I'm on catchment and use a Shur-flo dc pump. It gets its power from
solar charged batteries. While my own
solar system powers my house, you could set up a minimal simple system, nothing fancy.
At one time I used a similar pump down in my
greenhouse. I had two batteries, a simple charge controller so that the batteries wouldn't fry on a sunny day, a small solar panel. I hooked the pump up to the batteries via heavy duty alligator type clips (bought the wire & clips already assembled from Walmart) which I had wired to the pump. No on-off switch. I just clipped in the alligator clips anytime I wanted to water the plants. Couldn't get much more simple. Just had to be smart
enough to be careful so that I didn't fry myself. Not much different than hooking up a new car battery.
They
sell pump kits for exactly what you are looking for. I've seen them in my
local solar store.
Perhaps you
should check out pump systems sold for small boats or RVs.