How To Fix Water Hammer Problems In Your Plumbing, According To An Expert

Have you ever noticed that shocking knock or bang after you turn the water off in your bathroom? It's a phenomenon known as a water hammer. "A water hammer is a knocking noise that happens when a water supply valve is shut too abruptly. Some valves are designed to close fast, like that of a washing machine. However, a water hammer can occur even from shutting a faucet too quickly," explains Jake Romano, manager of John The Plumber.  

In an exclusive interview with House Digest, Romano went on to say "water hammers occur because of the pressure from fast-moving water being forced to stop quickly. This results in the water slamming into a barrier, which creates a loud knocking sound that can be startling." While this sounds fairly benign, it can actually wreak havoc on your plumbing system, says DFT Valves, causing pipes to withstand extreme and sudden pressure changes. Romano has some more useful advice to help understand what causes a water hammer to occur, and how to best solve it. 

While that thumping sound you hear when you turn off your faucet may not cause immediate alarm, water hammers are very serious, and can cause severe damage to your pipe system if left untreated. It's easy to feel like you only need to call the plumber when you can actually see a problem, like pooled water on the floor. However, Romano tells us, "It's important to remember that a water hammer isn't just a loud, surprising noise — it's your water supply system being violently jerked this or that way. And that's obviously no good." 

He goes on to say, "A water hammer is caused by a shockwave from fast-moving water coming to a stop. When the water slams into a valve, the momentum shakes the whole pipe and joints, and perhaps your whole system." Romano then warns that "water hammers can loosen or break pipe hangers, weaken the joints and connections, and cause serious leaks in your home."  So if you hear that knocking, it's important to treat the problem sooner rather than later, because ignoring it will lead to greater repair costs and damage over time.

Taking on your own plumbing system can be a bit intimidating, but thankfully there's a soldering-free method for getting rid of water hammers that even the somewhat inexperienced can handle. You can install what is known as a water arrestor — an easy-to-install solution. A water arrestor is a copper device you install on the supply lines of water-using appliances that can sense surges of pressure and briefly opens and closes the valves, which causes the pressure to equalize, says Ezy-Plumb. Romano instructs, "Purchase the appropriate water hammer arrestor and install it on the water shutoff valve that supplies water for the water hammer-prompting plumbing fixture." 

But be warned that this may not be a one-stop solution, particularly if you have water hammers throughout your home. "But it's not a bad place to start if you're comfortable working with plumbing," Romano offers. If you're breaking a sweat at the idea of looking at your own pipes, it's best to call in an expert and go over the best options for your house. 

While you're researching what to do with your water hammer, beware of outdated solutions. In particular, Romano warns of the capped water line method. "Plumbers would install a capped water line near the plumbing fixture that prompts the water hammer. The capped line would be connected from the bottom to ensure that air remained as trapped in the capped pipe as possible," Romano explains. 

"But the issue is that as water hammers, it pushes water into the empty pipe and slowly replaces the air. Within a couple of weeks, most or all of the air in the capped line has been replaced by water, which doesn't do anything to help the loud banging noises — rendering this solution useless," notes Romano. Temporary fixes only tend to prolong the problems and symptoms of chronic water hammers. So if your plumber suggests a capped water line as a solution to your water hammer, you should definitely look for another proposal, like water arrestors.

Even though that water hammer may seem like it's little more than a startling noise, it is essential that you take care of it proactively. And while there are some methods you can try yourself, sometimes you need a professional. "If you're dealing with a water hammer and the easy-to-install threaded water hammer arrestors don't solve your problem, which is often the case, the next move is to install a proper water hammer arrestor," Romano tells us. These differ from what is typically available to novice users, and requires additional skill and equipment to install. Romano adds, "You're going to need soldering skill. It's not the hardest thing, but it's hard enough that most homeowners prefer to call licensed plumbers."  

Even if you're willing to take a chance with a soldering iron and your own abilities, keep in mind that you may cause worse damage to the pipe system. This will result in more extensive, and expensive, repairs that you'll need a professional to solve. Romano warns, "If you make a mistake then you're going to deal with a big leak or flood — and that's not ideal." So, when in doubt, get the professional over for the more heavy-duty repairs.