Just back from a 4-night camping trip with a question about my 2108DS water pump. We were plugged in to shore power, and our fresh water tank was full. I noticed water pump very occasionally came on, just for a moment, even when we hadn't turned any faucets on. My first thought was a water leak, but I checked all the usual suspects and found none. Could there be a small leak under the floor? Or is this normal? Thanks for any suggestions.