Water Under Bathroom Sink (No Leaks Found)

[rayman]

I have a 2021 E Pro 19FD and I found water under the bathroom sink a couple of mornings ago. Cleaned it up, opened up the panel to get access to the pipes running in the chase under the sink. Could find no leaks. Placed paper towels under the lines to see if I could locate a leak. Nothing seen after 12 hours. (paper dry) Woke up this AM and paper was soaked, pipes were dry. Cleaned up and put more towels down. Ran water, took 2 showers to see if water was coming in from shower. (Although I would wonder who might have taken a shower in the middle of the night). Still dry, ran Black Water take back flush, still dry pipes dry.

It was cool ( 48 degrees) last night and the heat was running and the pipes are resting against back wall (condensation???) Not sure but I am baffled. Anyone have any ideas about how the water is getting there?

[bobbecky]

If you have a black tank flush system installed, you will probably have an air gap/back flow valve installed up high under the sink, and with that there will be an additional two lines going to that valve. Hopefully you do not leave a hose connected to the outside hose fitting that connects to the black tank flush. If you do have a hose connected, remove it when not flushing the black tank because that valve under the sink could leak if it constantly has water in it, and removing the hose will allow water to drain from your flush system.

[bsmith0404]

Check the water connections to the faucet. Sometimes they have a slow leak that just drips from time to time, doesn’t always get the lines wet, just a drip from the nut. It’s not always enough to notice a drip, but when left for several hours can soak a paper towel. Also check your drain connections at the p trap if you have one, but is suspect it’s the water lines. I’ve tightened them up on several RVs and the symptoms were very similar to yours

[LHaven]

Sometimes you can speed up the diagnosis by wrapping individual paper towels around each plumbing line, with masking tape. They don't have to be big.

[mbi777]

I’ve got the same problem. Will have to try wrapping each connection with paper towel and masking tape as someone suggested

[Berdan]

On my 22RBIWE the black tank flush connection pipe goes under the bathroom sink. I found water under the sink and traced it back up the hose to the flush connection. It turned out the caulk around the outside of the connection had deteriorated and when it rained some of the moisture would get in the edge of the connection and follow the pipe down to under the sink and drip at the low point. Re-caulked the edge of the connection and had no problem after that.