Greywater (also known as graywater) is waste water from homes or commercial buildings that has not come into contact with any fecal matter and would be considered relatively clean. For the most part any water drainage NOT coming from the toilet could be considered greywater.

Common greywater sources include bathing, washing machines, dishwashers, etc… Clothes washers use roughly 25 gallons per load. The average bath in the U.S. uses up to 36 gallons. With just these two statistics it is easy to see how much water can be saved by implementing a greywater system in a household.

Benefits of Greywater Reuse:

  • Lessens the demand for fresh clean water on water systems
  • Lowers your water bill
  • Decreased load on local sewers
  • Potential initiatives to meet LEED or Living Building Challenge criteria
  • Reduced energy use and greenhouse gas production from water treatment plants
  • Enhanced drought resistance
  • Less impact on your septic tank.laundry to landscape

Although greywater may contain traces of dirt, househould cleaners, food, grease, and hair there are many safe and beneficial ways to reuse both treated and untreated greywater.

The most common reuse of greywater is for irrigation of landscaping and gardens. There has been many studies that show greywater has no negative effects on plants as long as cleaning product do not contain salts, boron, or chlorine bleach. The build-up of salts and boron in the soil can damage plants. A common cleaning product like ammonia can even be considered beneficial for plants because they use it to obtain nitrogen.

Another common use of greywater within the home is for the flushing of toilets. This alone can produce an estimated reduction of up to 30% in water usage for the common household.

The easiest and cheapest greywater systems that most people could do themselves is called “Laundry to Landscape”. Here is an informative video on this system.

If you are looking for a much “deeper dive” into how to implement a greywarter system you should view this 45 minute video from Google Tech Talks.


imageDavid Clemen

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