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Sunday, January 24, 2010

Everything BUT the kitchen sink?

I am in Macau this week for a meeting on groundwater projects completed as part of the Global Environment Facility.  On the 14 hour long flight from San Francisco to here I had much time to think about greywater, as well as review a book manuscript over 500 pages in length, discuss the meaning of the universe with environmental conflict resolution specialist Peter Adler who just happened to be on the same plane on his way to another water conference in Singapore, and finish reading another book that had been on my docket for months.  Now I am very concerned at how I will maintain my sanity upon the return trip in a few days!

The email discussion about kitchen sink wastewater and how it should fit (or not fit) into Oregon's portfolio of greywater continues with some excellent research and hands-on experience.  Recalling that the concerns focused primarily on elevated counts of coliform bacteria, and more specifically fecal coliform bacteria, one committee member provided a summary of research from a Swedish research group concluded that "Fecal coliforms, coliforms and E. coli can grow in graywater – thus they can not be used as indicator of pathogen risk....and that.... the greatest risks are from viruses...and that....risks are reduced by...no surface ponding...and no lawn irrigation."  A study completed by the University of Arizona found that ...."levels of fecal bacteria in soil are greater in graywater irrigated soil, influenced by method of application...and that...animals in household had no effect...and that...no Giardia or Cryptosporidium were detected."

Other committee members had informal discussions with greywater enthusiasts.  The Greywater Guru (see sidebar) offered the following observations and comments:  

The most regulator-friendly way to deal with kitchen sink water is a subsoil, gravelless infiltration galley, which would likely work stand-alone for vegetarian households and would last longer for meat eaters with a grease trap or mini (55 gallon) septic tank in line before the infiltration area. There is no reason this system wouldn't be fine for diaper wash water, as well. Grease is definitely an issue for LTAR, and infiltration galleys are more likely to suffer from biomat formation and clogging than mulch basins, so where grease is expected, a grease trap is a good idea. The soil filters out smells, so this is a non-issue. The same sort of infiltration has been used successfully for raw toilet effluent for up to thirty years in watson wicks, with barely enough soil to cover the infiltrators. It is worth noting that there is a long history of widespread application of raw kitchen effluent to the soil surface in "drain out back" systems --probably over a million systems, over decade of time---with no record of reportable disease outbreaks or waterborne illness, or groundwater contamination. In this context, calling in the PEs would be a misapplication of increasingly scarce resources (emphasis added)

And the Australians and Canadians following the Rainbow Water Coalition offered some other "food for thought" on the kitchen sink wastewater issue by indicating that the wastewater from a dishwasher is cause for concern due to the alkalinity of the water, thus potentially affecting soil chemistry.  Grease is apparently a non-issue since there are equipment specifically manufactured to capture grease from kitchen water, but my review of the equipment suggested that this might be better suited for commercial applications.  But this is important information as the "Oregon Way for Graywater" discusses the bigger picture of greywater reuse for commercial and industrial applications.

Returning to the permitting issue, I have been thinking about the feasibility of requiring the homeowner or other entity interested in greywater reuse to provide documentation that their homeowner's insurance covers claims against greywater reuse, much like the requirements that many states have for providing documentation of automobile insurance when renewing the registration of a car.  Or, I am curious if a bond could be purchased to cover the liability associated with greywater reuse.  Both of these requirements would make permitting much easier and cheaper than requiring the full-blown application fees and site evaluations that are currently in place for permitting facilities through the Oregon Department of Environmental Quality.  And ease and cheap costs would more than likely encourage more greywater reuse, which I think is the ultimate goal of the recently passed legislation in Oregon.

Perhaps a variant of the "Home Core" toilet might also be an answer to kitchen sink wastewater reuse. And perhaps it is time for Oregonians to rethink what goes down their kitchen sinks, too.


  1. We suggest and train kitchen employees to thoroughly wipe off the dishes before they enter the sink or dishwasher for washing. This practice takes a little longer but is less expensive than using a plumber to snake the lines. This should be a practice at home as well as in commercial kitchens.

  2. Todd,

    Permits are a vexed issue.

    We need to ask what the permit is actually for - plumbing or irrigation.

    If it is for plumbing, then why should a permit be required when the plumber is required by law to ensure his/her work complies with the regulations?

    In Australia, it is most common for the plumbers to be randomly audited, with about a 1 in 50 chance of on-site inspection (for all plumbing work, not just graywater).

    Or is the permit required for irrigation system compliance?

    The recent changes to Californian regulations illustrate this well.

    A 'laundry to landscape' graywater irrigation system (essentially connect a closed irrigation network directly to the washer machine outlet - which I dont agree with because of problems caused at the washer machine end), can be installed without a permit, IF an additional pump is not used.

    So a commercial laundromat can install a graywater irrigation system irrigating graywater from multiple washer machines, running non stop, does not need a permit (eg 3 machines 6 hours a day = 20,000+ gallons per month); but someone wishing to use a small pump to properly pressurize their home irrigation system does need a permit.

    Inside commentary was that once a pump is required, professionals would be required to install (this is incorrect, although to be fair they hadnt seen the new systems about to be available). The perplexing attitude (for me) is that a construction permit is required as soon as a pro becomes involved. Huh?

    Having said all of that, my company is pragmatic, so we are releasing a gravity irrigation dripperline system, that uses an interim barrel to take pressure off the washer machine pump. It works well, but not as well as a pumped system.

    Re Insurance / liability...

    Exactly what is being insured against - contraction of illness from a properly installed system (unheard of, and extremely unlikely), or flooding / illness resulting from negligent installation?

  3. G-man and Paul:

    I like the suggestion to "re-think" how one uses the kitchen sink wastewater. A little preparation can go along way towards reusing the water.

    I agree with the concerns regarding permits - why? But I am just one voice in the discussion group, so will continue to ask about it. The insurance and liability issue would be related to concerns of property damage to neighbors, sick pets, who knows what given the creative minds of conflict beneficiaries in the litigious arena within the US. I offered the bond/insurance concept as an alternative to a permit - the permit system is simply a means to track where a problem might occur.