Water pump 2005 22 international

[pgold]

We have a 2005 22 foot international airstream. We just bought it and it is our first airstream. I can't seem to get the water pump to come on. When we first bought it, the water pump came on great. The water pressure works only when a hose is attached. I was wondering what and where the things are that I should check (breakers, resets, switches, valves). Any help is greatly appreciated!