My neighbors installed a sprinkler system and now whenever it turns on the pipes in my house knock.

Question

Since it is turning on at 4 am and running till 7 am and it is in my master bedroom wall where I hear it worst, I really want to figure out what is going on. What could it be? The only thing I can think of is that they somehow hooked up to my water supply instead of their own but that doesn't seem too likely. Any ideas... or ideas on who I could call to find out (besides the neighbors themselves) would be appreciated.

Answer 1

call the water company, because it sounds like they didn't install their lines right...   maybe neglected an air break or something..  contact the water company and tell them what's going on and ask if they can come check it out.

Answer 2

I am a  licensed irrigator in Tx.  What is going on is water hammer, when their sprinkler turns on/off the flow of water creates a shock wave in the water lines.  If they are not hooked up to your water meter then they are running too many heads and\or too small of pipe.  

Any way the rememdy would to be to install a spring loaded check valve after the DCA, backflow prevention device, on their sprinkler.

Notify the water company of this and make sure they have the backflow prevention device installed.  If it is not then the system is illegal.  This device will not stop the water hammer but is required to keep the drinking water safe.

The water hammer is due to the water moving through the pipes too fast and when it stops the pressure momentarily increases greatly.  This could mean problems for your water utiltiy and you.

Also, to check if they are hooked to your meter go out and watch your meter when their sprinkler is running.  If your meter is spinning really fast then you are paying for their water.

If all this goes no where you might install a water hammer arrestor on your water line coming into your house but consult a plumber first and if they say "what?" find another plumber.

Answer 3

The water department can check the pressure at your house when an spigot is opened on their house.   There may be a restriction in the incoming supply that feeds each of your water meters.

If the pressure in the incoming pipes is above about 50 PSI, you could have a pressure-regulator installed in your house.    If not, you could have an anti-backflow valve installed.   Either one of those should prevent the sudden drop in pressure when the neighbor's sprinklers turn on.    If your pipes make noise when their sprinklers turn OFF, only the pressure regulator will prevent that, the backflow valve will only work for the turning ON sound (i.e. the sudden DROP in pressure).