Grey Tank Plumbing

[mountainlvr]

On my 2010 Fuzion 402 the galley, 1/2 bath sink and middle toilet are all plumbed together into the middle holding tank and marked as grey at the drain valve handle. Reading in the forums it seems that this is a fairly common practice with Keystone. Has anyone attempted to modify drain lines and tie galley and 1/2 bath sink into the front grey tank? I think that opening and closing the belly would be the most difficult part. Some 1-1/2 ABS pipe and fittings should be all that is needed + some labor of course. I have had some odor issues after transport and this is likely where it is coming from.

Good job on the forums much has been learned here.

Happy Camping!

[Festus2]

Your post above is similar to the one you recently posted in this same section (Fuzion Gray Tank Concerns).

As indicated previously, some of us are wondering how, according to your description of what is happening, it is possible for your 1/2 bath/toilet are plumbed into one of your gray tanks. There must be a valve that you have not yet found that diverts the toilet matter into a separate, black tank --- not a gray tank - that has both shower/sink water from the 1/2 bath plus the contents of your bathroom toilet.

Unless the folks at Keystone somehow got the drain lines screwed up, this should not be happening. It is not designed that way and not common practice at Keystone to have galley water/bathroom shower-sink water AND the bathroom toilet all go into a gray tank.

There has been some discussion about having washing machine water and bedroom sink/shower water empty into a single gray tank.

There has to be another dump valve that you have not yet found or there really has been a goof-up at Keystone with your unit.

[Jager]

+1 -- Ditto. I have never heard of this before. Worse case I'm not sure this would be legal, although I'm not sure what set of laws would cover something like this. At a minimum I think this is pretty dangerous. There are fairly strict laws concerning residential plumbing in a house, venting requirements, purple PVC pre-clean, etc . . . It would also raise some concerns for me as to how best to flush the black tank out? I (everyone?) empties the blank tank first. Then using the nice full grey tank open the grey valve to back flush into the black tank. I don't think I'd buy a trailer that has grey and black mixed together.

In general dealers are completely clueless so I would recommend calling Keystone directly and ask them if they actually plumb some model campers in this way. At least then you'd know if this was done intentionally or by accident.

[JRTJH]

There are two "possibilities" here that I think need to be addressed.

First, there are (and have been) a number of "outdoor kitchen sinks" that are plumbed into the black tank. This has been done for a number of years and many RV's with outdoor kitchens are done this way. I would not be overly concerned with a sink plumbed into a black tank (except for rapidly filling the tank with gray waste water). This doesn't really cause a "functional problem". Recently, a number of washer/dryer applications are also being plumbed into the black tank. I think the rationale for this is that most people, if "dry camping" wouldn't be using the washer, so the black tank is "safe" from excessive gray waste" and in "full hookup" camping, the extra gray water from the washing machine is actually a "good thing" in keeping the black contents "well liquefied".

Second, and I think a "problem in the works" is plumbing a toilet into a gray tank. The reason for my concern is that most gray tanks have a 1.5" or 2" slide valve and are connected to the main dump port with a small diameter drain pipe. Black waste tanks are plumbed with a 3" valve and drain system. Black waste won't flow with sufficient volume or speed in a small diameter drain and will be subject to repeated stoppage from large waste "clumps". For this reason, I'd be extremely concerned if I had an RV with a toilet plumbed to a gray tank. I would be much less concerned if I had a sink plumbed to the black tank.

So, I guess the real issue (from a functional standpoint) is where the toilet is plumbed, not where the sink is plumbed.

[Jager]

Methane can kill people. I know there are traps in sinks and all that but in a moving vehicle I would worry a little about the safety of having an inside sink and black in the same tank. Just my 2 cents.

[mountainlvr]

Gentlemen, I performed the test that was suggested in this forum. With the galley "grey" tank empty and the dump valve open I poured five gallons of water into the 1/2 bath toilet and it all drained from the open drain valve. Then I poured another five gallons into the 1/2 bath sink and it also drained from the open galley "grey" tank valve. After completing these two tests I poured five gallons of water into the kitchen sink and it also drained from the open drain valve on the galley "grey" tank. I agree this should not be the case but facts are facts all three of these devices are piped into the same holding tank.
When the holding tank flushing feature is used at the dump station water is directed into both the main "black" holding and the galley "grey" holding tanks.
I contacted Keystone via e-mail and did not receive a reply.

[Jager]

Well that is pretty definitive. Guess you at least know for sure now. Just wondering, what size is the drain valve and pipe for that "galley" gray ?

[JRTJH]

Originally Posted by Jager

Well that is pretty definitive. Guess you at least know for sure now. Just wondering, what size is the drain valve and pipe for that "galley" gray ?

That is my thought as well. If it's a 3" drain, it's a "black tank" with a "gray tank label". If it's a 1.5" or a 2" drain, and a toilet is plumbed to it, it's an error on the part of whoever installed it. A small drain simply won't drain a black tank.

[mountainlvr]

There are two 3" drains that drop through the belly about 5 feet apart. I did here from the factory and they say that there is a problem because they do not dump toilets into a "grey" tanks. The kitchen sink probably gets the majority of the water run through it. On a recent trip the galley "grey" tank was full in one day. Flushing the 1/2 bath toilet resulted in back flow because the kitchen sink had some water in it that would not drain. Factory says it needs to be taken to a dealer where it can be repaired. I think that Keystone is going cover the work.

[mountainlvr]

Folks,
Heard from the factory and they told me that is the design for this model. One tank handles the 1/2 bath toilet and all other grey water drains in that section of the unit. Thanks to all who provided their input.

[Jager]

Another very valuable piece of info from this board. Now I know to check this out before I buy another unit or model. Thanks for posting all this.