Most times, the water pipes in your home will do their work without making any noise. Even if the pipes vibrate slightly as water flows through them, the sounds they make are often not loud enough to be heard. But sometimes, your water pipes will make clanging or knocking sounds that are both abnormal and annoying.
Why do the water pipes in a house knock?
McCourt Real Estate Management says there are several reasons why the pipes in your home might sound like a mischievous ghost is playing with them. But thankfully, all of those reasons are due to everyday plumbing issues that can be resolved fairly quickly. Below you will find six reasons why water pipes knock and what to do about the problem.
6 reasons why your water pipes knock and how to solve them
Loose pipes fittings
This is the most common reason why pipes knock and also the one that is easiest to fix. The pipes in your home, especially pipes that carry hot water, can detach from their holding straps. When this happens, the pressure of the water traveling through the pipes can cause them to move and knock against a wall or other pipes in their vicinity. To solve this problem, simply attach the pipes to a nearby stable object like a beam or support it with insulated pipe clips. If the pipe is inside a wall where you cannot reach it, pack the space around its exit and entry points with foam or a soft pad.
Air inside the pipes
Pipes will also knock if there are pockets of air locked inside them. Due to variations in the water pressure, the air inside these pipes will cause them to shake and clang. To solve this problem, turn off the water supply to your home from the mains. Open all the faucets in the house, including external faucets and water hoses. Leave them open until all the water in them drains out. After the trickle of water stops completely, close all the faucets and hoses, and turn the water on slowly. That should get rid of any air inside the pipes.
Pipes knocking against the masonry
Pipes will knock if they are too close to the masonry. That can happen even if the pipe fittings are in place. To solve this problem, here is what you should do. Wedge a piece of hardwood between the pipe and masonry. The wood should fit tightly to keep it from falling. You can ensure this by bolting the pipe to the wood with a u-strap. Another way to solve the problem is to encase the pipe with rubber or cotton batting to muffle the knocking sounds. You can also slit a piece of hose and use it to wrap the pipe.
Water hammers
A water hammer is a loud hammering noise caused by a sudden change in the direction or rate of flow of water. Water hammering mostly happens when the water supply is shut off suddenly, such as when a toilet valve is turned off swiftly. The solenoid switches in your dishwasher, washing machines, and ice maker can also cause water hammers when they turn off the water suddenly instead of gradually. You can solve this problem by installing a water hammer arrestor in your home. But since this is a more complicated issue than the ones mentioned above, it is a good idea to talk to your plumber.
Copper pipes
As a rule, hot water pipes are more likely to knock than cold water pipes. But metal pipes are also more inclined to knock. The knocking tendency of copper pipes increases when hot water passes through them. The heat causes the pipes to expand and rub against anything near them. One way to solve this problem or reduce its severity is to lower the temperature setting on your water heater. It will keep the pipes from heating up and expanding too much. However, if this is not an acceptable solution, your next option is to talk to your plumber about the issue.
Sediment buildup inside the water heater
This is the most unexpected cause of knocking pipes. This type of knocking can happen when water is not even running in the pipes; typically in the morning or evening. The culprit here is sediment that has built up inside your water heater. Steam bubbles that are trapped under this sediment will force your plumbing to make a knocking sound as they escape. The simple way to get rid of the problem is to flush the water heater. Water heaters should be flushed once or twice a year.
Getting the pipes in your home to stop knocking is easy if you can identify the origin of the problem. But if after doing the steps above, the problem persists, there may be a deeper issue with your home’s plumbing. In that case, your next best step is to get a professional plumber to do a thorough camera inspection of your plumbing system.