If you turned on your water pump and didn't have the water heater by pass valve in the correct position, your hot water tank filled, so you will need to drain it.
As others said, take the caps off your low point drains.
If you have access to an air compressor, get a "blow out" plug and blow the lines out. It connects to the city water connection.
I get the wife inside and use a blow out plug to have her open every faucet and blow them out.
2015 32 Foot Rockwood 8289WS 5th Wheel
2017 GMC 3/4 Ton TV