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Graywater is gently used water that comes from laundry machines, bathtubs, showers and bathroom sinks. The great abundance of graywater and its water-intensive applications means it can be reused and reduce water bills.

Denver was the first Colorado municipality to allow graywater reuse. It is now legal all over the state since Governor John Hickenlooper signed it into law in 2013. Water conservation is a huge benefit of graywater reuse. It is particularly urgent now as Colorado’s Water Plan predicts that the state will face a significant water supply shortfall within the next few decades and lists graywater as a key conservation strategy.

Graywater sources include water discharged from:

  • Bathroom and laundry-room sinks.
  • Bathtubs.
  • Showers.
  • Laundry machines.

Graywater does not include water discharged from:

  • Toilets.
  • Urinals.
  • Kitchen sinks.
  • Dishwashers.
  • Non-laundry utility sinks.

Every time we shower or wash clothes, we make graywater that is usually disposed of. Residents can lower their water bills and conserve a valuable resource by making their systems compatible with graywater reuse. Graywater can perform two important, water-intensive functions: landscape irrigation and toilet flushing. A study by Greywater Action on residential graywater systems found that the average household saved over 14,000 gallons of water per year by installing graywater filtration systems in their homes without negatively affecting soil or plant health.

This brief video shows how a graywater toilet system works.

For more information on Graywater, its potential uses and installing graywater systems, contact the following City & County of Denver departments:

Denver Department of Environmental Health, Environmental Quality Division


Department of Community Planning and Development, Neighborhood and Inspection Services Division