leaking on a T@B 320s

What year '320 and do you have the Nautilus water system?

@spfrancis65, read through all the info in the below discussion thread, in particular the comments by @BrianZ.  I'm thinking that the connection/fitting for the water inlet valve is loose and needs to be tightened.  If you look at the photos near the bottom of the first page (and later) of the discussion, the black screw-on fitting on the interior side of the fresh water inlet valve is depicted.  It is not easy to get to, but you will have to reach your arm/hand down inside the compartment behind the toilet to get to that fitting.  Try to tighten it a bit as is described in the discussion.  Hopefully, that will stop the water leak.  You can use a small mirror and flashlight to help see into that area, but a flexible endoscope camera is the best way to view that area.  Fortunately, the discussion includes photos of the plumbing in that area, so that will help.  Good luck!

https://tab-rv.vanillacommunity.com/discussion/8617/fresh-water-leak-fixed-again/p1

See also this discussion:

https://tab-rv.vanillacommunity.com/discussion/8254/leaky-compartment-screenshot/p1

IMPORTANT NOTE:  You may already be using one, but if not, be sure to always use a water pressure reducer/regulator (set around 45 PSI) before connecting a water hose to the fresh water inlet.

There most likely is a plastic "check valve" attached to the shower connection in the bathroom. These are known to crack easily. I'd start there. Typically a black plastic fitting about two inches long in line with the hot water feed.

spfrancis65
Does the leak occur with the city supply off and the pump on?
If not, this narrows down the possible leak points to the area that Bayliss mentioned or nearby fittings.
If yes, as pthomas745 describes, there is a huge number of possibilities with some items being known more common problems.

spfrancis65 said:

that picture is worth a 1000 words...is removing the coroplastic a huge PIA to do.  That seems like the best place to start...to determine the root cause?

I have removed my coroplast cover twice.  Not really a PIA, and pretty straightforward, but takes some time removing all the screws.  They are faster to remove/replace with a power tool.  When replacing the cover, be sure to align the coroplast holes with the corresponding frame screw holes.

There are several aluminum "termination strips" of various lengths secured with the screws along the edges of the black coroplast cover.  As I recall, there were a couple locations near the axle/wheel that were a little harder to access, but I think I just had to approach the screw heads at a slight angle.

Since I had to remove all of the termination strips, I took the time to label the location of each on the backside with a black Sharpie.  That made it much easier (and quicker) to return the correct strip to its respective location.  That really paid off when I had to remove/replace the coroplast on the second occasion.  I also painted the strips black with some Rust-Oleum paint.

I replaced all my screws with a stainless steel version, because the head on a few screws had broken off, which has been reported by more than one T@B owner over time.  The heads most likely broke off due to over-torquing at the factory, corrosion, or metal fatigue. 

The screws are #10 x 3/4" self-tapping (use stainless steel) with a 5/16" head:



This is a sample of a section of the termination strip (photo by @Tabaz):

@spfrancis65 , did you read through the discussions I provided links for?

It is highly likely that you will not need to remove the coroplast.

You first need to do some troubleshooting to determine the likely location of the cause/source of the water leak. For example, is is from the fresh water inlet (where a hose from a campground/your residence connects to the trailer to supply water on demand), or is it possibly leaking from a hose connected to the water pump, or water line leading to the fresh water holding tank (which supplies water when you use the 12V water pump)? They are separate (but interconnected) means of supplying water via your water lines (to sink, shower, toilet) and Alde hot water tank. The issue may be as simple as hand-tightening a screw nut on the water line connection. OR, it could be a pipe clamp (e.g., PEX water pipe clamp, which requires a special tool).

WHERE TO START: The leak source may be reachable through the compartment door behind the toilet, where the water pump is located. It is not easy working in that area, so it takes a nimble person. There are other discussions on this forum about that. It is not easy to explain (simply) in writing how to do the troubleshooting, because we do not yet have enough information about the likely source of the leak. It is just guesswork based on experience at this point. Using a flashlight and small mirror will assist you in seeing inside that compartment, but even then it is difficult to see all the water line connections. The photo posted by @pthomas745 is a good representation of what is inside that compartment, but it is only a guide to how the connections are configured. The large black item at the bottom is the gray water holding tank. The black water holding tank (small) is above that (hidden), but is actually located above the interior floor, beneath the toilet. (IMPORTANT NOTE: The reason I indicated that you likely will not need to remove the coroplast cover to locate the leak is because removing the cover will not provide you access to the plumbing in the photo posted by @pthomas745. That is because the holding tanks will prevent you from seeing/accessing the plumbing. The only way to get to that plumbing, without removing those tanks, which you don't want/need to do, is through the compartment behind the toilet).

Regardless of the above, if you do ultimately decide that you need to remove the coroplast, you will not need to remove the propane tank tub. It is not involved in removing/reattaching the coroplast.

The coroplast can be removed by simply getting under the trailer and removing the screws. It just takes a bit of time and a lot of maneuvering around on your back. My 320S is a Boondock model, so a bit easier. I have never had to crawl under a standard 320S, so I cannot specifically comment on how easy it is to move around under it.

IF the coroplast does need to be removed to make repairs, although you might be able to get by with just removing the screws at the front end and lowering that part of the coroplast, it may be necessary to remove the entire coroplast cover, simply because it is fairly stiff and you would not be able to fold/bend it out of the way to get to the area(s) you need to work.

The blue pipe is 1/2" PEX for the cold water lines; red is for hot water. BUT, again, you don't need to worry about that for now, and it is very likely that you will not need to replace any of the PEX. You could very well just have a loose connection. Until you determine where the leak is, you can't determine what, if any, parts you may need.

Others can chime in with their thoughts, but it may be best to seek assistance or advice from someone that is handy with troubleshooting leaks, or possibly an RV repair shop, if necessary. Dealing with stuff like this often takes a bit of research and reading to obtain a full understanding of how the T@B systems work. You can learn a lot in that regard through posts on this forum, but it takes a lot of searching and reading. However, if you feel it is above your pay grade, as we all often find certain repairs can be, it is best to seek assistance from someone who is adept at resolving situations like you are dealing with.

BUT, first, do read through those discussions I posted so you can obtain a general understanding of how to troubleshoot the leak.

Best of luck to you.