If a home has good water pressure from a supply that's not dependant on the grid,
you can get a water powered sump pump. I have one (1), but I have 4 sump holes.
(I have 4 because our basement floor is very near the local water table)..
So, my main anti-flood system is old 120vac sump pumps.
The water powered pump would still be useful during a grid-fail + heavy flooding.
Since the basement floor is level, a 1/2" of water is going to fill up the 4 sumps holes.
From Amazon: