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My property has a lawn irrigation system that is supplied by a shallow well. It has worked satisfactorily for the last 4 years that I've owned the property. Recently the pump lost prime and I had no spray from any zone. I replaced the check valve in the supply line - it was allowing water to drain back and the pump was losing prime.
After replacement of the check valve the pump primed and all 5 zones worked well upon testing until the next scheduled cycle. When the system starts the sprinkles will pop up and spray then sink back down and it will take between 2 to 5 minutes for the first zone to start spraying fully and then the system runs correctly through the cycle. I can turn the system off for several hours or longer and repeat this scenario starting on any of the 5 zones.
I've hooked up a line from city water to the pump priming hole and everything works properly, water flows from the sprinklers quickly.
I did repair a leak at the gasket at the end case of the pump. I can find no leaks on the supply side for the area I can see. I have started to dig up the supply side line with the intent of checking for leaks and replacing the foot valve but I've found the line splits at a tee and it appears there are at least 4 pipes that are teed into the ground to supply water to the one pump that is in the system. The vertically teed pipes are around 6' to 8' apart for the ones I can see. I haven't dug up the whole supply side lines at this time. I can only assume that all vertical drops have a foot valve on them but that is just an assumption at this point.
With all this said my thought to solving the problem was water was draining back at a point before the check valve. Does this seem like a reasonable conclusion?
What else should I be looking for that may cause this problem?
What is the best way to find a leak, if there is one, on the supply line. I dread having to dig up all the lines.

Any input will be appreciated. Thank you.

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The type of system you have makes a difference. In my area jet pumps are quite common and they do deprime from time to time when the foot gets stuck open. They also can have issues with the jet assembly or the pump. How do you know if you have a jet? There will be 2 pipes going down the well with the motor at ground level or in a pump house.

A submersible pump usually doesn't deprime because the pump is below the water level but many times they do have a check valve up top.

A self priming shallow well pump is another type but these sometime do need water in the pump if the water level is low and they usually do have a foot valve. As these pumps age and do not produce enough vacuum or if the water level falls below its lift value they quit working.

I would be pulling the lines down the well shaft as jets are usually 50’ or less in my area and single pipe shallow well are around 20’ so both are usually easy to pull up and check the foot & or jet. If those are good the pump could be worn out.

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  • Thanks for your reply Ed. I have a self priming shallow well pump. It's a Craftsman Hydroglass High Pressure Sprinkler Pump. If the lines down to the well were in a shaft I would not hesitate to pull them. I don't believe the well drops are inside of a case or shaft and I think a lot of digging will be required. I think the well drops were driven in or the earth was dug out and pipes were installed. I haven't gone more than 3" on the vertical drop. I'll have to go a bit further to tell how they were installed. Is it possible to perform a vacuum test on this pump?
    – James Coll
    Mar 18 at 21:56
  • I would check what your static water level is. I want to say over 28’ and they won’t prime I have found that a few times in my area where the owners thought the pump was dead but the water level was at 30’. a vacuum gauge on the inlet of the pump can test the pump. I use a mechanical gauge it looks like a mechanical pressure gauge but the dial is backwards full scale 30” of mercury would be aprox 34’ but 25-28 is the best I have ever seen the gauges are cheap 10-12$ just make sure to get 30” of hg not 30” of water column, I made that mistake many years ago after messing up my first one.
    – Ed Beal
    Mar 18 at 22:52

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