Underbelly is getting wet when toilet is chocked open to fill the black tank

[JandJMorris2008]

Hi everyone, I'm hoping someone wiser than I can point me in the right direction here.

A while back I had dumped my black tank and was filling it back up to flush it by putting a chock in the toilet which keeps it open to fill. Anyway, my neighbor distracted me with some fish tales (LOL) and when I returned to check the status on the fill, I noticed a little water coming out from the underbelly covering (maybe a quart of water.... clear fortunately). I rushed inside to find, the tank had filled all the way up past the neck of the toilet and about 2/3 into the bowl and there was a bit of water (maybe 1/2 a cup) on the floor near the base of the toilet.

My assumption was that the seal at the base of the toilet leaked a bit due to the extra pressure of being filled so high. I pulled the chock out, went outside and pull the tank valve and drained the tank completely.

Since then, I hadn't used the chock to fill/flush the black tank and there hasn't been any issue, but over time I've noticed my tank sensors haven't been functioning as accurately as they had in the past so figured the black tank needed a better flushing than the internal sprayer provides and decided to try the chock fill method again.

I dumped the black tank, then started to fill it up with the chock in place. About 15 minutes into the fill I saw some water leaking out from the underbelly again and rushed inside to see if there was a problem. The toilet was fine (it's a Thetford Style II by the way). I shut the water off, and dumped the tank.

Since the water had not reached the plumbing that's visible from the toilet, my assumption was that the black tank, or the gate valve was leaking, so I dropped the coraplast cover from the underbelly and found that there was about a pint of water sitting on the foil insulation. Happy for me it was clear water!!!!!

So.... with the underbelly now exposed I thought I'd check for a leak and filled the black tank VIA THE INTERNAL SPRAYER and waited 20 minutes to see if there was leak........ happy days there was not!!!!

With no leak in the tank or gate valve present my question after that long build up is..... where the heck is the water coming from when I'm using the chock to hold open the foot pedal????

Secondly, I never replaced the toilet seal after the initial leak (the local RV repair shop said it wasn't necessary), so could this somehow be leaking, but not leaking to where it comes out on the bathroom floor and instead is leaking downward into the underbelly, or should I be looking elsewhere for leaks before I pull the toilet and replace the seal?

Any and all help would be greatly appreciate!!!!

Thanks

J. Morris

 

[cookie]

You didn't mention what model floor plan you have. There are more than one type of toilets used.
I don't know how your RV repair shop can say you don't need to replace the seal without looking at it.
Perhaps he was thinking rubber seal at the ball or blade.
I think you might want to pull the toilet and check the area where the toilet meets the plumbing. But then I am not looking at it either.
Why do you use a chock to fill your tank with water? Perhaps rather than doing that you might want to use the tank sprayer and then fill the bowl with your foot and then flush it a few times with the bowl full.
Just a couple of thoughts there.

Peace
Dave

 

[JandJMorris2008]

Thanks Dave,

It's a 3610RE, and the toilet is a Thetford Aqua-Magic Style II. The repair shop did look at it, but said they couldn't find a leak... This shop though was questionable in service though, so if they really looked it over carefully or not is questionable. Yet another reason to only have repairs/checks/etc. done at Camping World when possible. Sadly that was not an option in Galveston Texas.

As for why I fill it with the chock....... somewhere here in the forums here I had read that filling through the toilet provided a better cleaning of the entire system versus just the sprayer in the tank, and also (case in point) could uncover a leak that might otherwise go unnoticed.

The fact that I only get the leak if I fill through the toilet does add credence to that theory, but now it's a matter of figuring out where that dang leak is coming from.

Any thoughts on that?

Thanks again

J. Morris

 

[JohnDar]

With the relatively low pressure of running the water down the pipe by chocking the valve open, it's doubtful you're cleaning much. Repeated flushing of a full bowl of water would probably do more, or fill a bucket with hot water and dump it down the commode while holding the flush open.

If the seal was bad, you'd notice the bowl not holding water. You might even hear it drip down the pipe. BUT, if the clamp that holds the bowl to the base is not tightened enough (or misaligned), you can get water leaking out and onto the floor. If yours has a removable cover on the base, take a look and see if water is running down behind it and through the floor into the basement.

