I had a problem with my water pump this year. If I turn on the pump accidentally when hooked up to shore water backflow valve stays open and the tank over fills. I usually just need to turn off the shore(land) water and cycle the pump for a while and it flops the back flow valve into the correct position. But this year it did not work. Pump was not pumping. So I disconnected the in and out to the pump to check for blockage(none) and reconnected them. Cycled the pump for a while and Hooray for me. Maybe I had an airlock in the line. Who knows, it worked. So first make sure your pump is on. Do this when shore water is turned OFF.