We left to go out of town to a funeral on Monday morning.  The high for the day was roughly 40 degrees with a low of 20 something.  The following day about lunch time we arrive home to find water flowing down the alley from the overflow pipe and the water level in the pool was low.  I could hear water running and my husband was able to see that the overflow pipe had a crack in it.  But.... I have noticed that the water in pool stays constant if the pump is not running.  So is this a combination of the overflow pipe and a return both leaking?