First, Unless you have water in your water heater. Don't turn that on.
Second, Like others have said, you can hook up a hose and not need the pump. Personally I wouldn't do that. Why? Black and grey tank size. Limit the amount of water your guests have to use by only putting in the fresh tank whatever the amount the grey can hold.
That way they call you when they run out of water. Not when the shower is overflowing onto the floor of the trailer. When they call you to tell you they need water, you empty the tanks and add water.
