The easy way to test if it is this is to turn the water off to the toilets when the hammering is happening. If you kill the water to the toilet (usually a valve right before the tank) and the hammering stops it's a good chance that it is the fill valve in the tank. If multiple toilets just check each one.
Plumbing Knock (water hammer)
- Thread starter josh4cy
- Start date
The easy way to test if it is this is to turn the water off to the toilets when the hammering is happening. If you kill the water to the toilet (usually a valve right before the tank) and the hammering stops it's a good chance that it is the fill valve in the tank. If multiple toilets just check each one.
I turned off the water to each of my toilets, 10 minutes later the knock started so those are ruled out.
Running water can stop the knock for a while but not always. Hard to know what water usage is at other homes. And hard to know if the knock would stop with out me doing anything. I have not found a consistent way to get the knock to stop other than shutting off the main valve.
I can feel the knock on the pipes. But the knock doesn't seem any harder on the check valve.
Is the check valve the first thing i should replace. Should I have it removed as a test?
Running water can stop the knock for a while but not always. Hard to know what water usage is at other homes. And hard to know if the knock would stop with out me doing anything. I have not found a consistent way to get the knock to stop other than shutting off the main valve.
I can feel the knock on the pipes. But the knock doesn't seem any harder on the check valve.
Is the check valve the first thing i should replace. Should I have it removed as a test?
I should have looked closer at the picture you posted of your pressure tank.
If you shut the valve you labeled shut off valve, you still get the noise. If you then shut the valve you labeled main shut off, the noise goes away. If you then open the main shut off valve while leaving the other shut off valve closed, the noise comes back. Is this correct?
If so, I would say you have isolated the problem down to your pressure tank or check valve.
Here is a video that can show you how to do a couple simple checks on your pressure tank. In your case, when you get to the part of where you cut power to the pump, just shut off the main shut off valve. To find out how much air pressure should be in your tank, find out who maintains the community well pump and ask them.
Basic steps are:
1. Check to see if water comes out of top of tank when system at normal pressure.
2. Check air pressure in tank when drained or at least depressurized. Should but a lot higher than what is reading on pressure gauge installed by bottom of tank. Add air to tank to level recommended by people who maintain public system.
If the pressure tank seems to be ok, then go ahead and replace the check valve. It is not hard to do but will leave it up to you if you need a plumber to do it.
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