I am on a well and have a sump that handles the drain from the basement stairs. I installed a Zoeller 507 battery backup sump pump in series with our regular sump pump the night before Irene hit last year. My power went out and that baby kicked in and pumped water all night long, keeping the basement bone dry. It is an efficient dc pump that is powered off a marine deep cycle battery. Bought a spare battery yesterday, although it can pump for about 7 hours continuously off a single battery.