Common Questions about grey water

Any wash water that has been used in the home, except water from toilets, is called grey water. Shower, sink, and laundry water comprise 50-80% of residential “waste” water. This may be reused for other purposes, especially landscape irrigation.

NB : Kitchen Sink water is also classified as “dark grey water” and is only suitable for harvesting if the correct system is put in place. It is cautioned against harvesting kitchen sink water due to blood and meaty fats present.


It’s a waste to irrigate with great quantities of perfectly good drinking water when plants thrive on used water containing small bits of compost and organic waste. Unlike a lot of ecological stopgap measures, grey water reuse is a part of the fundamental solution to many ecological problems and will probably remain essentially unchanged in the distant future. The benefits of grey water recycling include:

  • Lower fresh water and/or drinking water usage.
  • Less strain and costs on failing septic tank or treatment plant’s
  • Better treatment (topsoil is many times more effective than subsoil or treatment plant)
  • Less energy and Less chemical’s to treat sewage
  • Groundwater recharge
  • Massive improvement on Plant growth
  • Reclamation of what would have been wasted nutrients
  • Increased awareness of and sensitivity to natural cycles
  • With the correct system installed grey water can be used for washing machine and toilet cistern water

In a nut shell, grey water systems don’t look that important. A new expensive low flow shower head can save you water with less effort. A septic tank system can treat grey water almost as well. But when you look at the bigger picture and how everything connects to one another, the keystone importance of grey water is revealed.

Ecological systems design is about context, and integration between systems. The entirety of integrated, ecological design can be reduced to one sentence: do what’s appropriate for the context.

Ecological systems such as : rainwater harvesting, runoff management, passive solar, composting toilets and edible landscaping, all of these are more context sensitive than their counterparts in conventional practice; that’s most of what makes them more ecological.

Grey water systems are more context sensitive than any other man-made ecological system, and more connected to more other systems.

Get the grey water just right, and you’ve got the whole package right, and that is what matters.

Many people and organizations instinctively recognize that grey water is the ideal test case for the transition to a new way of regulating and building that is appropriate to a post-peak resource, mature civilization.

The US Green Building Council, the City of Santa Barbara, CA, Oregon ReCode, and SLO Green Build are among those organizations which independently chose grey water standards as the technology with which to launch their programs of regulatory reform.


Yes Yes Yes. There are eight million grey water systems in the US with 22 million users. In 60 years, there have been 1 billion system user-years of exposure, yet there has not been one recorded case of grey water transmitted illness.


In practice, grey water legality is hardly ever an issue for residential retrofit systems,everybody just bootlegs them. However, grey water legality is almost always an issue for permitted new construction sites and/or remodeling purposes. For any further information on a Grey Water Harvesting unit suited to your home’s needs, please feel free in contacting us.