Water coming out from the underside may also be the result of a leaking tank flushing system, in particular the anti-siphon valve hidden in the wall. Mine decided to crap out late this past summer and I had water running under my steps onto the main floor.

I'm basing this on how my Sealand #210 toilet functions.

 

[JandJMorris2008]

Thanks John and Darlene, The anti-siphon is (fortunately) inside the back of the toilet head itself so I think I'll pull the unit and check it all out as that sounds like the most likely culprit short of the flange seal.

Thanks again!

 

[JohnDar]

Are you sure the anti-siphon valve for the black tank flush is located in the toilet? Normally, it's mounted so that it's a few inches higher than the commode (and not part of it).


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[danemayer]

There are 2 anti-siphon valves. One is on the toilet so that if water goes up to the top of the bowl, it doesn't work its way back into the fresh water supply. The other is in the tank flush line, to prevent black water from working its way back into the water hose. It's usually mounted above the height of the toilet, and is usually located behind the shower.

 

[JandJMorris2008]

2 of them... darn. Well one is for sure on the back top of the toilet about 6 inches higher than the bowl itself. The other one..... well that would be a very good question. I don't think it could be in the shower area because the plumbing is on opposite walls and across from each other but if there's a second one, it might be up in the wall behind the toilet. Not sure how I'd get to that one but I'll look for an access point before I pull the unit.

Thanks for the heads up, I'd have never known there were 2 anti-siphon valves!!!!!

 

[danemayer]

2 of them... darn. Well one is for sure on the back top of the toilet about 6 inches higher than the bowl itself. The other one..... well that would be a very good question. I don't think it could be in the shower area because the plumbing is on opposite walls and across from each other but if there's a second one, it might be up in the wall behind the toilet. Not sure how I'd get to that one but I'll look for an access point before I pull the unit.

Thanks for the heads up, I'd have never known there were 2 anti-siphon valves!!!!!

If you open up the plumbing area in the basement, you should be able to follow the pex line that is hooked up to the black tank flush inlet. That line goes up and there'll be a 2nd line coming back down, that goes to the black tank. On many floor plans, they go up on the off-door-side, by the water heater. If your shower is on the same side, it'll be behind the shower. There may be an access port in the shower wall to allow access to the shower water lines and anti-siphon valve.

 

[haulinem]

If you are over-filling the black tank then the water has two places to go, it will back up into the toilet since the seal is chocked open or into the roof vent for the black tank. If you have a joint in the roof vent it could be leaking from there into the underbelly. My guess is the water on the bathroom floor was the result of air burping out of the black tank as the bowl filled.

Just my guess
Terry

 

[JandJMorris2008]

Thanks Terry, I'm thinking it might be the siphon valve some folks mentioned because it only happens when I fill it from the toilet with the chock...... if I fill with the tank sprayer there doesn't seem to be a problem. Kinda thinking I should just forgo the chock fill method but since there is a confirmed leak during extended flush I'm concerned because I'm assuming that tiny leak over time could do damage or cause mold issues.

 

[danemayer]

Thanks Terry, I'm thinking it might be the siphon valve some folks mentioned because it only happens when I fill it from the toilet with the chock...... if I fill with the tank sprayer there doesn't seem to be a problem. Kinda thinking I should just forgo the chock fill method but since there is a confirmed leak during extended flush I'm concerned because I'm assuming that tiny leak over time could do damage or cause mold issues.

The Aqua Magic documentation mentions the possibility of a leaking anti-siphon valve as a cause of leaks. I've also heard of leakage in the middle, where the top and bottom halves of the toilet are joined.

If it's the anti-siphon valve, I would think you could check for leaks by wrapping it with tissue paper and holding the flusher down.

If it's the top/bottom joint, I'm not sure there's a way to fix it. You might give Thetford a call to see what they suggest.

 

[JandJMorris2008]

Thanks Dan and Ann, I'll check it out further with your suggestions. Would you happen to have a link for the Aqua Magic documentation you mentioned?

 

[danemayer]

Thanks Dan and Ann, I'll check it out further with your suggestions. Would you happen to have a link for the Aqua Magic documentation you mentioned?

In the manuals section of the forum, here.

 

[JandJMorris2008]

Awesome! Thanks!

In the manuals section of the forum, here.