Gray water for Toilet?

[Widget]

I'm thinking through connecting the toilet to use gray water in an effort to conserve and manage tank space. Probably overcomplicating going with a standard setup, but I wanted to see what people think.

My plan would be to plumb a line from the gray tank to the toilet supply line. Upstream of this "T" connection I'd add a backflow check valve to prevent Gray water from entering the fresh water system and further upstream beyond that would be a ball valve.

I'm considering this because I'm hesitant to go full on gray because there's a chance that without grey water we wouldn't be able to flush.

Now for the questions, how dumb is it to have a blended gray/fresh line into the toilet? We don't need to contaminate the drinking water. Anyone have a better way to plumb the setup? Bonus points for a solution that eliminates the manual ball valve and fully automates things.

[xrvr]

Do you have a gray tank? Otherwise anything is possible.

[AnnArborBob]

Never heard of this, but here are a couple of thoughts:

1. You will need a separate pump for the gray water since you don't want to mix gray and potable in the same pump.

2. Gray water can smell, consider that if you plan to use the gray for the small amount of water that you leave at the bottom of the bowl.

3. The amount of fresh water used in flushing the toilet is pretty minimal. Seems to me you are using a hammer to swat a fly.

As a simpler alternative, you might consider catching some of the shower water (before it gets warm enough to use) and some of your dish water in a container and use that in your toilet.

We camp off the grid quite a bit and rarely have any trouble finding and adding potable water to our fresh tank on an as needed basis.

Best of luck.

[HowieE]

You could not come up with a more impractical idea if you tried. Not only do you run the risk of infecting yourself but the possibility of contaminating the city water system. Back flow preventers FAIL. In case you forgot those that died from Legionella. That was a cross connection.

While that was before back flow preventers became common practice you should not run the risk.

If you are filling the gray water tank faster than you want consider crossing the tanks. I have run a connection from the top of the gray water tank to the bottom of the black water tank. When gray fills it flows over into the black tank. No chance of getting into the potable water system.

[OTRA15]

Ditto to most previous cautionary comments -- overthinking IMO -- health risks -- contamination of city water supply -- clogging toilet ball valve etc. (depending on model year) -- logistics of adding new pump into plumbing system -- and so forth.

If you have an abundance of grey water, get the adapter for a garden hose to connect to the main black/grey sewer discharge, collect the grey water in spare 1-gallon water containers on the ground, then hand carry them into the trailer to use to flush the toilet. Simple -- more work than I would want to do -- but a better KISS solution IMO.

Costs vastly outweigh the benefits . . . ?

[dcasr]

Current advice on grey water is to leave your GW line open to the sewer, with a dip built into it to catch enough GW to act as a P trap. Grey Water stored in your tank quickly smells pretty bad. As others have said, your idea is overkill. If you want to catch cold shower water before it warms up in a pan, go ahead. Same for kitchen sink water. That will give you a couple of "free" flushes. Beyond that, just don't go there. Enjoy.

[B00merang]

I was going to skip over this chain until I saw the promise of bonus points "Bonus points for a solution that eliminates the manual ball valve and fully automates things".
My solution for eliminating ball valves and fully automated things is....leave things alone!
There...its eliminated, you keep your (and others') potable safe, and you don't mess with your fine AS' resale value. Bonus points please....jon

[idroba]

Not only would you need a pump, but a good filter on the intake side of the pump as gray water has a lot of bits of stuff in it which will plug up the internal valve systems on any RV pump.

If you do it, the easiest way to avoid any cross contamination is to use a separate sprayer, like a sink sprayer, to fill and flush the water in the toilet from the gray water pump and tank. Don't try to make the cross connection possibility real.

[Widget]

Idroba, that's the best suggestion yet, if I really wanted to make it happen. Otherwise I think I'll go the bucket route if we want to really conserve.

I felt like it was a bit of hair brain idea but I had to ask.

[tjdonahoe]

Leave it alone, airstream spent a lot of money engineering what you have and $25 isn't going to make it better, who wants smelly dish water in the toilet, the lumps will probably plug up any valves....

[Air4563]

another thing to consider is the action of the additives you put in the black water tank to break down the solids and eliminate bad odors. Would soaps,bleach and other things in the gray tank render these additives ineffective?

[AnnArborBob]

Originally Posted by Air4563

another thing to consider is the action of the additives you put in the black water tank to break down the solids and eliminate bad odors. Would soaps,bleach and other things in the gray tank render these additives ineffective?

I hesitate to keep this thread going as the original idea is not practical or particularly useful, but in response to the specific point in the quote above, we put gray water in the black tank all the time. In particular dish water in an effort to extend our gray tank. Bleach might be an issue but I can't think of why anyone would get any significant amount of bleach in their gray water in the first place unless they are washing dirty diapers in the kitchen sink???

[JamuJoe]

I've found that a bit of dishwashing liquid serves well to keep the black tank clean. No need for those chemicals. Just the amount from washing our french press, coffee grounds included, down the toilet keeps the black tank fresh until the next dump (rarely more than a week). The surfactant in the dishwashing liquid, along with the agitation from towing, takes care of breaking down solids. The last liquid discharged down the slinky is foamy. It's worked for 347 nights of camping.