While mowing the lawn, I noticed moisture at the base of the exterior wall. I stopped the lawn mower, inspected the moisture, and thought perhaps it was due to the rain.
The following day, the moisture was still there. Rain was scratched off my list of possible reasons for the moisture. The only logical reason would be that there was a leak behind the wall; perhaps, the leak was coming from my son's bathroom.
To test my hypothesis, I waited for the moisture to dry. The weekend was the best time to test the hypothesis, since my son takes showers on school days.
Sure enough, after he took his shower, the moisture reappeared.
I went inside the house to check the walls, the ceiling, and floor for any wet stains, but couldn't find any signs of damage.
I feared the worse. This could have been going on for months or even years. Maybe there was mold behind the walls. Perhaps there is a lot of water damage. "This is going to hurt financially," I thought.
I emailed my insurance agent to ask whether my policy covered water damage. He indicated that the particular policy that I purchased did not cover water damage. He suggested that I find a plumber to find the leak.
I contacted my neighbor who happens to be a licensed plumber. He helped me in the past when I accidentally disconnected my neighbor's water supply and when I managed to flood my backyard.
He thought perhaps the leak was caused by the diverter, which had built calcium deposits that prevented it from working properly. He changed it out and put a new line of caulking.
The following day, after the caulking dried, I tried the shower and again noticed the leak at the base of the exterior wall.
My plumber returned and decided that perhaps it was the drain pipe. After cutting three holes, we finally found the culprit. A nail had penetrated through the exterior wall--perhaps caused when the builders nailed the sheathing before laying the bricks.
The leak was caused when the nail eventually rusted and fell off.
The plumber fixed the pipe by cutting the section of the damaged PVC pipe and replaced it with a new PVC section using couplings. The pipe was fixed and working.