Ideally the lawn sprinkler system should be blown out and winterized when a freeze occurs, but sometimes a late-season freeze will catch a homeowner unawares and water in the system will freeze. When water freezes, it expands, which puts pressure on the various components in your sprinkler system. Frozen water in the system can cause major issues that will require prompt repair before the system can be used again.
1. Sprinkler Heads
Freezing water in a sprinkler head or in the line just behind the head expands, which can crack the sprinkler emitter head severely enough so that it no longer works properly. Water may bubble out instead of spraying, or the sprinkler may shoot a fountain of water straight into the air instead of spraying properly. If the damage is limited to the sprinkler head, then you can simply replace the damage heads in order to repair the system.
2. Manifold Box
The manifold or control box is usually near the home or water supply line. It will likely have a green or brown cover that you can lift out in order to access the control valves for your sprinkler system. If freezing damaged anything in the box, one of the first things you may notice is standing water inside. You should also expose the valve taps and line connections in the box for damage or leaks, as these must be repaired before you water the lawn again.
3. Underground Lines
One of the more frustrating places to suffer freeze damage is in the underground water supply lines, mainly because these are harder to access for inspection or repairs. The two main symptoms of a freeze-damaged line is a loss of water pressure at a sprinkler head or a wet spot above a line when the system is running. A repair service must dig up the line and replace it if a freeze has caused it to crack.
4. Aboveground Pipes
Some systems have aboveground pipes or surface drip irrigation lines. These are more prone to freeze damage since they aren't insulated in the ground. Symptoms of damage are the same as for underground lines, but you can at least inspect them visually for leaks when the system is in use. This makes it easier to spot the damage as well as to repair or replace the broken line.
Contact a sprinkler repair service if you suspect that freeze damage has affected your system.