Greywater and/or Dual Plumbing System Purchase Tips

There are three levels of greywater system currently available. The table below (courtesy of Home Energy Magazine) briefly describes the features and cost (in 1995) of these systems.

Types of Greywater Systems Currently Available

System Type
Source of Graywater
Features
Cost
Low - tech owner or professional installation
Washing machine only
200 micron mesh filter

55 gal garbage can w/locking lid
$400 - $800
Medium-tech
Uses all graywater sources
Sump pump to pvc tubing

Subsurface drip irrigation

200-micron mesh filter

(2) 55 gal. storage tanks
$1,000 - $1,500
Fully automated Professional installation
Uses all graywater sources
Automatically back-washed sand filter

250 gallon storage tanks

Pumps at both source and tank/filter

3-way valve, backflow preventers

Microprocessor controls all flows

Backed by potable water
$2,500 - $5,000

Source: Bennett, Dick. 1995. "Graywater An Option For Household Water Reuse", Home Energy Magazine. July/August 1995.

Buyer beware is the message according to Oasis Design. These experts feel many claims by greywater manufacturers are overstated. Homeowners should consider the following points before purchasing a greywater system:

  • Most new greywater reuse systems are abandoned or achieve less than 10% reuse efficiency within five years.
  • Many greywater systems consume so much energy and materials to save a little water that the Earth would be better off if the water were just wasted instead.
  • The economic pay back time for the majority of complex (as opposed to simple) greywater systems is often longer than the system life.
  • The majority of "successful" greywater systems are so simple as to be beneath recognition by regulators, manufacturers, consultants, and salespeople (e.g. a garden hose hooked up to the bathtub drain).
  • Claims made for packaged systems are often greatly inflated. Some are very expensive and many don't work.
  • A web search on any variant of "greywater" will yield hundreds of sites, most of which could be used to illustrate the errors above. Many of these errors are recognizable from manuals of the early 70's, reprinted verbatim on the web as cutting edge, despite having been discredited in the field for twenty years.

Source: Oasis Design (accessed 7/3/01)

The bottom line is: research any system carefully before taking the leap into greywater.