We have just finished a remodel on our rental house and recently had water turned on to check for leaks. After about a week, we noticed water coming from underneath baseboard into our bedroom. The bathroom sink is directly behind the wall from which the leak is appearing. Nothing is wet under bathroom sink, all pipes seem to be dry also, I also removed the access panel to check for leaks that might be coming from bathtub and maybe running down, it too was completely dry. I am attempting to dry the leak in bedroom with fan and will lay paper towels under the sink to see if I can discover a leak that way, other than that any suggestions? I want to have carpet installed in bedroom but I have to stop this leak first!

Did you work on plumbing for the sink during the remodel ? If positive, what exactly did you do ? Are you on slab or raised foundation ?

Yes, indeed, you should not lay carpet over wet floor. First, locate and repair the leak

In the interim...

The leak is obviously not from the inside of the cabinet. It is coming from the inside of the wall. It can be any pipe joint that leaks or carpenter shot a nail through baseboard right to the pipe.

If it is pressure leak ( hot or cold water pipe ), water should be coming out steadily . If it is drain leak, water will be appearing only when sink is in use.

If it leaks from the sink plumbing than - unfortunately, you will have to cut the wall to see what's going on. Wall can be cut for the bedroom side. Cut opening large enough so you can repair the leak.

If you have copper plumbing, you should be able to hear the leak. Wait until noise pollution is down for the day, put your ear on the wall behind the sink and listen for hissing sound.

If you have ABS /PVC drains, chances are plumber forgot to glue a joint or also, there could be a nail in the pipe.

Investigate and come back to let us know what you have found out. Back to you... Milo

We put in new cabinet, sink, fixtures, and plumbing which is coming directly up from floor into sink cabinet (no pipes are in the wall for the sink), tub-yes, pipes are in the wall. Plumbing is all pvc, no copper. That's why I decided to check and everything in the access is completely dry, no sign of any wetness. I have crawled under crawl space and checked and everything under the house is dry. This is really puzzling. We had the water turned on for about 3 weeks, no one has been in the house, so the sink has not been used, we just went into house the other day to prepare for carpet guy and noticed the leak.

If all the piping is coming up through the floor, including the drain, perhaps the water is not coming from the plumbing. If the drain is coming up from the floor and there is no pipes in the wall, where is your sink vent?

How about A/C condensation line ? Was there any before ? Did the plumber forgot to re-connect it into sink drain ?

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Originally Posted by hkstroud

If all the piping is coming up through the floor, including the drain, perhaps the water is not coming from the plumbing. If the drain is coming up from the floor and there is no pipes in the wall, where is your sink vent?

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The vent is in the wall. I wrapped paper towels around hot/cold water lines, and drain pipes yesterday. This morning I checked and both hot/cold water lines were dry, however, the paper towel I had around the pipe that is connected to sink and drain was wet, not soaking wet, but wet. So, I definitely have a small leak there (I tightened it up this morning) Being that the leak was small, would it be enough to run under cabinet and into the bedroom? Why is the cabinet bottom not wet? You got me thinking about the vent, we have been getting a lot of rain lately, in fact, we got a heavy rain over night, but the water stain in bedroom does not appear to be effected by that rain. Have been drying it with fan for past 2 days and it isn't 100% dry yet, but haven't noticed any additional wetness!

Show us a picture of the pipes under your sink.