I just had a new underground lawn sprinkler system installed by a professional. The water meter is 500' from the house and comes in on a 3/4" line all the way from the meter. My house is on a 50' hill. The water pressure was not sufficient to run the system so the installer added a booster pump, and that took care of that problem. However, now, when the sprinkler system runs, air gets into the water line to the house and we have to deal with that. Also--we have virtually no water pressure in the house when the lawn sprinkler system is running.
What I am wondering is if the pump is not pushing so much water into the sprinkler system lines that air from some source is being pulled into the house water lines.
Also--I think it may be a water volume problem and am wondering if a separate and perhaps larger water line should be run to the water meter to correct the problem.

I think you are onto the right track with the pump pushing too much. You can add an anti-backflow valve to stop water/air from getting into your home. The only other thought would be to try to zone the sprinkler so there is less of a draw at any one time.

I think it is more of a plumbing issue and would get better results there. But I will throw something out there (nobody whack me!) I think there is supposed to be a Y installed to prevent a venturi effect. Or as ballenger stated a back flow regulator makes sense.

Don

The system was installed with an anti-backflow device, so the problem exists in spite of the back flow preventer.

Do you know where in the system the device was installed? You need to check the capacity of meter as well as supply lines. Most commercial services give plenty of capacity to meter it is usually after the meter where problems occur.

Don

You have a really serious problem. It sounds to me like the pump lacks volume on the intake side and is pulling air into the line. That is bad enough, but when the ground is wet, it could pull surface water into your water line contaminating it. The back flow preventer would only prevent you from sharing your problem with your neighbors. How close does the sprinkler line take off from the water meter? You may be able to solve the problem by coming off at the water meter with a larger line. An inch line will carry at least 3 times the flow of water as a 3/4''.

Is the pump rough and noisy? It could be cavatiting and destroy itself soon.

If the back flow preventer is new, did you add an expansion tank to your water heater? When it heats, water must be free to flow back out of the water heater.

I am going to ask to have this moved to plumbing where you may get a better answer. Actually your answer needs to come from the installer, not AMHD. If he isn't interested in making the thing right at his expense, talk to the water utility. We have a legal forum here too.