Grey Flush

wmarsha · 08-02-2009, 08:16 PM

I know this has been asked/answered before, but every search I do ends up with over 400 hits-it takes too long to check on all of them, and then we all do such a wonderful job of spelling, (grey? gray?, etc). So I am going to start a new thread.
Flushing the toilet with fresh water does not make sense to me.

many municipalities nationwide are changing plumbing codes to allow for secondary use of grey water. Usually it is for yard watering, but some instances allow toilet flushing to be done with grey water. Now in a house that obviously requires a grey storage system and pumping system. But in a AS, it's already there! Well, almost.

Most of the above code changes allow only bath, shower, and bath sink grey to be re-used. Kitchen grey water is not usually recycled at the individual house. Well, not yet anyway.

So, with the simple addition of a small gpm pump and some minor plumbing, why cannot the grey water be used to flush the toilet? Now as far as an RV is concerned the kitchen grey and bath grey and black usually end up in the same dump station. I am ignoring grey on the ground right now, because it really isn't germane to this discussion.

I feel confident there are many AS'rs that have made this modification, I am sure this ques has been asked and answered, just one more time for this newbie, okay? thank-you. BTW I have asked Janet to give me pointers on how to narrow my searches.
thanks, ya'll
ol' bill the newbie

bredlo · 08-02-2009, 08:41 PM

Great question, great idea for getting the most out of your on-board resources, and I look forward to seeing what others have done.

3 Dog Nite · 08-02-2009, 09:11 PM

RV'ers keep the grey & blackwater separate because of the enzymes & good bacteria. They help break down the solids in the black tank. The tank will clog up if solids stay solid. They can be combined in the dump station as most tanks will be pumped out & taken to a treatment facility. Soaps, alcohol from mouthwash, & other chemicals kill the enzymes & bacterias. Ricky

wmarsha · 08-02-2009, 10:36 PM

thanks, ricky, i think those are good points. to expand on my thinking a little: saves fresh water; saves grey tank capacity. I would think that a grey tank connection at a point where very few if any solids would be picked up would be best; the plumbing would include a strainer/filter in front of the pump. The existing fresh water connection to the toilet could be used with a hand sprayer to use fresh water rinse once in awhile. If eco-friendly "stuff" is used in grey water, I see no reason not to do this. Now, what if you had no fluids in the grey tank to flush with? well, again, the hand sprayer should get you past that situation. or, run a little water into the grey tank. after a more involved search i found some info on new AS's being equipped with only one holding tank. Not a good idea in my mind. Also, many folks say their grey tank fills up fairly fast...and do not like the idea of backing some grey into the black tank via a closed dump connection and open dump valves (both tanks). The question of whether or not grey water can be dumped directly onto the ground-both legally and ethically, is one each of us will have to face as we travel. BUT this mod would not affect that capability, as it puts grey directly into the black, not vice-versa. sounds like a future project-new pump for the regular system, use the old one on this mod...a little pex, a filter and there ya have it. Only problem is that dang belly pan...

TBRich · 08-02-2009, 11:45 PM

While in theory it may make good sense to use grey water for toilet flushing, there are some points to take into consideration:

1. Grey water tank contents, while certainly not as "toxic" as black tank contents, can get pretty foul, odorous, and with greasy buildup...
2. Grey water does have bacteria content to varying degrees, depending on the situation... (what went down the drains, how longs it's been in the tank, how warm it is, etc...)
2. Grey water does have some solid content (food particles, hair, etc) and any filtering system would probably require almost constant monitoring/cleaning in order to ensure water flow...

I'm sure there are other things that need to be considered if one thinks about it... Just some things to think about.

memgrove2000 · 08-03-2009, 08:30 AM

This sounds like a neat idea. You might want to look at a small "trash" pump. that would be able to handle the "solids" that might be in the grey tank. or a "macerator" type pump. Just a thought.