Ah, the mystery of dripping, invisible water. You’ve asked an interesting question and we see that you’ve taken the time to look around and see if there was water damage to the home. Since you have found no evidence of actual damage, the next step is trying to isolate the problem.
Have you tried investigating each fixture separately? We would suggest starting with the sink, then trying to hear whether you hear the leaking. Next try that with the tub. Finally, we’d suggest seeing if the dripping also occurs when you flush the toilet.
If it happens with all three, there may be a bend in the drainage pipe from your bathroom and the leftover water in the piping ends up at that spot dripping within the pipe. At least, from hundreds of miles away and without our X-ray vision, we can only assume that to be the case.
As you test the fixtures in the bathroom, think about where exactly you hear the dripping. If you are able to isolate a spot where the sound is the loudest, try to imagine if the contours of the home (behind the walls) are such that you could visualize a bend in the drainage pipe in that area.
Since many newer homes use PVC plastic piping for waste water, dripping water tends to echo within the plastic pipe. In older homes with cast iron waste pipes, the pipe can contain the sound of the water better.
We certainly hope your issue is water dripping within the pipe. If not, you can also check for leaking water without opening up the walls using two types of instruments used by the professional home inspectors to check for water problems.
One of these devices is a moisture reader. When you place the instrument on a wall it measures the moisture content in the walls. If you have a slow leak that is not visible but may be causing a moisture problem behind the wall, the moisture reader might pick it up.
The second instrument many home inspectors use are infrared cameras. These cameras can pick up variations in temperature. Frequently water or moisture will create hot or cold zones in a wall.
If you can borrow these instruments from a contractor friend, you can give it a try. Or, you might be able to rent them at your local home improvement store. Otherwise, you can call a plumber or home inspector to come over and go over the area. (You might want to call a plumber anyway. When we asked our plumber, he told us that he has seen strange expansion and contraction issues with the piping in some homes that sounds exactly like water running when no water is on in the house.)
If you love gadgets, you might even pick up a used or new one of these devices online or from big box retailers. We don’t know how much use you’d get out of them in the future, but they do reveal problems that you otherwise can’t see with the naked eye. Good luck.
Ilyce Glink is the creator of an 18-part webinar + ebook series called “The Intentional Investor: How to be wildly successful in real estate” as well as the author of many books on real estate. She also hosts the “Real Estate Minute” on her YouTube channel. Samuel J. Tamkin is a Chicago-based real estate attorney. Contact them at ThinkGlink.com.