Almost no pressure in 4 out of 6 zones

[texbob]

What would cause low pressure in 4 zones - 1, 2, 4 and 6 (entire front yard and zone 6 in the back of the house)? Water barely trickles out of each sprinkler head in these zones, but pressure is fine in zones 3 and 5. There are 3 anti-siphon values (see attached drawing indicated by v v in the right side of the front yard). When I open each one counterclockwise all the way, water starts to drip out. The water stops when I close the valve.

 

[WorthFlorida]

Either debris inside the pipes or the irrigation valves are bad and may need a rebuild. If you know the first sprinkler after the zone valve, remove that sprinkler and turn in the water. If the water doesn't shoot up Several feet into the air, the valve could be the problem. The diaphragm gets stiff and may not be opening fully. If the four zones problem started at the same time then debris would be a suspect.

 

[Sponsor]

 

[texbob]

Either debris inside the pipes or the irrigation valves are bad and may need a rebuild. If you know the first sprinkler after the zone valve, remove that sprinkler and turn in the water. If the water doesn't shoot up Several feet into the air, the valve could be the problem. The diaphragm gets stiff and may not be opening fully. If the four zones problem started at the same time then debris would be a suspect.

Thank you. What does it indicate if water starts slowly leaking out from the valve when I manually open the solenoids? Also, the lawn guy recently replaced a sprinkler valve that got mowed over in a zone that is still working (zone 3) . Could debris from that sprinkler head opening travel and block a different zone?

 

[HudsonDIY]

What does it indicate if water starts slowly leaking out from the valve when I manually open the solenoids?

If the valve itself is leaking you likely have a broken diaphragm in the valve.

Also, the lawn guy recently replaced a sprinkler valve that got mowed over in a zone that is still working (zone 3) . Could debris from that sprinkler head opening travel and block a different zone?

I've never heard of anything like this happening, its highly unlikely. It's a long way back up to the manifold set and into another zone even if it were the first head in the zone. On top of that the backflow preventer wouldn't allow much reverse flow if any at all.

 

[WorthFlorida]

All depends where the break was but for four zones to go out at once probably not. A lot of mud would have to entered the pipe. If you have pop up sprinklers, remove the nozzle only and below it there will be a filter screen. Remove it. If it’s full of mud that’s the problem. If not time to open valves.

 

[WorthFlorida]

....What does it indicate if water starts slowly leaking out from the valve when I manually open the solenoids?.....

Bad valves. As said before the diaphragms are dried out.