There is water under my bathroom sink. About 1 1/2 cups. I can't find where the leak is coming from. None of the pipes or lines are wet. I have run the water for minutes and no drip. However after several days of the area being dry I will check it and there is the water again and lots of water 1 cup or more, and still NO wet pipes. After running the water again still no leaks or wetness on the pipes. This is my second bathroom and not used very often. It does but up with my master bath sink. I have run water in the master hoping to see a water trail between the wall pipe but nothing.

It can be any pipe under the sink - even cracked sink itself.

For now, do this: Lay down paper towels under the sink. In the morning, see where there is sign of wetness. Look directly up. Check the pipe directly above the wet spot.

I have done the paper towel thing 3 times and each day I look and the towel is dry then after several days I look and the entire 3 sheets of paper towel is soaked with water. I have looked underneath the sink and checked the pipes thinking with all this water I am sure to see a wet trail some where but NO everything is completely dry not even mositure. Because of how much water has dripped the entire paper towel is wet so I can't see the exact spot of the drip. It is the oddest thing. I have been dealing with this for 3 weeks. And like I said there will be days that go by and no wetness and then all this water will happen all of a sudden. It has been 7 days since the last water leak.

Water can be dripping from - let's say - nut on the trap. Once water drips out, and water level is lower than the point of the leak, water stops dripping and pipe dries out. So even it is dry - it doesn't mean it is not leaking.

Overflow of the sink?

Hi all:

Wrap some TOILET PAPER up around the piping near the sink. Then run the sink for a couple minutes. After that, you'll want to fill and drain the sink a few times all the while checking the pipes and the toilet paper. Fill to overflowing and then drain, etc. Have a flashlight handy and check all... a leak should show somewhere using this strategy... ;)

Once you think you've found the leak use the tissue paper to confirm each joint's dryness... toilet paper ALWAYS finds these buggers... :)

Back to you...

Mark

PS: Is this a sink associated with a CORIAN TOP? Let us know.