I have read the messages on sump pump concerns. I have moved into a townhouse which has a sump pump. My concern is recently I have noticed the pump is coming on every few minutes. However, It doesn't seem like the water is draining out. The level has remained the same,which is maybe a little over half full. It may be a little higher now. I wondering if it is working. Should the pump drain the majority of the water out? What is a safe level?