Kaboom! Why are your water pipes banging?
Q: Every time I shutoff a faucet inmy home, my water pipes rattle and make a dreadful sound. It seems tome that they might burst. Theproblem iscommoninmany houses onmy street, as I’ve askedmy neighbors if theyhave the sameproblem. What’s happening? Did the builder or plumbermake a mistakewheninstalling the pipes? Is there a danger of pipes bursting and flooding? Is there an easyfix, evenDIY? Help before I need a life jacket!
A: I used to hear loud crashing noises caused bywater hammer at one of the first homes I lived in when Iwas inmy early 20s. At the time I didn’t think much of it and had yet to sit formy master plumber exam. I lived in an area where the citywater main pressurewas close to 80 pounds per square inch. The highwater pressure waswonderful for showers and garden hoses, but the noisewas a nuisance, especially when the electronicwashing machine and dishwasher valves shut off.
If you dust offyour high school physics textbook, you’ll discoverwhy the water hammer is happening. First, water is a liquid, and most liquids are not compressible. Water is also pretty heavy. Stop for amoment and think of the velocity ofwater as it rushes out the end of your garden hose. That’s how fast, for the most part, the water ismoving through yourwater lines.
Imagine if thatwater in the pipes insteadwas a tiny freight train chugging along. All of a sudden, right in front of the locomotive, a valve shuts off. The train crashes into the valve and the energy sends a huge
pulsewave through the piping. The pressure within the system can spike towell over 180 PSI. You bet that can cause problems over time. Acatastrophic leak is absolutely possible from countless shockwaves.
The plumberwho installed your piping could have prevented the water hammer by installing larger-diameter pipes within the system. Larger pipes, by their very nature,
slowthe velocity of the watermoving through the pipes. All theywould have had to dowas extend
-inchwater lines to each fixture group and to critical fixtures likewashing machines and dishwashers. These machines have electronic valves that slam shut whenno morewater is required.
Cross-linked polyethylene, orPEX, plumbing supply lines also could have
helped. These flexible, innovative plumbingwater supply lines install much like electric cable and they can jiggle andmove around to absorb the shockwave that pulses like a bomb going off in yourwater lines. Copper is rigid and it can bang and shudder, as youwell know.
The good news is there areways you can pretty much stop thewater hammer within your home.
If you possess moderate plumbing skills, it’s absolutely a DIY opportunity to get out your soldering torch and other tools.
I’d install two things to start: a spring-activated pressure-reducing valve and one or twocommon expansion tanks. Both of these affordable accessories do amagnificent job of taming the wild stallions that are galloping through yourwater lines.
The pressure-reducing valve can be adjusted by turning a screw. Be sure you pay attention to the direction of thewater flow on the body of the valve. Most of the time, this is installed just past the main shutoff valve for your home. While you have the water off, install a secondary main shutoff ball valve in case you have awretched old gate valve. Ball valves allowfor full flow, and they’re usually trouble-free for decades.
Just after thisnewball valve, consider installing a tee fitting that will allow you to put in a boiler drain so you can easily drain out all thewater in your water lines. Many plumbers fail to install this simple accessory. I’d also install a second tee fitting in the mainwater line. This will allowyou to install awater pressure gauge. You’ll never regret having one of these, trustme.
After you install all that, consider installing a 3-gallon expansion tank. These arewonderful devices that have a rubber bladder within the tank. The bladder separates the water in the system from a bubble of air inside the tank. Be sure to install this tank so the threaded inlet points down toward the floor. This allows the air bubble to be above the water, not belowit.
The air bubble acts just like a shock absorber in your car or truck because air is compressible. These expansion tanks also do double duty protecting your storagewater heater as heatedwater also needs a place to expand.
I knowthis seems like a lot of plumbingwork, but it’s not. You can do all of this in an hour or less if you knowwhat you’re doing. Just followthe plumbing code and best practices, and soon your home will be as quiet as a lamb.