What is it?

     Gray water refers to the reuse of water drained from baths, showers, washing machines, and sinks (household wastewater excluding toilet wastes) for irrigation and other water conservation applications. Contrary to common belief, gray water is not a “safe” product—it contains bacteria and other potential pathogens. 

     Consequently, the potential reuse of gray water is a public health issue, not a water conservation priority. Gray water must not be confused with black water which is waste water from toilets, kitchen sinks, and dishwashers. Black water must be directed to the sanitary sewer or septic system. Gray water recovery systems allow you to reuse water to irrigate your lawn and landscape plants, used around the foundation of your house to minimize foundation movement, and/or be used in your toilets. This will help you save money on your water bills. Unlike rain, gray water is a constant and reliable source of water that should be harnessed. You pay for water once when it passes your water meter, why not use it as many times as possible. 

Some important points:

  • Gray water should never be stored for long periods of time, since we are constantly producing it and because of its ability to turn septic with a presence of bacteria
  • The gray water surge tank should have an overflow valve leading to the sanitary sewer or septic system to prevent overflow and flooding. Also, homeowners should have the ability to direct all gray water flow to the sanitary sewer or septic system when desired or when water is not needed in the quantities produced by the household.
  • A sand filter can be used to remove unwanted solid material and a pump transports the gray water to the drip irrigation system or to the toilets located within your home.
  • Keeping track of what goes into the gray water system is very important. Detergents that include bleaches, fabric softeners, enzymatic cleaning agents, and high salt concentrations should not be used. There are many cloth washing and cleaning products on the market today that can take the place of these cleaners and produce the same results.
  • Gray water is suitable for many landscape plants and currently academic research is being carried out to identify the long-term effects on plants.
  • The most economical way to install a total gray water system (a system that captures all of the gray water produced) in a house is to plan it into the construction of the house.  Retrofitting existing homes where the plumbing is located in a concrete floor is nearly impossible and is usually limited to recovering washing machine water only.