Hooking up to commercial water

[YoungWanderers]

I wasn't able to find a definitive answer to this question so hopefully this isn't a repeat. We are on our second trip in our 79 FC (the first trip went great after learning the systems). However, this trip we are having issues with the water hookup. We followed the instructions left by the previous owner and filled both water tanks but when we turn on the water pump to use the water we just keep having water leak out of the bottom. The gray tank has been drained and all the valves are turned on so I am not sure what step we are missing. I should add that we also have the commercial line off. Literally two days ago we were doing the steps the same exact way in NC and had no issues. I am sure it is user error but any and all help would be greatly appreciated! Plus I don't want to have to be the one to tell my girlfriend we are taking campground showers.