View Full Version : Noisy water lines - unable to determine cause

06-26-2010, 06:48 AM
About 2 weeks ago I started getting a water hammer like noise from my pipes. The "bump, bump, bump" repeats about 2 times per second and and doesn't just happen once - usually about 4 or 5 times. It sometimes happens when shutting off faucets and sometimes happens when nothing appears to be running.

I have city water and am about 500 feet from the street. The run to the house is 2" PVC with slip joints. No leaks that I can determine. The house is about 5 years old and we haven't had this type noise before.

I have copper pipe in the house and two bladder tanks - one at each end of a fairly large house - the tanks are about 45 feet apart. The one farthest from the water supply is fairly directly connected to the mainline at the inlet to the water heater. The closest one is also at the inlet of another heater not that close to the main line connection.

I checked the charge on the bladder tanks with water pressure off and found it was very low - about 15 psi on both. Thought I had found the problem and aired up the tanks. Still have the issue.

I have shut off some of the toilets, etc to try to isolate what might be causing the problem but have had no success.

We have a water softener. We have no water pressure regulator and I know the pressure does vary some. Am thinking of putting a gauge on it. Not sure if the pressure spikes (I assume that is the issue) are from the water supply of from something inside the house. Don't know that the gauge will help determine the source.

This is making us crazy as it happens at all times of the day and night. How do I figure out what this is? I would think if a valve is opening and closing to cause the noise I would see water flow somewhere.

06-26-2010, 01:45 PM
PRV might be the culprit. Toilet fill valves can cause that as well. Get a gauge with a 'tattle-tale' hand that shows peak and see what it says after a day or so. The PRV output should be fairly constant.

06-26-2010, 07:16 PM
Thanks for the suggestion of PRV but it is difficult to check... :)

We have no water pressure regulator

I have checked the toilets by shutting them off and still got the noise. I cycled the bypass valve for the softener and it seems to be better but not gone. I think I will have to simply shut off each fixture one at a time to eliminate each one.

06-27-2010, 08:18 PM
I have eliminated all the toilets and most of the other appliances. A few things don't have individual shut offs or are hard to get to like the icemaker so those haven't been shut off. The only thing that really makes the noise stop is shutting off the main line into the house. (but neither side of the valve looses pressure - I can't hear water flowing when I reopen the valve) I am starting to think it is something in the water meter (out by the street about 500 feet from the house) or in the line from the meter to the house. The line is 2" PVC 1120 with rubber gasketed joints. I think those couplings are very reliable but fear that may be the issue. Anyone heard of a problem with them? If a coupling was not engaged enough I would think that would cause problems during colder weather rather than warmer weather(due to shrinkage of the pipe). Any idea how I determine if it is the meter or the line? I suppose I could turn off the line where it comes off the meter and do a pressure test of the water line from house to meter. Any way to tell where in the 500 foot run the problem is? This is sounding expensive...

Anything I should be asking the water company about?