"All of which is to say that the water pump does need a non-trivial amount of current, but since it's only on sporadically for short periods of time, it doesn't consume a lot of the charge stored in the battery. "
Excuse me but isn't that basically what I posted? :h
"The water pump may be a "significant" drain but it is only on for very brief periods of time. They typically draw 5 - 6 amps {but that's per hour}. A 10 minute shower is about 1 amp. You will run out of water waaaay before you drain your batteries."
It's nice that we agree but the point we both made is exactly the same.... water pumps do not drain your battery bank.
:B