Have you purged your underground sprinkler system yet? If you haven't, it's time to do it now.
Here's why. Most liquids continue to contract (shrink and become more dense) when they get colder. That means they take up less space. But water has a unique property that causes it to start to expand when it reaches about 39 degrees. Then, gradually, it begins to contract again, but it still stays less dense than water.
Think of it this way. When water gets cold, what happens to the ice that forms? It forms on the top of the water, like a lake for example. This happens because ice is less dense, which makes it float. It's the same reason that ice cubes -- or even icebergs -- float on top of the water.
So what does this mean for underground sprinklers? Imagine you have a closed, sealed water pipe, full of water. You cool off the water until it expands, but it has no place to go. So what happens? POP! Your water line ruptures. This is the same reason you get burst pipes in walls, including outdoor water spigots.
People are under the impression that underground sprinklers lines and water pipes only burst in really cold climates. This is a myth. Because water expands at 39 degrees, It's not the freezing that's the problem. Here in Puget Sound, while the winter temperatures are relatively mild, we do, fairly regularly, drop to 39 degrees and below. What's worse, for outdoor sprinkler lines, is that our temperature regularly drops below 39 degrees and then goes back up. That means the water in the pipes expands, then contacts, expends, then contracts, over and over and over again. This process can gradually weaken the integrity of the pipes.
By purging your sprinkler system, we shut off your sprinklers water supply, and then we blow all the water out of the system with pressurized air. With no water in the system, all that's left is air (a gas), which can easily and safely expand and contract in the pipes.
So if you haven't yet purged our underground sprinkler system, give us a call. It's a quick and inexpensive procedure that could very well save you hundreds of dollars of expense from burst water lines.