Underground sprinkler systems must be turned on slowly at the begining of the watering season to prevent damage to the pipes and sprinkler heads.When you restart your irrigation system each spring, it’s important to follow the correct startup procedures so that you do not damage the system. Starting up the system is not particularly complicated, but it’s more than just turning on a valve. Be patient when turning on your irrigation system after it’s been winterized because if not, you could have a geyser of water filling up your yard and costly repairs.
The key to preventing system damage is to turn on the water slowly. This allows the pipes to pressurize and all the air to purge. Turning on the water source too abruptly can cause pipes to burst. Even if your pipes don’t rupture right away, you could create stress on the pipes that leads to damage and leaks down the road.
Hometips.com has a good explanation on how to properly start your irrigation system:
“Begin the process by filling the main line of the irrigation system (located between the water source and the zone valves). Slowly open the shutoff valve that controls the water supply to the entire system. A quarter turn or so is all you will need. Take your time and remember that the water has to travel the entire length of the main line. Once the main line is filled, proceed with filling each zone, again, by very slowly opening the zone valve manually.”