Lawn Sprinkler Systems Inspection Checklist
A vacuum breaker is recommended, as it is designed to prevent dirty water or foreign matter that normally accumulates around pop-up spray heads from flowing back into the potable water supply due to a negative pressure in the line. Since it is a relatively simple device, it is generally no larger than a few inches in diameter and in height.
In addition, the vacuum breaker has an atmospheric vent that is sealed when water is flowing to the spray heads. If there is a problem in the supply line and the water pressure drops to below atmospheric pressure (vacuum), a mechanical float drops, opening the atmospheric vent. This, in turn, allows water to enter the piping system upstream of the spray heads, thus preventing dirty water at the spray head from being siphoned back into the supply piping.
When checking the lawn sprinkler systems, make sure the vacuum breakers are located at least six inches above the level of the highest sprinkler head. They may be located near the foundation wall, or, in some cases, the piping may be in a well adjacent to the foundation, similar to a basement window well. The vacuum breakers and the electric solenoid valves that control the water flow to different zones are usually located in the same general area.