Is it Greywater or is it Gray Water?

I Actually Found Three Different Spellings!

In my research effort, I found Greywater, Grey Water, and Gray Water.  Anyway you look at it it’s still the same.

The concept of using Greywater is disgusting to some, but its really OK!

If you thought about the way water has been sought out for years for gardening use you would realize that using excess household water for keeping your plants alive is really a natural thing to do.  There are some precautions you need to know about concerning the safe use of greywater. The following is from the 1996 published article, New Mexico State University Study Guide M-106 on the Safe use of Household Greywater.


The amount and quality of greywater will in part determine how it can be reused. Irrigation and toilet flushing are two common uses, but nearly any non-contact use is a possibility.

Greywater is suitable for irrigating lawns, trees, ornamentals, and food crops. Though irrigation methods in greenhouses may differ greatly from outdoor irrigation, several guidelines for use of greywater apply to both situations.

  • Apply greywater directly to the soil, not through a sprinkler or any method that would allow contact with the above-ground portion of the plants.
  • Root crops which are eaten uncooked should not be irrigated with greywater.
  • Plants that thrive only in acid soil should not be watered with greywater, which is alkaline.
  • Use greywater only on well-established plants, not seedlings or young plants.
  • Disperse greywater over a large area, and rotate with fresh water to avoid buildup of sodium salts.

In addition, when irrigating outdoors, apply greywater only to flat areas where runoff is not likely. A cloth bag attached to the end of the hose will help distribute water and also act as an additional filter. The filter will need to be removed and cleaned periodically (every three or four days).

In arid areas where dry grass or brush pose a fire hazard, homeowners may wish to plant a firebreak or “greenbelt” of a selected high-moisture species. Greywater is ideal for irrigating firebreaks, because it contributes plant nutrients in the process.

Remember that in most areas outdoor irrigation is a seasonal use for greywater, but greywater is produced throughout the year. If reverting to sewer or septic systems during the winter is not feasible, find uses that are possible during all seasons.

Toilet flushing can use considerable amounts of greywater, as it normally accounts for up to 50% of indoor water use. Poor quality greywater is not a problem if it is used to flush toilets, because the water goes into the sewer or septic system where it would have gone had it not been reused. Greywater should be pumped into the toilet bowl for flushing. DO NOT put greywater into the toilet tank. Greywater in the tank may not only cause the flushing mechanism to malfunction, but could be backsiphoned into the fresh water supply if water pressure decreases suddenly.

Lagoons or ponds containing greywater can grow algae to feed fish in a separate pond, or provide food for ducks and other waterfowl. Removal of the algae is necessary to keep the system aerobic and prevent foul odors. Ponds are often lined with concrete, stone, or plastic to prevent leakage. This method is a relatively inexpensive and easy way to recycle water, but requires some expertise to site and construct the lagoons.

With an automatic clothes washer, the wash water from a lightly soiled load, or rinse water, can be saved to wash the next load. When reusing laundry water for irrigation, do not use liquid fabric softener or detergents including softener (use softener sheets in the dryer instead). Water should not be reused if the laundry includes diapers. Wash water containing gasoline, diesel, or similar pollutants, should not be used for purposes other than flushing (DUH I added that).


Untreated greywater should not be kept for longer than one day, but adding two tablespoons of chlorine bleach per gallon of water will extend storage time somewhat (seems like thats a lot of Chlorine!). Try to use greywater the day it is collected or the high bacteria count will cause objectionable odors.

Observe these precautions when using untreated greywater:

  • Greywater containing sodium, bleach or borax can damage plants. For this reason, water from automatic dishwashers should not be used for irrigation.
  • Water used to wash cooking utensils in the sink may contain grease, fats and oils, and is not acceptable for greywater use.
  • If you plan to use water from your washing machine, avoid liquid fabric softeners and detergents with softeners. Use a dryer fabric softener sheet instead.

    Investing time and equipment in a system designed to filter, store, and possibly disinfect greywater may make water reuse a more convenient practice. Some questions to answer before building a treatment system are:

    • How much greywater will have to be treated? About 65% of domestic wastewater is greywater. Bathing and laundry can generate considerable quantities of greywater in a large household.
    • What contaminants are present? Greywater from the bathroom will have different characteristics than that from the kitchen (see figure 1).
    • What are the possible uses after treatment? The planned uses of greywater may call for more or less treatment. Some uses, such as outdoor irrigation, are seasonal; greywater is produced year round.
    • What is the soil type and depth to water table at your site? A shallow water table underlying sandy soil could be in danger of contamination.

    Answering these questions will help you decide what type and size of system to install. Because greywater treatment systems are not much in demand, you may have to design and build a system to meet your own specifications and needs. Options to consider for greywater treatment include settling tanks, disinfectants and filters.

What does your local Community allow?

Typically you can contact your Public Works department and find out what issues they may have with the use of gray water.  In Payson Arizona, Gray water is allowable for homeowners as long as its not derived from your toilets or kitchen sink!

Click to access Using%20Gray%20Water.pdf

National Geographic – Green Living:  Suggests that you can create an Oasis in your backyard.  Here is the article that describes what you can do in a step by step formula.  There are recommendations on “how to” and what things you need to look out for when installing a grey water system.  Well worth the read. See the full article below.

*Remember these are just suggestions:  Make sure you don’t have neighbors who might object to your efforts near your planting area.  The plants suggested are just that…suggestions.  Bermuda grass is an invasive and can take over whole areas.  Think more about flowering shrubs, fruit trees, shade trees or bunch grasses.  Think about what fits your needs and your climate.

Caution:  If you live in rural areas beware of the attraction an oasis may have to wildlife.  No one wants to attract in javelina, bears, coyotes or other fearsome creatures into their back yards!

Don't Invite the Bears

Don’t Invite the Bears

Javelinas don't make good pets!

Javelinas don’t make good pets!


About rsingram

Environmental Specialist, Disaster Reservist, Certified Professional in Erosion and Sediment Control, Para-Archeologist
This entry was posted in Economics, Gardening and Composting, News, Recycle, Water Conservation and tagged , , , , . Bookmark the permalink.

2 Responses to Is it Greywater or is it Gray Water?

  1. ashby says:

    Make sure you don’t use detergents with Borax in them if you water with laundry water. Borax is very toxic to plants.

  2. cmmarcum says:

    Didn’t know that ashby. Thanks for the tip. Add Dawn Dish Liquid to the list of do not use on plants.

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