Question
I live in the chicago area...cold winters. I just bought a house with a lawn sprinkler system. How do i shut down the system for the winter season. I've heard your suppose to "blow the lines"...what does that mean exactly.

thank you

Answer
When water freezes it expands in size (that is why ice cubes float). The force exerted by this expansion is so great that the  water trapped in cracks in rocks cause those rocks to split when it freezes. And if the pipes in your sprinkler system are full of water and it gets cold enough to freeze (32 deg.F) the pipes will break. You avoid this by emptying the lines in anticipation of a freeze. At the end of each sprinkler zone there should be a screw cap. This is opened and the water will drain out of the pipes. The mechanism might be different from one system to another; I do not know because I have never had to deal with this particular problem.