the pump is equipped with a pressure switch, so that if the pump circuit is on, and you have water in the tank, you will have water on demand when you open a faucet.... and when you shut the faucet off, the pump will run til the system is fully charged with pressure, then automatically shut off....
in normal use, when you are at the trailer, you can leave the pump switch ON.... when traveling, or when you are going to be away from the trailer, shut it OFF.... (some of us leave it on all the time the trailer is in service, but we are taking a risk, as if a line should break while we are traveling, the pump will deliver the entire content of water in the tank out thru the broken line, which could be anywhere within the trailer.... its not so likely an occurrence, but it will be devastating if it should happen.
if you hear the pump start to run without someone opening a faucet, shut the power to it off immediately, as it has just sprung a leak somewhere..
if you hear it briefly cycle during the night (or at any other time), it means there is either a very small water leak somewhere, or there is a fault with the check valve within the pump, which in itself is not an emergency like a water leak will be....