Whenever you have low water pressure in a single room, such as the bathroom, you need a simple diagnostic strategy to pinpoint the problem because there isn’t always a simple explanation. In some cases, you’ll be able to narrow the problem to a single faucet or fixture, but in others, you may end up having to inspect the hot water heater. If you have a leak, it probably won’t be hard to find.
Pinpointing the Problem
If only one fixture or faucet in the bathroom has low pressure, you shouldn’t have to look farther than the fixture itself for the problem. There is probably a blockage in the valve or aerator or a misadjustment of a temperature limiter. If more than one fixture is affected, you may also find low pressure in other rooms in the house because the cause is likely a partially closed valve or a blockage in a main supply pipe. If there’s a leak, it can affect a single fixture as easily as it can affect many. Leaks usually make themselves known by pooling water or soaked drywall.
Loss of Pressure at a Single Fixture
When the pressure at a single fixture is lower than expected, it could be because mineral deposits have blocked the valve or the aerator. It’s easy to check the aerator — just unscrew it and look inside it. If you see white deposits, either flush them out with water or soak the aerator in white vinegar to dissolve them. White vinegar is also effective for dissolving deposits from the valve mechanism. Sometimes, the pressure is low because the temperature limiter isn’t adjusted properly. The limiter is a plastic washer that you can adjust by hand after removing the faucet handle.
Loss of Pressure in the Entire Bathroom
Low water pressure in the entire bathroom signifies a blockage or leak in the main pipe that supplies water to it, and the problem may also affect fixtures in other rooms. A blockage may be something as simple as valve that someone partially closed — perhaps to make a repair — and forget to reopen. Blockages also happen around old water heaters as rust and minerals clog the hot water output. You can usually flush these after turning off the heater and allowing the water to cool. Air in the pipes can also cause a blockage. You can often purge air by opening all the faucets in the house at once while you flush the toilets at the same time.
Dealing With a Leak
The worst-case scenario is that the loss of water is the result of a leak, and if that’s the case, it’s probably a fairly large one, which should make it easy to spot. If your pipes are leaking, it’s important to turn off the water as quickly as possible because water can quickly damage your framing, walls and floors. You may then have to remove some drywall to get to the problem pipes. Once they are accessible, you can often fix the leak by installing a compression coupling, which doesn’t require solder. You’ll probably need a plumber, however, to fix a leak from an elbow or a complex fitting, such as the shower valve.