Hi Al, thanks for the query. I'm afraid that pumping isn't my speciality at all. My preference is to use gravity if at all possible. Something that I have done here at home is to collect rain water in above-ground storage tanks. These are stored on pallets so that the base is about the same height as the toilet cistern base. The plan is to simply route a pipe around to the bathroom and plum the cistern, and put a stop-valve on the mains supply. The fill may be quite slow due to the low head of water, but there is usually no rush between flushes.
Other than that, I'd look for either solutions to use less of the water that I do pump - or else keep searching for easy ways to meet my pumping needs.
If you want to avoid electricity, would an on-demand hand pump work for your purposes?
I've seen hydraulic rams that have worked for many decades, slowly, methodically pumping water high up to raised farm cisterns, using the power of the stream that they are pumping. That might not work for a rainharvesting system, but great if you're near a stream.