Good sprinkler pressure will supply a large amount of water, evenly, over the largest area as possible in the shortest amount of time. This is achieved with properly sized water lines and appropriate number of sprinkler heads for the water available. Weak water pressure doesn’t help.
Decreasing the diameter of a water line will increase the water stream at the nozzle, however it also reduces the volume of water being delivered. A tiny hose might have a strong stream but it will not deliver enough gallons per hour to properly water the lawn. So don’t try a smaller hose to get my oscillating sprinkler to get the heads to come out of the ground or to spray farther.
If you put too many sprinkler heads on one line the sprinkler heads will not lift up from the ground. For example at the old location of Gilbert’s Hardware we could only put two gear heads (a gear head is one that goes back and forth and can send water up to 40 feet) on a zone. In the new store, (just 150 feet away) we have four gears running at once without any problem.
The reason is the old one has a 5/8-inch water meter, the same as most homes in our area. The new is a one-inch water meter that can deliver twice the gallons per minute.
To get your system to run better you will probably have to dig up some of your system and split it into several zones. Depending on the layout of your system you may get away with minimal digging.
Another solution to getting all the heads to come up is to get a larger water service installed to your house. However, prepare yourself because this is not for those that are weak-of-wallet. A new water service to the house could cost over a thousand dollars.
When designing a system do not use more heads on a zone than the system can deliver. Different types of sprinkler heads require different volumes of water to operate properly.
The gear-head, like an impact sprinkler can use over three gallons per minute, but it covers a large area of lawn.
The pop-up head can mist an area up to 15 feet. Heads can cover a small area to a fifteen-foot circle. They can use about one gallon per minute depending on the type of head. They are used around sidewalks and boulevards.
An amateur can check the capacity of a system by building it on the lawn and testing it first.
My advice to you is to find the closest area near the supply from the house you can split the sprinkler system. Dig down, cut the line and connect your supply to one of the existing lines. Turn on the water and see if the heads pop up correctly. Try the same procedure to the other side and if it works.
If splitting your system at this area works all you have to do is add two zone valves so your system feeds only one section at a time. If this does not work you may need to find another area to split the next largest group of sprinkler heads and do it again.
Keep that lawn watered or lose it.