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Learn to Do Gray Water Recycling

written by: BStone•edited by: Donna Cosmato•updated: 5/20/2011

Reusing water from your home to water your garden is a great eco-friendly practice, saving you money while also preserving community resources. Learn all about gray water recycling.

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    What's So Great About Gray Water?

    Gray water is all the water that is produced as a byproduct of everyday household activities, anything from washing vegetables to taking a bath. Toilet wastewater is, however, excluded. Wouldn't it be great if some of this used water — which amounts to about 300 gallons of water a day for the average family of four — could be put to good use?

    Gray water recycling is the second use of this household byproduct. Water from cooking, cleaning and bathing becomes a source of water for your garden. Especially in drier climates or during periods of low rainfall, this eco-friendly practice is an invaluable tool for cutting down on water use, which saves you money and helps to preserve your community's clean water resources.

    Recycling the gray water in your home seems like an extremely practical concept. How is it done?

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    How to Reuse Household Water

    Reusing gray water can be a good move for you and the environment, if it is done correctly and responsibly. Water used for daily household activities may be carrying grease, dead skin, food particles, and chemicals from toxic cleaners and detergents. Doesn't this mean that gray water pollutes?

    When introduced to the soil, particularly the topsoil that is very biologically active, many of the substances in the recycled water are broken down by microorganisms, creating available nutrients for growing plants. The soil and plant roots serve to purify the water, to a point. The more organic matter in the soil, the more filtering power.

    Recycle Gray Water from the Shower To recycle used household water use the 'least gray' water first, such as shower and bathtub water, followed by water from the bathroom sink. If your irrigating needs are not yet met, use water from the washing machine next, followed by water from the kitchen. Using natural cleansing supplies, such as natural oil-based soaps and homemade products will of course cut down on the toxins in your gray water. If using water from the kitchen sink or dishwasher, try and minimize the amount of grease and food particles that make it into your gray water supply. Never use laundry water if baby diapers are machine washed.

    To move your recycled water to the garden for irrigation you can simply transfer the water by hand with buckets or a large basin. There are also irrigation systems that can be installed in your home by a professional plumber to carry gray water from sinks, the washing machine, or the bathtub to the landscape. Some of them are very simple, eco-friendly, and inexpensive.

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    Gray Water Tips

    While recycling your household water can be beneficial for the environment, the community, and you, there are some important things to keep in mind:

    • Only collect as much water as you can use for irrigation.
    • Gray water is best suited for shrubs and ornamental plants. Water Shrubs with Gray Water 
    • Do not water acid-loving plants.
    • Do not use for seedlings.
    • If watering your vegetable garden, do not water root crops or green leafy vegetables at all. Use only for crops in which the food is above ground, such as corn and peppers, and only in small amounts, rotating with fresh water. Never let the water directly touch the plants before being filtered.
    • Apply a layer of organic mulch to the area you are irrigating as this will help the decomposition process.
    • Apply directly to the organic matter, never spray or splash.
    • Spread the recycled water out over an area of flat ground rather than concentrating on one area.
    • Always rotate your gray water use with fresh water to help filter out chemicals.
    • If the soil is not rich in organic matter, it is not well suited for breaking down chemicals and other substances.
    • Gray water should not sit for more than 24 hours to prevent bacteria from forming.
    • Before having a system installed make sure you check with your state's rules and regulations about reusing water waste.

    Gray water recycling has many advantages. It is ideal for areas where there is not enough rainfall to keep the landscape irrigated. While soil that is rich in organic matter can act to purify gray water, constant use can harm the soil and plant life. Start small and light, using the least contaminated water. Place a bucket in the bathtub to catch running cold water while you are waiting for the water to warm up for your shower. Use the bathroom sink waste water from hand washing and teeth brushing. This may only amount to several gallons a day, but it is more then enough to irrigate your shrubs and flowers. There are many ways to cut down on water use in the house, and reusing gray water is only one of them.

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    References and Image Credits

    "Indoor Water Use in the United States" (EPA) <http://www.epa.gov/WaterSense/pubs/indoor.html>

    http://www.letsgogreen.com/greywater-recycling.html

    http://www.umassgreeninfo.org/fact_sheets/plant_culture/gray_water_for_gardens.html

    photo by Jeremy Levine Design

    photo by Kevin Gessner