How to Recycle Gray Water

Written by maryann ullmann
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Gray water is reusable household water from almost everything but the toilet. Your bathtub, sinks, dishwasher, air conditioner, washing machine, all produce grey water. Waste water from these sources can be reused to water lawns and gardens, thus conserving water and providing an extra source during a drought. Systems to recycle grey water in your house can be as simple as hand-carrying a bucket, to restructuring the plumbing and creating a natural filtration system.

Skill level:

Things you need

  • Buckets
  • Water pipes and hoses
  • Jandy valve
  • Drip irrigation system
  • Window screen
  • Wood mulch or sand
  • Pond liner
  • Gravel
  • Local wetland plants

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  1. 1

    Take an inventory of your grey water sources (excluding the toilet) and how much waste water they produce. For example, how many gallons does your washing machine use per cycle, and how many loads do you do per week? The average person produces about 30 gallons of waste water a day.

  2. 2

    Determine your grey water needs. One square foot of soil can handle about one half gallon of grey water per week.

  3. 3

    Choose a grey water recycling system. If your waste water output significantly exceeds your needs, you'll probably want to keep it simple and collect grey water in buckets. If your landscaping is extensive and you have the space, consider altering your plumbing and constructing a wetland filtration system.

  1. 1

    Use the cleanest water first. The cleanest grey water comes from the air conditioner, followed by the shower and bathroom sink, then the washing machine, and finally the kitchen sink and dishwasher. Use the cleanest water before other sources if you do not need it all. See Tips & Warnings below for details on keeping grey water clean and safe.

  2. 2

    Arrange buckets. Place a bucket under the output hose of the air conditioner. Bring a bucket into the shower with you to collect excess water. Disconnect the "P-trap" (The U-shaped pipe) from under sinks and place buckets underneath. Hook up the drainage hose from the washing machine to a hose draining into a large drum in the back yard.

  3. 3

    Hand carry collected water out to your garden. You can use a window screen to filter out food particles. Apply the grey water directly to the soil and not over edible parts of plants.

  1. 1

    Reroute the plumbing from grey water sources to a central output channel outside your house.

  2. 2

    Use a "Jandy valve." This is a three-way valve that can turn the water to your garden or route the water back to the city sewage system in the case of excess water.

  3. 3

    Design a system to carry the water to your garden. A drip irrigation system works well with grey water as it minimally depletes the soil. Make sure to use a good filter, however, as food particles can clog up irrigation hoses. Consider filtering the water through a constructed wetland.

  1. 1

    Choose a filtration system. This part is optional, but will ensure your grey water is as clean and safe to use as possible.

  2. 2

    Filter the grey water through a window screen or box of wood mulch or sand to remove food particles and some grease. You may choose to stop at this step or clean the water further.

  3. 3

    Build a small wetland. After step 2, direct the water into a trench lined with a pond liner, filled with gravel and drain water, and planted with wetland plants on the surface. These plants clean the water naturally. After the water filters through the trench, guide it to your chosen irrigation system.

Tips and warnings

  • Use biodegradable soaps and detergents.
  • Alternate use of grey water with fresh water to maintain soil health.
  • Use grey water first on ornamental plants and lawns and save available fresh water for edible plants.
  • Use compost to help restore the soil's pH balance, as grey water tends to cause sodium build-up.
  • You may also use grey water to flush your toilet.
  • Never use "black water," water from the toilet or any thing that may contain fecal matter, as this water contains e-coli and needs to go to a water treatment plant.
  • Check with local health codes to make sure your grey water system is in compliance.
  • Avoid detergents with softening powders, bath salts, chlorine, bleach, thinners and solvents, drain de-cloggers, grease and oil.
  • Do not use grey water on edible parts of plants.

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