A non-partisan, neutral perspective supporting diversity in the color of water

Saturday, May 8, 2010

FUDing About Greywater Appears FONEY

My sources watching the State of Washington graywater rule making process tell me that Oregon is not alone when it comes to FUDing about greywater reuse due to the apparent "dangers" to groundwater, and particularly when it comes to using greywater for irrigating vegetable gardens. Check out this article where a Ph.D. student in horticulture at Penn State University is testing the "threat theory":

"Our global fresh water supplies are fast depleting, said Robert D. Cameron, doctoral student in horticulture. "So it is critical that we begin to look at alternatives on how we can take wastewater and turn it into a resource". Robert designed a small wastewater treatment system constructed of culvert pipes filled with "...alternating layers of porous rocks, composted cow manure, peat moss, tire crumbs, potting soil and crushed limestone".  He also planted vegetables and ornamental plants such as tomatoes, peppers, rosemary, basil and orchids in holes drilled along the length of the pipes. He then pumped about 45 gallons of wastewater from a washing machine to the top of the two pipes and what happened?

"As the dirty water trickles down the pipes, the tight mesh created by the soil, gravel and roots filters out pollutants"...and..."Additionally, bacterial colonies among the roots eat away the dissolved organic matter while layers of iron scraps or clay can be added to trap phosphorous"  (emphasis added).

Interesting results.  Sounds painfully similar to what the Greywater Guru Art Ludwig, as well as his colleague Laura Allen of Greywater Action, have been promoting for years. Soil, organic material, and plants do an effective job of treating greywater (and septic tank effluent, too, if one believes the researchers at the largest land-grant university in the US, The Ohio State University).

But why stop there?  Canadian researchers Sara Finley, Suzelle Barrington and Darwin Lyew published "Reuse of Domestic Greywater for the Irrigation of Food Crops"  in the Journal Water, Air, and Soil Pollution, Volume 199, Numbers 1-4 / May, 2009, pp. 235-245. The abstract pretty much says it all with respect to the results:

As global water resources decline, reuse of domestic greywater for the irrigation of home gardens is quickly becoming widespread in many parts of the world. However, the sanitary implications of reusing greywater to water edible crops remain uncertain. This study examined the benefits and risks associated with domestic greywater reuse for the purposes of vegetable garden irrigation. Untreated (settled only) and treated (settling and slow sand filtration) greywater collected from a family home was analyzed for basic water quality parameters over a period of 8 weeks. During that time, both greywaters were used to irrigate individually potted plots of lettuce, carrots, and peppers in a greenhouse. Tap water was used as control. Upon maturity, plants were harvested and the edible portions tested for fecal coliforms and fecal streptococci, common indicators for the presence of pathogenic microorganisms. Heavy metals were not detected in the greywater, but both fecal coliforms and fecal streptococci were present in high levels, averaging 4 × 105/100 mL and 2,000/100 mL of greywater, respectively. Despite these high counts, no significant difference in contamination levels was observed between crops irrigated with tap water, untreated greywater, and treated greywater. Fecal coliform levels were highest in carrots and fecal streptococcus levels were highest on lettuce leaves. However, contamination levels for all crops were low and do not represent a significant health risk. Plant growth and productivity were unaffected by water quality, owing to the low N, P, and K levels of the greywater. These results reinforce the potential of domestic greywater as an alternative irrigation source" (emphasis added).

Penn State indicates that the next phase of their research will focus on the beneficial reuses of the treated wastewater such as reducing a building's need for air conditioning (yikes!). Probably won't happen in Oregon due to the FUDing about aeration of greywater, but Wyoming might be interested in implementing this research during their two days of summer.


The fussing about with greywater reuse in the Pacific Northwest is starting to appear to be Fear Of Nothing Except Yourself (FONEY).

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