@c You must have a different sort of system than I'm used to. I've never run into pumps for supply, only for drainage (sump pump, condensation pump) where gravity was not your friend.
I have a hot water tank. It happens to be gas powered, but if not, that would just mean a power outage would affect its ability to keep it heated and replace used hot water. It's inline with the supply, so pressurized, which is good, because it's in the basement underneath the ground floor and attic. It heats what it holds. Using hot water draws from the hot lines piped from it, and fresh water flows in, and if the temperature drops enough, it picks up heating some more. It's not tankless so not super powerful - expectation is you never drain the tank in use, and it has time to heat at its leisure after, so it's sized accordingly.
How's your system set up? Is it unpressurized well water as supply?
// @peemee @kdfrawg @literary @jasonechols