What could be causing a wet floor, if a plumber finds no leaks?

On a day when you’ll be home dry everything under the sink to include drain pipes, the area where the sink basket attaches to the sink, valves, etc. Place a double layer of paper towels under everything and leave it alone. Check the paper towels every hour or so for dampness, which will show up prominently. When you see a wet spot look straight up and you should find your leak. You can also consider hiring another plumber to check it.

Paper towels on the floor and elsewhere (pipe connections, etc.) is how I look for leaks.

Good suggestion from Zard, another place to look is under the faucets under the sink, the connection there maybe loose. Or maybe the hoses are about to burst from the pipe to the faucet. Best to you...let us know what you find out.

Hi! I had that problem (with clean water)... it was the shut off valve!

Maybe this will help: https://www.youtube.com/watch?v=ycUsxmcsczU

We had an issue once where it was the connection (or valve) of the dishwasher which was leaking under our sink and then leaking under the floor cracking all kitchen tile grout. It got to the point there was water in our basement under that area. It was a slow leak which was hard to detect. May want to check that as well. Check any appliance that uses the water line.

We had a problem under our kitchen sink. Turned out our water filter had sprung a leak. Easy fix just replaced it.

Hi there,

Could be appliance cable leak(Crack) in connecting cable when in use (or from under pressure) when not in use, or coming up from under floor! Does the water smell or coloured in some way?........

Ken Erickson has the proper detection method. Make sure the area is dry, put down the paper towels, then check in 5 minutes. Do not go away for a few hours as you said but check it every 5 minutes. Set a timer and keep checking every 5 minutes until the edge of the paper towel is wet. Once it is wet start looking in that direction.

Please add the results to this question and someone will have another suggestion.

Hello again Brian,

Sounds as though one of the water supply pipes to an appliance has a split in it. Wrap a cloth or tissue around each pipe you have underneath the area. The check it very often, and that should tell you where the problem is! If no wet cloth or paper, then it must be coming up from the floor! Good luck!

We had a problem with the seal under our drain that went to our disposal wasn't sealing properly. Once it was removed and new plumbers putty put down, we haven't had any issues with leaks since.

Check your cut off valves to make sure they are not leaking. We just replaced one for the same exact situation.

years ago had a similar problem, water but nothing leaking...

Turned out it was a pinhole in the copper supply line in the wall.

One option would be to have another plumber come in for a bathroom inspection. Perhaps the one you called for the inspection is not sufficiently graded or has no experience with this particular problem. You can try to find the leak yourself. To do this, use dry paper towels. Wrap them around the suspected leak and wait. After a certain time, use the elimination method to find the leak. You will most likely need to replace the part to fix the problem. Doing any lining on the breakthrough will not have a long-term effect. If you want to learn more about plumbing or become a plumber yourself, I recommend going to https://www.howtobecomeaplumber.org/license/. There you can learn about how plumbers are educated, sign up for training, or find out any information in this area.

I remember when I had a similar issue a while back. We were convinced it was a leak too, but the plumber found nothing. After some research and a lot of trial and error, it turned out that the condensation from the pipes was causing the dampness. Crazy, right? So even though it seemed like a leak, it was actually just good ol' science doing its thing.

It may not be a plumbing problem per se, but a condensation problem. The cold water pipes running under the sink were causing moisture to condense on the pipes, and that moisture was dripping onto the floor. A plumber I know suggested using insulation or foam around the pipes to prevent temperature differences causing condensation. I can totally understand your frustration – plumbing mysteries can be so puzzling! I came across a helpful link that might shed some light on your situation nycplumbersdrain.com. They have some tips and tricks that could help you out. And maybe give this condensation idea a shot? I'm no expert, but sometimes thinking outside the box can lead to unexpected solutions.