Erm, that’d be because I’m not very imaginative, so focused on the river rather than other options. Not sure what the situation on a well would be, but fortunately there’s quite a few experts on drilling and geology round my neck of the woods so it’s probably well worth asking the question. Thanks for the idea.
Ah, I didn’t know that. I wonder if they have a kit with a bigger propellor than. Time for some enquiries.
Didn’t get an answer to my other Q, but …
Do you own the land down to the river’s edge, or centerline? Could you even put an intake in the water?
The title extends into the river itself - beyond centreline, in fact, as it was a fishing station before.
Apologies for missing your previous question - The house is set back a safe distance. It’s close enough to the mouth of the river to be tidal, but is 5 metres about the highest tide recorded. I’ve checked with the local councils flood planning department, and they advise me that unless sea levels rise by catastrophic levels then it’s absolutely fine.
And if they do rise by catastrophic levels, the plot slopes uphill to 15 metres higher, so my disaster plan would be to knock down the house, build up the existing jetty, and buy as big a boat as I can get down a river that’s now 5 metres deeper.
Thanks for satisfying my curiousity. I hope I didn’t seem snarky. 
There are also windmill pumps for drawing water from a well, you could erect an elevated storage tank, filled by the windmill, to provide adequate pressure.