Zero Discharge Greywater Greenhouse

Subject: RE: "Zero discharge" greywater greenhouse
Date: Thu, 01 Jun 2000
From: Art Ludwig <Oasis Design>

M.H. writes:
> Hi, came across your site today, and believe I need some serious help
> regarding my wastewater greenhouse. Essentially, it's just not
> evapotranspirating fast enough, and I always wind up having to dump around
> 15 gallons a day outside (which I'd rather not do). The water I'm having to
> dump certainly isn't toxic--most of the time, it's already been filtered by
> the greenhouse before I have to get rid of the excess which collects in a
> catchment barrel once it's made the greenhouse rounds.
> I've spent the past year building my off-grid, timber-framed, strawbale home
> with attached 200 square foot solar greenhouse (measures 10 x 20 feet). The
> earth troughs are lined with vapor-barrier (I promised the State that it
> would be a zero-emission system), filled it halfway with
> sand, ran out a gravity-fed drain tile along the perimeter to a catchwater
> basin at the end of the greenhouse. Topped off the troughs with nice, black
> dirt, compost worm castings & manure, then planted all sorts of stuff.
> Bottom line: the plants are getting increasingly mature now, but the
> greenhouse is saturated. I still have 15 gallons of water I have to get rid
> of daily, which at this points averages my daily consumption of water.
> I had to get the State 's approval to build what they refer to
> as an experimental POWTS system (Private, on-site water treatment system).
> They granted approval contingent on my installing a holding tank in case it
> didn't work. I'm really tempted to simply start shuttling greywater into
> garden beds and whatnot, but want to live up to what I agreed to with the
> State. Furthermore, when I retire in another
> three years, I want to build environmentally-friendly homes for a living,
> which are 'blessed' by the state based on my experience with this home.
> It would be great to start a dialogue with you. As part of my agreement with
> the state, I maintain daily records of water consumption and frequency of
> appliance use, health, propane consumption, and ease of use. I'm happy to
> enclose a copy of the spreadsheet I'm using and a picture of my
> house/greenhouse, along with the application to the State.
> Hope to hear from you. Cheers.

Dear M.H.,
I think the original mistake was the "zero discharge" claim. I've never
believed this was either possible or necessary. The systems which make this
claim would more accurately be described as "pump out tank with ET assist."
I'd say you either have to:
1) Add a pump out tank to attempt to adhere to the original claim (although
even with this "remote discharge" would be more accurate than "zero
2) Dump your effluent without telling the State. This is a moral problem but
very unlikely an ecological or health problem.
3) Get the State to agree to dumping your purified effluent, perhaps with some
testing to show that it is within the standards for irrigation water, which it
probably is.
Good luck—let me know how it turns out.

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