I am using well water. The static pressure measured with the outside faucet is 60 psi. When irrigation system is turned on, the water coming out of all sprinkler heads in any zone is weak. I guess the pressure at sprinkler heads is low. When irrigation system is on, water pressure inside the house is very low too and the PSI I read at outside faucet drops to 20 PSI. What could be the problem? Can low water in the well cause the problem?

Thank you!

  • 2
    The problem is that the well is not producing enough water for the sprinklers. the cause of that cannot be determined from the information given
    – Jasen
    Aug 27, 2020 at 10:23
  • Hello, and welcome to Home Improvement. When the irrigation system turns on, does the interior water pressure drop immediately, or over time? And, you should probably take our tour so you'll know you'll know the details of contributing here. Aug 27, 2020 at 11:45
  • Simplest effective solution might well be to convert the sprinkler system so it runs individual zones one at a time, not all at once. If already doing that, smaller zones.
    – Ecnerwal
    Aug 27, 2020 at 11:52
  • Pressure and flow rate are not the same. You have plenty of pressure from the pump, but low flow rate. This could be a factor of your well, the pipe sizing, the distance/depth.
    – mark f
    Sep 29, 2020 at 15:39

4 Answers 4


It sounds like your well is not able to provide the flow rate needed to supply your sprinkler system.

Let's say that your well/pump/plumbing are able to provide 5 gal./minute. If you exceed that rate then the pressure will drop. It's unlikely that low water level in the well is the source of your problem as in that case the pump would start sucking air and you would notice the air in the system as it "burps" out.

I'd start by checking your plumbing for suitable sizes of pipes and fittings and see if there are any obvious problems such as way too small pipes. If that fails to reveal any issues you likely need to engage a well service professional who can evaluate your well and pump and make any recommendations that might correct your problem.

Keep in mind, especially if your well and pump are old, that fixing this may involve replacing the pump, drilling a new well, running a new pipe from the well to the home, etc. In other words, it may be expensive.


There could be several causes. Is this a new problem? Have you made any changes to the irrigation system? The most likely cause is you are simply using too much water than the pump can provide so the pressure drops until the delivery rate matches the consumption rate. Reducing the number of heads on a zone would address that issue. You may have to increase the number of zones to cover the same area. I assume you are only running one zone at a time, right?

It could also mean your well isn't producing enough water anymore, but the production rate of wells is usually pretty consistent. Still, the water level in your well might be dropping, making the pump work harder. And the pump could be wearing out. They don't last forever and maybe slowly failing.


One thing that has not been mentioned is what happened to me. I suppose through the minor vibrations caused by the pump turning on and off, over time, my main shutoff valve rotated itself into the off position. At first, pressure was dropping when more then one thing was using water in the house, eventually, no water at all.

When I went to turn the shutoff off, I noticed it was already off. So that is an easy thing to check before looking at other things. If it's a gate valve, also make sure it is fully open (and then back off half a turn to help prevent it seizing).


Your question is a bit misleading, you state: The static pressure measured with the outside faucet is 60 psi. When irrigation system is turned on, the water coming out of all sprinkler heads in any zone is weak." I am assuming the so PSIG drops with the sprinklers, if that assumption is wrong you have a restriction or partly closed valve in the sprinkler feed.

I have city water and the sprinklers did the same thing, I added a length of 1/2" copper tubing in the feed and it now works great and the inside pressure is good.

I am assuming the pump does not shut off, this is the way I would expect it to operate. The pump can pump so much water at a given pressure. Use more water the pressure will drop, use less and the pressure will go up.

Many sprinklers will allow you to adjust the flow. If you have that type of sprinkler head lower the flow and let them run longer. The end result the area gets the same amount of water in the end. That would be by far the most cost effective. As mentioned earlier you can add more zones.

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