Water hammer

'What is water hammer?'

[via Famous Plumbing Supply] Water hammer occurs a lot! It is frequently recognized by a 'thump' or 'bang', usually throughout the water line (if you have copper pipes, you'll tend to hear the noise throughout the house). Water hammer can be caused by a number of things. Many times a loose washer that is jumping around in the faucet or valve causes it. This can be fixed by identifying which valve is the culprit and fixing the washer. Other times it is simply caused by water traveling at a rapid rate and suddenly being shut off. The best solution for this is to increase the size of the water supply thereby slowing down the water (a larger pipe being able to deliver the same amount of water in gallons per minute at a slower speed). If this is not possible, then many times a water hammer arrester helps.

Sometimes the cause is excessive pressure and the best way to deal with that is to install a pressure regulator. In any case, please be aware that sometimes water hammer arresters will not solve your water hammer problem."