Fresh water tank leak mystery

[43D18]

I'm noticing a slow leak from the fresh water tank. This seems to manifest itself when the fresh water tank is full. There is no indication of a leak inside the fresh water tank compartment. I have inspected and felt around inside and detected no moisture at all. You can see from the photo that water is collecting along the lower steel frame member that supports the water tank. But I can't determine the source of the leak. Any ideas?

[cavie]

Tank overflow?? Do you have a hose hanging down for that?? Maybe a loose connection?

Fill the tank to capacity and see if it gets worse.

[bubbles]

What you see is the tank vent (overflow) tank drain and low point drain.

[43D18]

Correct - you are seeing the overflow tube, and it works as advertised. In fact, I have an unrelated issue - I'm guessing the check valve in the water pump is not working correctly, as my freshwater tank sometimes fills when hooked up to city water causing water to run out of overflow tube. This problem has been documented elsewhere on this forum.

But back to this water leak, I'm unclear how to determine the source of this leak.

[TitanMike]

Originally Posted by 43D18

But back to this water leak, I'm unclear how to determine the source of this leak.

Check the obvious first. Make sure the vent hose is connected properly to the tank on one end and usually the fill port on the other end.

Another possibility is a loose connection on the fill hose where it meets the tank.

Depending on how well covered your tank is, you may have to remove some panels. Another possibility is to use a flexible inspection "Scope" like those that are used to look inside walls by inspectors/contractors. You can often rent one. Fill the tank as full as you can and look into every space around the tank you can, paying close attention to any area where there is a connection. Just HOPE you don't have a hole in the tank caused by an errant drywall/sheet metal screw.

If I were a betting man I'd bet on one of the connections at the fill/vent area.

[Tomgky]

I had the same problem and found it to be a hairline crack in one of the corners of the tank. It only showed up when the tank was full. The tank expands a bit when full causing the crack to open. I bought a patch kit from a RV dealer and patched it while empty. Won't know if it worked until spring. The trailer was already winter ready when I did the patch. It seemed to work well. It was a two part epoxy with fiberglass mesh.

[James Storm]

Use a green or blue food coloring and fill your tank. It should leave a stain mark at the leak spot. Red is not a good color to use because the antifreeze you use is red and someone might mistake it for that.