Need help with plumbing problem

I'm hearing a "thunk" sound when water is turned off. When toilet fills and shuts off, or washing machine shuts off, or shower there is a loud thunk. Any ideas ? Thanks
  8 answers
  • Kiff Harvey Kiff Harvey on Apr 28, 2014
    is the plumbing vented?
    • Mic M Mic M on Apr 30, 2014
      @Kiff Harvey Yes, it is vented, and only started a few months ago. Thank you for your help. Mic
  • Traci BlitzenBenish Traci BlitzenBenish on Apr 28, 2014
    Do you have well?
    • Mic M Mic M on Apr 30, 2014
      @Traci BlitzenBenish No Traci, no well. City water supply. Thanks for responding. Mic
  • sounds like you have air in the pipes. The question Traci asked is important because if you are on well water, your pump could be not working properly and air could be in the lines.
    • See 1 previous
    • @Mic M worth a shot...we had this problem many years ago when our shallow went went and we then had to drill a 500 foot well. Good luck1
  • Moxie Moxie on Apr 28, 2014
    I think you may have a loose pipe. When it kicks from the pressure change in the line it is moving and making a noise. A strap should hold the pipe in place. If this is the case over time a leak or broken pipe could occur from the movement. Let the sound be your guide as to where the problem could be. If it happens when you use all your water it would be somewhere close to the water line service entry, probably where it rises (and before branches off to other locations) Just a guess....good luck.. I had a similar problem but it was isolated to the shower...the line had come loose in the wall, we added a new bracket and problem was solved.
    • Mic M Mic M on Apr 30, 2014
      @Moxie Well, hubby will be "happy" to go under house to check lines. It does seem to be in one area where it is happening. Thanks, Mic
  • Lateral Concepts, LLC Lateral Concepts, LLC on Apr 28, 2014
    The first thing you need to do is determine what your incoming water pressure is. It should not exceed 75psi. If it's above that, a pressure regulator needs to be installed or replaced. A water pressure gauge can be purchased for just a few bucks at a hardware or bix box store. Check the pressure on one of the outside hose bibbs or buy an adapter to hook to your kitchen faucet.
  • Hamtil Construction LLC Hamtil Construction LLC on Apr 28, 2014
    The thunk is called "water hammer" and it happens frequently if the water supply pipes in each room (bathroom, kitchen) do not contain air chambers or shock arresters. They act like shock absorbers when the water forcefully shuts off. By code, we have to add these when we remodel. I added photos of some aftermarket "add on" type arresters. In addition, Lateral Concepts has a good point. Why did this suddenly start happening? A likely culprit is a failed pressure reducing valve (if you have one). Checking the water pressure with a $10 gauge is a good step to see what your pressure is. Try to adjust it. I suggest starting at a setting of 55-60psi and see if it serves your household needs. Above 75psi and you definitely need to turn it down. Try to adjust the pressure reducing valve if you have one. If is does not work, you need to replace it and it will help the pipes to stop banging. It's also possible that you have a pipe hanger which has come loose someplace and this is amplifying the banging. Do you have a basement? Try to inspect the pipe hangers that hold the pipes secure to see if you have any loose ones. Add more where you can. Other possible factors that can contribute to water hammer is if the pressure builds up too much in the hot water line downstream from a water heater. Code requires expansion tanks to be installed in conjunction with the water heater to allow the pressure buildup to not expand the hot pipes too much. This could certainly be a contributing factor. Did you recently spike the temp of the hot water heater?
    • See 2 previous
    • Mic M Mic M on May 01, 2014
      @Yair Spolter It might be a while, going under house is not hubbys "forte". First have to convince him there is problem. Thanks, Mic
  • Mic M Mic M on Apr 30, 2014
    Thanks for the advice. Will be going to hardware store.
  • Mic M Mic M on Apr 30, 2014
    Well, if the drought doesn't come to an end in California, we will too. Thanks for help. Mic
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