A Touch of Greywater
Written by: Duane Officer
About a decade back, a roommate of mine, who happened to be a water systems engineer, devised a pretty clever, elegant (if not pretty) system for reusing “greywater.” In this particular case it was from our washing machine but greywater is essentially any household waste water from laundry, sinks or bathtubs but not including that from toilets (which is referred to as “blackwater” and as one might well imagine, is considered high in undesirable pathogens).
Quite simply, my roommate re-routed our condominium’s washing machine’s discharge hose into a food-grade (clean of chemical residue or other contaminants) 55 gallon blue plastic barrel (pretty much the same type used for rainwater collection systems) with an ordinary sump pump located at the bottom. A solid garden hose was run from the sump pump’s discharge up from the basement and outside onto the lawn; where a perforated hose sprayed the water to the small patch of lawn in front of the condo building (a soaker hose would be the better choice for irrigating ornamental beds).
It would probably be prudent to consider and/or research numerous issues; such as proximity to wetlands, potential levels of contaminants contained in any detergents used which may be harmful to plant life (phosphates, degreasers, etc.) and any state or municipal restrictions on use of greywater for your community.
I can only attest that I used Arm & Hammer laundry detergent (and have no idea what the other 5 units’ worth of people who shared those laundry facilities might have used for detergents) but the lawn did not seem to suffer. If anything, our little patch did remain greener and more robust than those of surrounding condo sub-units (which had no irrigation). It bears mentioning that grasses do tend to tolerate higher levels of “grey” stuff than ornamental plants, shrubs and trees.
These days, numerous filtering and purification systems are available. Do a web search for “greywater treatment” or “greywater recycling” and the hits will keep on coming. Most systems for irrigation seem to employ a pre-filtering stage (basically a gravity-fed sand filter to remove coarser particulates) which then feeds into either raised or surface planter beds.
Purification stages are typically added to systems where the greywater is also (or exclusively) used to supply flush water for toilets (you could also direcly scoop used bath or dish water for such a purpose with a bucket). In any case, extended storage of unpurified greywater is not recommended as all sorts of undesirable micro-organisms flourish in the often warm waste water; a certain health risk.
Intricate systems with bypass and/or multi-zone valves may be of interest to new home builders or remodelers. If your laundry room is above ground level, you could probably omit pumps completely and let gravity do all the work!
In any manner it is implemented, however, re-use of greywater can help reduce the amount of water going to municipal treatment or private septic systems and possibly save money for those on public water systems.
