Water pump

[Guitarman3]

Wonder if anybody can help, in my Motorhome, under my bed , I have a big water tank ... I noticed when the water is at a certain level, there is some sort of leak, and my carpets get mouldy and damp... I could not find anything wrong with the tank, so, because I didn’t know what to do, I just never used it again, so, I could never wash dishes, or use taps at all...
has anybody any idea how I can approach this? I’m assuming it’s the water pump, or some sort of seal, but, I can not seem to access/see anything.
Thanks in advance for any help.

[arcaguy]

You don't say what this "certain level" is but I assume you know. Since water doesn't flow uphill whatever the issue is exists below that level. The first thing I would check is the fittings around that level, if there are any. I might take a while but get everything dry and fill the tank to the level that creates the leak then watch for a few hours to see where the water first appears, the leak will be in that area. Fittings, especially plastic ones are high on the list of suspects. Another method is to put some air pressure in the tank and listen/feel for air leaking out. These processes are fairly simple but can be tedious and time consuming. Good luck.

[HarryStone]

If you can, some blue or red food dye in the water will help identify where the leak is coming from. The water pump is out of the equation, because it always pumps water, regardless of the level in the tank, until it's empty, of course. So, I'd be looking for a crack (very hard to see) or a loose connection for the overflow hose or fill hose, or a cracked or broken hose.

Edit: BTW, if you are at a camp site, the water inlet for your MH 'should not' fill the tank, and you could use a hose to provide pressure to your taps.

[Gary RVRoamer]

One thing I would check is the air vent for the tank, which often doubles as an overflow port. It will be at or near the top and thus would leak only when full or nearly so. The vent hose may have been disconnected or the fitting may leak.

[Guitarman3]

Originally Posted by Gary RVRoamer

One thing I would check is the air vent for the tank, which often doubles as an overflow port. It will be at or near the top and thus would leak only when full or nearly so. The vent hose may have been disconnected or the fitting may leak.

I never thought of that, I’ll check this...

[Guitarman3]

Originally Posted by HarryStone

If you can, some blue or red food dye in the water will help identify where the leak is coming from. The water pump is out of the equation, because it always pumps water, regardless of the level in the tank, until it's empty, of course. So, I'd be looking for a crack (very hard to see) or a loose connection for the overflow hose or fill hose, or a cracked or broken hose.

Edit: BTW, if you are at a camp site, the water inlet for your MH 'should not' fill the tank, and you could use a hose to provide pressure to your taps.

Harry I’m off grid, where will the overflow hose be? If I send you photos would that help? I know the water pump works because I can hear it..
Wish I could sort this out .. if I put dye in the water, what then am I looking for?

[Guitarman3]

Originally Posted by arcaguy

You don't say what this "certain level" is but I assume you know. Since water doesn't flow uphill whatever the issue is exists below that level. The first thing I would check is the fittings around that level, if there are any. I might take a while but get everything dry and fill the tank to the level that creates the leak then watch for a few hours to see where the water first appears, the leak will be in that area. Fittings, especially plastic ones are high on the list of suspects. Another method is to put some air pressure in the tank and listen/feel for air leaking out. These processes are fairly simple but can be tedious and time consuming. Good luck.

Yes, I’m not sure what that level is , how will I ascertain that level? So, I can put air in the empty water tank and listen for a leak?

[Ljwt330]

Originally Posted by Guitarman3

Yes, I’m not sure what that level is , how will I ascertain that level? So, I can put air in the empty water tank and listen for a leak?

You cannot pressurize the tank with air unless you can access the overflow/vent and block it off, as well as any gravity fill port you may have. IMO, if you have access to the overflow/vent of the tank, you can troubleshoot by filling with water and observation, as mentioned by others.


Now, if you have a tube hanging down that connects to the overflow, that also serves as the vent, that can be blocked.

[rarebear.nm]

Overflow hoses may exit next to the gravity fill opening or may go straight down under the frame. Those that are go downward are more prone to getting mud or other debris blocking the water flow when the tank is full. Does it leak when parked or only while in motion?

The food coloring makes it much easier to see where a leak is coming from. Sometimes it is hard to see 360 around a fitting. So I may use a tissue that soaks up even tiny amounts of water very quickly. In this case I'd also run a tissue over as much of the tank's surface as I could reach. Again colored water will show very easily on a tissue.

It would good to know at what level the tank leaks. Frequently, water tanks have a bottom port for the pump and gravity drain (may be two ports as on my 5th wheeler or one as on my MH), a top port for gravity fill, usually like a 1 1/2" tube and maybe a fill for a city water connection. Many tanks have four more holes that the tank level sensors mount through, full, medium and low plus one for the ground wire sensor. Any of these may be leaking or perhaps a seam or any place else. Has the RV ever been exposed to freezing temperatures while there was water on board? Whereas, it's uncommon for freezing to damage a plastic tank it can very easily damage a fitting.

Is the wet carpet a small area or like the entire bedroom? If only a small area I'd be starting my search near that area.

Good luck...