Saturday when picking up a part for my trailer I ran into a guy that has the same model as ours but few years newer. We got talking and he told me how he extends his boondocking time via pumping his gray water to re-use in his toilet. TT has 2 gray water tanks, one for kitchen and one for bathroom (shower and sink) He hooked up a water pump to his bathroom gray tank then to his toilet. He can twist a valve and pump water from his self contained tank or twist valve the other way and can pump water from his bathroom gray tank to his toilet. Neither one of us had our TT with us. Just picking up stuff at RV place.While I think the idea has some merit I wonder just how much this would extend boondocking time. We very seldom we run out of space in the bathroom gray water tank. Black tank would receive same amount of use. For us, any extended time would because of water savings on the fresh water tank. Does anybody see any other downsides to this mod? I see the pump being a shorter life because of soap residue and hair? Of course, one could also just drain the gray water into a gallon jug and use it for flushing.Does anybody know how many gallons of water your toilet goes through when boondocking?

It's an interesting idea. I don't know if it's worth the expense/effort.You could have the potential smell of gray water in the toilet, and another pump to clog or fail.I think it would be just as easy to carry a couple extra 5 gallon jugs of fresh water.

I don't doubt that could be done safely, but personally, I'm not going to do any modification that in any way connects waste water to the fresh water system. It's just too icky to consider.Flushing doesn't use much as I'm sure you know. But I've not measured it. What I know is that I encourage using as much as reasonably possible when flushing. It makes for a well maintained black tank. I encourage DW to conserve in other places, not the toilet.

Interesting. You could always add a filter before or after the Grey Pump to catch the nasty stuff in the grey tank.

Wow I'd hate to smell his bathroom....

sch911 wrote:Wow I'd hate to smell his bathroom....Yeah, I was thinking that too. Also, it may stain the toilet bowl.

Do you think this water saving mod worthwhile? | Good Sam Community

wrybread
Explorer
Jun 22, 2016
> Interesting idea. Might be useful if there was ever an
> RVer on the planet who knew the REAL level of their RV tanks. I guess
> you'd know when the black tank was full when water came out the roof
> vent.

@TNG: you should check out this cool gizmo:

https://www.amazon.com/See-LeveL-Tank-Monitor-709/dp/B004A34I10/ref=sr_1_4?ie=UTF8&qid=1466617643&sr=8-4&keywords=rv+holding+tank+level

More info here:

http://www.modmyrv.com/2009/01/12/rv-holding-tank-monitor-system

Lots of other great info on that site by the way (modmyrv.com).
bpounds
Nomad
Jun 22, 2016
wrybread wrote:
...Remember that in your house the two systems are connected as well...

This is not true. If your house is built to code, every appliance that creates waste water is protected by a back-flow preventer or air gap. And those are NOT the same as a check-valve. Check-valves are not sanitary. An exception might be your dish-washer, depending on your local ordinances. We are required to have air gaps, but many places allow a high loop instead.

ewarnerusa wrote:
http://www.irv2.com/blog/2014/12/rv-grey-water-recycling-made-easy/

This link provides a diagram that helps visualize this kind of mod. It links to a kit you can purchase. Our old TT had a small grey tank and this mod may have been more attractive. Our current TT has 50 gallon fresh, grey, and black tanks so filling the grey tank too quickly has not been an issue.

Image from the link above.

The only way I would do this is, using the above diagram as an example, would be to remove the connection to the 3-way valve where the check valve is shown. Then you would have two independent water sources, and the twain shall never meet. Of course it would require having some gray water in your tank before using the toilet, but a couple of gallons would do it. And in a pinch you could use the bucket brigade.
ewarnerusa
Nomad
Jun 22, 2016
http://www.irv2.com/blog/2014/12/rv-grey-water-recycling-made-easy/

This link provides a diagram that helps visualize this kind of mod. It links to a kit you can purchase. Our old TT had a small grey tank and this mod may have been more attractive. Our current TT has 50 gallon fresh, grey, and black tanks so filling the grey tank too quickly has not been an issue.

Image from the link above.
TNGW1500SE
Explorer
Jun 22, 2016
Racerx11 wrote:
http://www.marxrv.com/grwater.htm

Interesting idea. Might be useful if there was ever an RVer on the planet who knew the REAL level of their RV tanks. I guess you'd know when the black tank was full when water came out the roof vent. ;)
wrybread
Explorer
Jun 21, 2016
Oh come on, its thoroughly simple to keep the two systems separated. If you're super concerned, use redundant backflow valves. Remember that in your house the two systems are connected as well. Besides, its the grey water system, not the black water (which means that technically its more sanitary than what's in your house), and in a closed RV system you should be sanitizing your fresh water tank every now and again anyway.

Surprised people on a DIY forum are having trouble comprehending this simple principle.
JaxDad
Explorer III
Jun 21, 2016
path1 wrote:
Saturday when picking up a part for my trailer I ran into a guy that has the same model as ours but few years newer. We got talking and he told me how he extends his boondocking time via pumping his gray water to re-use in his toilet.

Does anybody see any other downsides to this mod?

Wow, I can't believe somebody would actually do that, let alone think it's a good idea AND recommend it to others.

Basically somebody has knowingly connected their fresh water and their waste water together.

If that valve leaks even a tiny bit the Venturi effect could vacuum waste water into the fresh water system.

Hmmmmm, wash my butt, amongst other things, in the shower then wash my dishes and brush my teeth with the recycled water?

Ummmmm, NO!!!!
jrichard
Explorer
Jun 21, 2016
johnm1 wrote:
I'm confused where the concern is about contaminating the fresh water tank. Now please, I do understand that you don't want to mix grey or black water into your fresh but, the fresh water is already plumbed to the toilet from the factory. As long as one uses the proper parts and does a proper install, it should pretty much be no different than what's already there.

It's different in that there's an actual solid connection between grey and fresh. As originally installed, the fresh connection to the toilet is basically a nozzle at the back of the toilet that sprays water--so, while bacteria could get in there, it's not as likely as when there's a ball valve that rotates and causes, without a doubt, grey water to touch the fresh water line.

The issue, really, is will bacteria travel all the way to one of your drinking faucets or otherwise contaminate water that you will consume orally? IMHO, the answer is that the risk is trivial. Certainly it is significantly lower than other risks we all take every day wrt bacterial contamination.
jrichard
Explorer
Jun 21, 2016
Racerx11 wrote:
http://www.marxrv.com/grwater.htm

I thought about this type of setup and it'll help with grey water capacity, but using grey to flush the toilet is better because (1) you use less fresh water, (2) your black tank will last longer because you're not flushing with fresh and then transferring grey...you're combining the transfer from grey with flushing of the toilet.
Racerx11
Explorer
Jun 21, 2016
http://www.marxrv.com/grwater.htm
johnm1
Explorer
Jun 21, 2016
I'm confused where the concern is about contaminating the fresh water tank. Now please, I do understand that you don't want to mix grey or black water into your fresh but, the fresh water is already plumbed to the toilet from the factory. As long as one uses the proper parts and does a proper install, it should pretty much be no different than what's already there.