackwater is sent to a conventional wastewater treatment system. Greywater is run through a filter, typically a sand filter, to remove any organic matter, then relocated on site either to be treated by a separate process or used as is. Common treatments include chlorination or iodine for disinfection.  

Untreated greywater can be used for several water consuming activities, most notably outdoor washing and irrigation. Some studies have shown no adverse effects on lawns or ornamental gardens where greywater has been used for irrigation. In fact, there is even evidence that nutrients found in sullage will promote better plant growth than typical chlorinated municipal water. However, it is recommended that the use of harsh detergents or cleansers, such as boron or bleaches, be discontinued if greywater is to be used for irrigation. Also, greywater use should be avoided on acid-loving plants, as most greywater is slightly alkaline due to soaps and detergents present. It is also possible that extended greywater use may elevate sodium levels in soils, causing drainage problems and potential damage to plants.

Another method of domestic water conservation is the installation of water-efficient appliances and low-flow plumbing fixtures. The most common devices are low-flush toilets, faucet aerators, low-flow showerheads, and reduced water-use washing machines and dishwashers. Faucet aerators alone can cut water flow through that faucet by 50%. Faucet aerators mix air with the water which serves to reduce splashing and cuts the flow.

Finally, internal Wise Water Use strategies involve changes in water use habits, including bathing and household cleaning. However, personal water use habits can be hard to change. A more effective Wise Water Use method is vigilance with leak detection and repair. A dripping faucet can leak up to 200 liters per day, while a leaking toilet can account for 16,000 liters per year. More practical methods can save additional water, though they may require considerably more investment both in time and money.

External water conservation is just as important as internal, as in some areas up to 50% of homeowner water use may be outdoors. Lawn care accounts for about 32% of residential outdoor water use. Up to 180 gallons can be needed each time a lawn is watered, which occurs several times throughout the growing season. One way to eliminate this need is to limit the amount of grass by planting trees, shrubs or ground cover which absorb much more rainfall and require less maintenance than turf grass. Where grass is planted, lawn watering can be limited to evening or early morning hours. Wind and temperatures are low at these times, lowering the amount of water loss through evaporation. Placing mulch around plantings can also reduce water evaporation up to 70%. Also, lawns mowed shorter than 2 centimeters are likely to lose more water to evaporation.

There is also a landscaping technique known as xeriscaping, which is most prevalent in warmer climates, such as the Southern and Western United States. The term xeriscaping is derived from the Greek word “xeric,” meaning dry. It involves the use of xeric plants in landscaping and is defined as “a landscape method that maximizes the conservation of water by using site-appropriate plants and efficient water use techniques.” It has been shown that a properly maintained xeriscape may only need about one-third the water of a turf-based landscape. One aspect of this technique involves placing plants together in groups based on their drought tolerance and irrigation needs. This allows for only certain areas of a yard to be watered when a need for water is indicated. Studies show that xeriscaping can contribute to a 20% reduction in water consumption when coupled with a few other conservation methods. Verbena, geraniums, dianthus and succulents are examples of plants used in water-conserving landscapes. When combined with aesthetic elements, such as gravel walkways or mulching, an attractive yet water efficient landscape can be produced.

Proper swimming pool maintenance can also help to lower water demand. Evaporation is the largest cause of water loss in swimming pools. The average pool can lose up to one inch of water per week through evaporation. This can be anywhere from 720 to 3,000 gallons a month. In sunny areas, such as California, a pool can even lose its entire volume of water within a year. The best way to limit water loss by evaporation is through a pool cover, which can reduce evaporation by up to 95%. Windbreaks around pools will help reduce evaporation on breezy days. Significant water is also lost from pools through splashing – about 25% that of evaporation. Ways to lower losses from splashing include diving board removal and lowering the water level in the pool.


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