Do you think this water saving mod worthwhile?

[path1]

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?

[wrybread]

> 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...

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]

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]

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]

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]

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]

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]

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]

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]

http://www.marxrv.com/grwater.htm

[johnm1]

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.

[jrichard]

I've made this modification and it is very worthwhile for us as we were filling up the grey tank and occasionally running out of fresh water. We've never had an issue with black. From reading here, seems grey tank capacity is the most common limiting factor especially since carrying extra fresh water is easy.

It took our family of four from 3 days / 2 nights to 5 days / 4 nights with comfort (e.g. navy showers every night, careful but not crazy about water). With care and reducing the number of showers, we can go 5-6 nights fairly easily (...as a benchmark, our grey and black tank are each 34 gal and our fresh is, I believe, 40 gal). If we have access to camp showers and use camp toilets during daylight hours, I'm not sure how long we can go--we did 10 nights with no dump last year.

But you can't be stupid when you do this. First, you want backcheck valves (I used two just in case of failure...which I would never notice) on your fresh line near the toilet to make sure your grey does not back into your fresh. Second, IMHO, you want your connection valve at the toilet...the farthest possible from any outlet that you might use for drinking. Third, when you switch from grey water flush to fresh water for the toilet, you want to flush a lot of fresh water through the valve. Might not help, but it doesn't hurt and, when combined with backcheck valves, it probably adds some security. Fourth, obviously you want a valve that blocks all flow from the grey side to the fresh side so that you're never relying entirely on the back check valves...they're just for safety. That means your only source of potential contamination is bacteria that is on the ball of the valve. You probably have more nasty bacteria on your fingers from touching the door knob at the visitor center...and your fingers aren't exposed to a chlorinated bath.

Functionally, this system is a lot easier to deal with than using a bucket filled with your old dishwater or shower water. This is true especially for kids, but I don't think my wife would be thrilled if I said, "uh, well, we're storing a five gallon bucket of grey in the shower and I'd like you to use it to flush the toilet...be careful when you flush."

Cost...I'm not sure as I had some of the parts lying around. But it should under $200. The pump would be around $80, all valves another $50-60 if you use high quality stuff, then some hoses, fittings, wiring, fuses, etc. Installing it took me the better part of an afternoon.

Some mentioned odor as a potential problem. If the trailer has been sitting for a while, then it's an issue. Typically what I'll do is put a little blue chemical or a small amount of bleach in the grey tank when I pick up the trailer from storage. That kills the odor and it's almost never a problem for the remainder of the trip. If it stinks during a trip, a little blue chemical down the sink solves the issue.

In terms of clogging the pump, I filter before the grey water toilet pump...once with an actual filter and once with a mesh screen. I've had the system for 3.5 year using the trailer an average of 45 nights/year...never a problem with the pump. But cleaning the filter is a little nasty.

If you're thinking of doing this mod, fee free to PM and I can give more details on how I set it up, how I'm pulling from the grey tank, etc. If done right, it's safe and it will dramatically increase your effective grey and fresh water capacity.

[doxiemom11]

5 years, fulltime - NO CHEMICALS - just lots of fresh water when flushing. No odor, no clogs, no problem. Chemicals are perfume for you and if your system is working properly, there will not be any odor.

I wouldn't do good at boondocking more than 3 days. I like to be clean and would still want at least a military shower most days. Sink bath okay sometimes, and I sure appreciate a 2nd shower when it's hot out and I am hot & sweaty by the end of the day.

[wrybread]

If you have serious water conservation issues this strikes me as a great idea. Hell half the world flushes their toilets with grey water. And in the case of an Rv it's super easy to separate the grey and fresh water systems, and furthermore there's no reason to have the fresh water system linked at all. On the off chance you're flushing before there's any water in the grey water tank just wash your hands first.

And if you're really squeamish about grey water, put a little bleach down the sink every now and again.

The best water saving feature I've ever done on an Rv was foot switch for my kitchen sink. That way the water only runs when I need it to when washing dishes. Probably doubles my boon docking water time.

[Earl_E]

He's not messing with the fresh water, if I'm reading it right. No danger. I just use a dishpan when washing dishes and then dump the water into the toilet. That by itself saves a lot space in the gray water tank.