Grey Water – No Longer a Grey Area

Grey Water – No Longer a Grey Area

The summer of 2012 played host to the worst American drought in over 55 years. Each week of extreme drought conditions brought devastation to farmers across the Mid-West, Great Plains, and the Rockies. Farmer’s had to choose between paying exorbitantly high water prices to irrigate and save their harvests, or cut their losses.  And due to water bans in some areas of the country, some farmers had their water supplies terminated by the DNR. To a less massive degree, residential and commercial properties also took some hits. Home and business owners desiring to have the best possible lawns and landscaping were left disappointed as much-needed civil water bans kept their sprinklers dry.

Palmer Z Indes Short-Term Conditions

Grey water (stormwater) management plays an enormous role in today’s society—an enormously lacking role. Annually, each of the United States gets an average of 37 inches of rainfall.  If a property manager tends one square-acre, there is an opportunity to harvest some percentage of the 1,004,698 gallons of rain water that will fall on the plot annually. With the proper systems in place, you have the power to harness and repurpose your otherwise uncollected stormwater.

Area Area
(sq. miles)
(sq. km)
Amount of Water
Amount of Water
1 acre .00156 .004 27,154 gallons 102,789 liters
1 square mile 1 2.6 17.38 million gallons 65.78 million liters
Washington, DC 61.4 159 1.07 billion gallons 4.04 billion liters
United States 3,537,438 9,161,922 61,474 billion gallons 232,700 billion liters

3 Shades of Grey

Grey water comes from bathroom sinks, showers, tubs, washing machines, crude collection rigs and storm gutters. Grey water collection systems are typically categorized into three groups: untreated, filtered and treated.


Untreated is the most common, most simple and least expensive system category. Untreated grey water systems have a history of surface or topical use (e.g. watering lawns, shrubbery, trees, and gardens), however, general concerns have been raised about the health effects that some untreated grey water may have on edible plants and fresh water sources. Grey water can host levels of bleach, food grease, phosphorus, fecal matter and non-biodegradable, detergent-laden washing machine water. These malefactors provide necessary apprehension about the topical use of grey water.

To avoid a degree of biohazard, many municipalities require all untreated grey water to be instantly deposited below the frost line to feed deep water plants only. Grey water that is stored for more than 48 hours often begins stages of fermentation, which transforms into very dangerousblack water.


Filtered grey water is the most popular form of grey water collection systems. Filtration systems can range from high-end pump filtering to low-end barrel skimming. Filtered systems most commonly use pumps to disperse the harvested water through a drip system. High-end, multi-stage filtration prevents the water from continually clogging the drip, however it does not prevent the spread of fecal matter in the water. For this reason, it is illegal to use untreated, filtered water in aerial sprayers (e.g. sprinklers). Some websites and experts claim that there is no fecal matter in filtered grey water. Presupposing that they are capable of erring, it is strongly advised that everyone treats filtered grey water as a finer, but still untreated, version of untreated grey water.

Maintenance plays a huge roll in operating a filtered grey water system. Regular filter cleaning and replacement is a primary necessity, because if you forget to clean what you have, it will not (properly) work.


Treated grey water is the best and final stopping point for reuse. Grey water treatment systems can carry a hefty price tag of $8,000 or more, but easily prove their worth when called upon. Treated grey water is sent through a course-to-fine filtration system, chemically treated (predominantly with chlorine tablets), put through a final UV-light cleanse and then stored in gas-tight containers. During use, treatment systems are even sophisticated enough to supplement a lack of treated grey water with fresh water to complete specific tasks (e.g. flushing toilets). Treatment systems are also capable of telling when stored grey water needs to be released in order to prevent a system backup. states:
Although some systems clean water to potable levels, no jurisdiction in the United States allows the use of site-treated water for anything other than toilets. Public treatment plants are monitored by the EPA; there’s no way to know if homeowners run their home-based treatment plants to the standards of a municipal sewer.

While no jurisdiction permits treated grey water to be used indoors for anything other than toilet water, it seems that filtered grey water is used for much more—albeit “under the table.”

Grey water is an excellent place for your company/family to begin conservation efforts.  Reusing grey water for specific outdoor projects and purposes can be a very efficient way for you to save water and money.  As a recap, read these five quick tips from New Mexico State University:

  • Apply grey water directly to the soil, not through a sprinkler or any method that would allow contact with the above-ground portion of the plants.
  • Root crops which are eaten uncooked should not be irrigated with grey water.
  • Plants that thrive only in acid soil should not be watered with grey water, which is alkaline.
  • Use grey water only on well-established plants, not seedlings or young plants.
  • Disperse grey water over a large area, and rotate with fresh water to avoid buildup of sodium salts.
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Fritz Kreiss

Fritz has been involved in energy procurement and the field of sustainability for close to twenty years, with expertise in alternative energy development including geothermal, wind and solar farm developments.

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