This is not normal. If you have it set to city water, with water in the fresh water tank, it should not be kicking on. If it is kicking on, it is because pressure is dropping. Does it turn on other than when using water? If not, than either external/city/shore water pressure is very low, water filter is plugged or there may be a kink in a line. Note: You may know this already but, if you are going to leave the pump on, make sure there is water in the tank. If it is turning on when no water is being used, you probably have a leak.