Troubleshooting sprinkler system pressure

Question

Just moved into a new house and am trying to figure out the sprinkler system. The house was built in the 60's and it appears (Found the manual for the pump) the irrigation system was installed then as well. The heads don't pop up, but a small stream of water flows out and puddles up around them. If I take the heads off and run the system there isn't really any pressure coming out of the pipe. However, we took the pressure tank off and we're getting a lot of pressure from there. - Not sure how much exactly, the pressure gauge looks to be not working as well.

Here are some details about the system:

• Runs on well water with a submersible pump. Don't know where the well is though.
• Single zone for front and back yards (as far as I can tell)
• 7 heads in back yard and 5 heads in the front (that we've found so far, most were covered in the grass)
• The house was unoccupied for ~3 years, I'm assuming the sprinklers haven't been ran for at least that long.

I'm thinking there is a broken pipe somewhere or an obstruction. But where? How can I track down why and where we're losing pressure? Is there anything I can do other than digging up the entire yard?

Answer 1

Compressed air is sometimes useful for finding broken sprinkler pipes. It takes a large volume of air though. An electric compressor with a tank of 60 gallons or larger will likely have a large enough capacity (CFM), or rent a towable compressor of the sort used for pneumatic jack hammers (40-200 CFM). These rent for about US$100/day in my region.

• air escaping from a broken pipe makes a loud hissing, whereas water exits much quieter
• compressed air may cause sandy or loose soils to be thrown up around the leak, whereas water will just flood the area
• when the general area is found it's easier to excavate dry soil instead of soupy mud and to make repairs on clean dry pipe instead of muddy pipe

I suggest removing the zone valves and blowing air into each zone, one at a time. Then install caps or close valves as necessary and blow air into the main line to check it for leaks as well. The main line can be also tested for flow restrictions by applying air at one end and opening a valve at the other end.

Answer 2

I have found broken pipes by using a dowel pressing to the ground then pressing my ear to the dowel, if there is water ruling you can hear it 5/7 heads is not that many and if there are no isolation valves it probably worked fine in the past, being built in the 60’s it is probably galvanized pipe, there are many possibility’s for low flow. The first a broken pipe you have thought of, galvanized pipe also can corrode and build up on the inside limiting the flow of this is the case the pipes will need to be replaced and the pipes are old enough for this to have happened, the third thing I think of is the sprinklers may be plugged with sediment (or possibly a screen filter in line is plugged) so there are a few things to check, you stated you don’t know where the well is you can run water inside the home and use the dowel method to find the pipe (normally the well casing extends above the ground but I have seen a few that were buried (not good). Hope this gives you a way to figure out what the problem is.