The Water Efficient Home

Claudette Reichel  |  6/20/2008 1:04:55 AM

Treatment of drinking water and wastewater is increasingly expensive, even in high rainfall regions. Conserving water not only cuts your monthly water and sewer bill, it also reduces the public cost for water treatment capacity and slows the depletion of ground water supplies. Visit www.H2ouse.org to take the water efficient home tour and explore water saving opportunities in each area of your home.

More than half of household water consumption is for outside purposes. Avoiding the use of treated drinking water for watering plants and washing the car is first priority.

Xeriscaping and micro-irrigation: Xeriscaping is a term for landscaping in ways that do not require irrigation, with slow-growing, drought-tolerant plants to conserve water and reduce yard trimmings. Use native plants, mulch and other landscaping practices to minimize irrigation needs.

The ideal is not to need any irrigation, but if needed, a drip or micro-irrigation system uses far less water than sprinklers for shrubs, flowerbeds and gardens. A well-designed and operated sprinkler system (run at cooler times of the day) for the lawn can save water compared to manual watering with a garden hose. Systems are available that sense soil and weather conditions and irrigate only when needed.

Toilets and urinals: Although new toilets by law are low-flow, some perform far better than others. Check performance tests, such as results of the MaP test program at http://www.cuwcc.org/MaPTesting.lasso. High Efficiency Toilets (HETs) use only 1.2 gallons/flush or less, compared to the 1.6 gallon/flush government standard. New technology has enabled HETs to perform as well or better than standard flow toilets.

Residential urinals can use even less water than most low-flow toilets; some are waterless. More information and selections are available from several sources, including www.oikos.com and http://www.buildinggreen.com/.

Low-flow fixtures, aerators: Faucets and showerheads that surpass the government standard are available. Aerators inject air into the water stream, enhancing flow quality from faucets while reducing the flow rate of water. Laminar flow controls deliver a precise volume of water regardless of line pressure and a higher pressure feel by producing dozens of parallel streams of water. Kinetic water flow technology creates larger water droplets and a dense spray pattern to create a warm and strong feel.

Install 0.5-1.5 gpm (gallon per minute) flow controls in bathroom faucets, 1.5-2.0 gpm in the kitchen. and a 2.0 gpm for the laundry sink. Install showerheads with a flow rate below 2.5 gpm (1.5 – 2.2 gpm suggested), but with the feel of a higher flow rate and a guarantee against clogging. Aerators are not recommended in showerheads because of the cooling effect they create. Flow restrictor showerheads are unsuitable in areas with low water pressure.

Automatic faucets with a hot and cold water mixing control are available for homes. Although relatively expensive, they are convenient, sanitary and prevent the chance that the water will be left on (by accident or habit).

Washers: Most front-loading washing machines use far less water for the same size load of clothes and are more gentle and effective than most top-loading models. Dishwashers and clothes washers vary widely in water usage. Look for the ENERGY STAR label.

Structured Plumbing System: Plumbing systems should be designed to minimize the waste of water while waiting for hot water to arrive at the fixture. Options include placement of the water heater to avoid any long pipe lines; use of “home run” or manifold systems instead of fixture-to-fixture piping runs; and on-demand recirculating systems that are activated with a switch or motion sensor to provide instant hot water. Constant or thermostatically controlled recirculating systems are not recommended because they use more energy for recirculation and to continually reheat cooled water in the plumbing lines.

Rainwater harvesting: Rainwater captured from the roof is an excellent source for landscape irrigation and other outdoor uses. Water captured from a 2,000 sq. ft. roof in the Gulf Region can save more than 50,000 gallons of water per year.

The system typically requires properly designed gutters, piping, screens/filters and a cistern (enclosed storage tank) with overflow and distribution outlets. Nongranular roofings (metal, tile) reduce filter maintenance. Elevating the cistern 3-4 feet can provide enough pressure through gravity for a drip irrigation system; a pump is needed for sprinklers or non-elevated cisterns.

More detailed information about rainwater harvesting systems is available from Southface Energy Institute at www.southface.org and the City of Austin’s Sustainable Building Sourcebook at www.greenbuilder.com/sourcebook .

Greywater: Greywater is household wastewater from sources other than toilets and kitchen sinks, so it is relatively free of solids and contaminants, yet often rich in nutrients for plants. Since greywater is not potable (drinking quality) and could contain pathogens, its use is typically restricted by code to underground irrigation systems (not sprayers). Also, greywater reuse systems must have separate plumbing drains. A typical system distributes laundry water to the landscape Avoid laundry powders that may contain salt bulking agents).Two helpful information resources are www.greenbuilding.com and www.oasisdesign.net.

Before installing a greywater system, check with your local public health official to see if and under what conditions they are permitted. If greywater systems are not currently permitted but are desired (to reduce household sewage and water demand), you may still include separate plumbing in your new house for possible future greywater use.

Household sewage flow reduction system: Individual household wastewater treatment systems are used where access to community sewer lines is not available. The local public health official specifies the type of system that can be used on the site (see Pollution Prevention section). If a mechanical treatment plant is needed, a flow-reduction system can be used to irrigate a garden with the treated effluent (treated water discharged from the plant) in accordance with regulations of the state health department. This system may not provide enough water to sustain plant growth during unusually hot, dry months, but it still saves water.

Visit www.epa.gov/owm/ for more information on water conserving plumbing fixtures, irrigation systems and household wastewater systems.

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