Loud Pipes When Water Shuts Off

[greggor36]

Hello - Every time the toilet finishes running, the washing machine stops the rinse cycle or even the dishwasher stops the rinse cycle, the pipes make a loud bang. I'm guessing the water is being shut off from the toilet, washer, etc. It sounds to me like I may have too much water pressure but whenever I turn on the faucets or turn on the shower/tub the water doesn't come out abnormally strong like I would expect with a home that has a lot of water pressure.

Has anyone ever heard of this and if so, is there anything I can do about it? Should I be concerned about bursting a pipe, etc? Thank you for any help anyone can pass along.

 

[DonL]

Are you on a waterwell or is it city water ?


Good Luck on your project.

 

[Sponsor]

 

[greggor36]

I am on city water. Thanks for replying!

 

[DonL]

You should have a Pressure regulator on the city side, And a expansion tank on your water heater input.

The Tank could be water logged, Or the regulator could be bad.

I would check those things first.


Good Luck.

 

[greggor36]

Thank you! I appreciate the help! I will look into both! I was wondering if I needed a water hammer arrestor as well?

 

[DonL]

Thank you! I appreciate the help! I will look into both! I was wondering if I needed a water hammer arrestor as well?

You should not need them, if you have a working expansion tank, And your regulator is not set to high.

A hammer arrestor can give more places to leak.

Are you in a new home ? Has it always done what it is doing ?

 

[Reach4]

You need water hammer arrestors at the end of the pipes where water gets turned off quickly. The newer versions have a piston inside to separate air from water so that they don't get waterlogged. The older versions were just vertical pipes, maybe 20 inches long , and capped at the top. The air in the pipe would cushion the flowing water to prevent a bang. If you have the old type, you might be able to drain them by turning off your water and draining the water through your lowest faucets. This draining may or may not be effective.

For the washing machine, you may be able to add a pair water hammer arrestors easily.

 

[greggor36]

Thanks for the follow up! I am in a townhouse that was new when we bought it back in 1998. It seems to have always done it to some degree over the years but it just seems stronger lately. Would you recommend installing both the expansion tank and replacing my current pressure regulator? Should I install a gauge on each side of the pressure regulator for further monitoring or is that overkill? Hopefully my pipes don't start bursting like they show in the movies before I get this fixed!

 

[greggor36]

Would adding water arrestors, expansion tank and updated pressure regulator be too much? Would I end up reducing my water pressure too much?

 

[Reach4]

Arrestors do not decrease the water pressure.

You should get a pressure gauge with a peak recording (lazy hand). These are available with a garden hose thread (GHT) and should cost under $15. It can go onto an outside hose bib, a laundry faucet, a water heater drain valve, etc.

If you do have a pressure regulator already, and you have had a change in your conditions, there is a good chance that the expansion tank has failed. If you turn off your water and open a faucet to drop the water pressure to zero, the tank should not have water in it. When you knock on it, it should sound hollow. If it is full of water replace it. Replacing that tank is simpler than replacing a PRV. With your gauge, you should be able to diagnose things.

As a temporary substitute for the expansion tank, you can run a faucet at a medium drip or slow dribble. That will serve to relieve extra pressure, from the water heater heating water, that the working expansion tank would have taken care of. But that is just a temporary workaround. Get that gauge (or 2).

An expansion tank should have the air precharge set to the pressure that the PRV regulates to, or maybe a PSI or 2 more. Use tire gauge and tire pump to accomplish that.

 

[greggor36]

Thanks for the follow up. I currently don't have an expansion tank in place so I will install one. Thanks for the further clarification on the PRV too! You guys are the best! Thanks again!

 

[Reach4]

Thanks for the follow up. I currently don't have an expansion tank in place so I will install one.

NO -- I would not add an expansion tank to solve water hammer without taking readings unless you already have a PRV! Expansion tanks are not the cure for water hammer.

Get the gauge. Easy. Available locally. If your water pressure peaks above 80 PSI, then you can look into a tank.

 

[hj]

quote; Hopefully my pipes don't start bursting like they show in the movies

Do you REALLY think ANYTHING happens like they show in the movies?

 

[greggor36]

Thanks for clarifying! I will get the gauge and go from there. Thanks again!