The Mystery Leak

One afternoon some years ago, I walked into the dining room on the first floor of our house and turned on the light. It seemed unusually dim. I looked closely at the spherical-glass ceiling fixture and was shocked to see that it was half full of water. This situation was not good.

I’d recently installed a bathroom on the second floor, and it was directly above the light. This was the bathroom five of us had lived without for 20 years. Now that our three kids were gone, my wife and I decided that we really needed this second bathroom. After months of labor, we had it. Or did we?

As a reluctant plumber, I hadn’t been excited about tackling this job. How could I repair the leak without ripping up the new bathroom floor? Then I remembered that I had taken pictures of the plumbing before I installed the floor that covered it up. Because I had discovered that the leak stopped when the hot water was turned off, I could narrow my search to the hot-water supply line.

I’d built a small closet next to the shower enclosure as an afterthought. While nailing the bottom plate of a section of the wall to the floor, I realized that a copper pipe might be in that immediate area. As a result—and as the photos confirmed—the last nail was not driven all the way in. That was the area I needed to investigate.

After making a small opening in the wall near the partially driven nail, I discovered that the point of that nail had penetrated an elbow fitting on the pipe. Water was dripping from it.

Why hadn’t the leak appeared until a month after the completion of the project? Initially, the nail point was touching the fitting but not penetrating it. As hot water flowed through the pipe, the pipe expanded and pressed on the nail a little bit every day until it punched through.

My insecurity as a plumber was what led me to take photos of my project as I worked on it. In this instance, that was a good thing.

I drained the system and soldered the hole. It did not leak again during the years that we lived in the house.

I still avoid any work that involves plumbing.