Leak in the Ceiling Below a Bathroom

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Leaks may travel through the subfloor before dripping onto the ceiling below.
Image Credit: Andrew Bret Wallis/Photodisc/GettyImages

Leaks in the ceiling below a bathroom usually mean your toilet, sink or bathtub are leaking. Water leaks from a plumbing fixture or pipes may go unnoticed for days or even weeks, until you notice a wet spot or water stain on the ceiling below. It takes a little detective work to find the source of the leak to repair it. Once you see that the water is coming through the ceiling, take immediate action before the leak causes any more damage to your house.

Finding the Leak Location

Just because you find a leak in the ceiling below a bathroom doesn't mean you necessarily know the point of the leak's origin. Leaking water doesn't always fall straight down, but can instead run along pipes, floor joists or other surfaces before falling onto the ceiling below. Even if the leak appears below the sink, it could be coming from the toilet or tub. If the leak is below a different room, it could be traveling from the upstairs bathroom.

Start by looking in the bathroom is you suspect the leak is coming from there. You might be able to find the leak by looking at the fixtures in the bathroom. You can cut a hole in the ceiling and look around with a flashlight to positively identify the origin of the leaking water if you can't find it using other methods, or use plumbing access doors such as the one found on the wall behind some shower or bathtub faucets.

Identifying Toilet Leaks

If your toilet is the origin of the leak, you may see water pooling around the toilet, or the floor around the toilet will feel spongy. If the leak seems to be coming from the toilet's tank, drop food coloring in the tank's water and wait to see where the colored water exits the tank. Tighten loose parts, or replace those that leak even after you have tightened them.

The leak may be coming from a loose connection between the base of the toilet and the waste pipe in the floor. You must unseat the toilet, scrape off the old wax ring and inspect the floor flange for damage. You then need to replace the wax ring. Always seat your toilets so they don't rock in any direction; otherwise, the toilet could leak again in the future.

Identifying Sink Leaks

You'll see water damage or pooling water in the cabinet below the sink if the sink's drain or pipes are the origin of the leak in the ceiling below a bathroom. Tightening the retaining nut on the drain body or the connections between the pipes will eliminate some leaks at the joints. If your pipes don't have plumber's tape on the threads, the pipes may leak even though the connections are tight. If you find it difficult to tell the origin of a leak, dry off the pipes and use a tissue to determine if water comes out of a specific location.

Bathtub and Shower Leaks

If you suspect the shower or bathtub is the origin of the leak, use a bucket to determine if the water supply lines or drainpipes are the cause. By running the faucet but filling up a bucket instead of letting the water go down the drain, you will see if the leaking continues or stops. If the leaking continues, you know the water supply pipes are the cause.

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Steven Symes

Steven Symes has been writing for six years. His articles have appeared on a number of websites, including some regular columns. Symes has been writing professionally since 2005. He currently holds a Bachelor of Arts in English from Brigham Young University and is partway through an Master of Arts in English at Weber State University.