My Dad had a Rider-Errickson water pump. It was a 6 X 5 IF I remember correctly. It was heavy for it's size. It was built before they made cast iron leg frame to hold the engine. We used a torch and 1" solid bar to make the 4 round legs. It had a square "fire box" under it, and, he just put a propane water heater burner inside the box, for demo's.
The water pump was brass and very small. It was originally used to pump water up to an overhead tank, when the wind wasn't running the wind mill. It did not have much power. I didn't mess with it all that much to know if it needed rebuilding or what.
Flashsteam .com has some info on modern steam stuff, and, there is 1 contributor who has a neighbor's video posted, of a rotary steam engine, running from an electronically operated boiler. Has a pump to add water to the reservoir and self regulates the whole boiler set up.
My neighbor was here last night, asking me to do some photos on the computer. He has a large Dairy farm for this area, and, a stream of water that would fill a 6" pipe easily, and it runs 200' downhill, right past his Dairy barn and remodeled house. Remote location. He is having the electric power co put in a line .
He also showed me photos of his waterfall, where hundreds of gallons per hour are just running down the hill.