As I understand it some effort is made to arrange for the projections that come off the flat roof to feed these cisterns. A rope or length of chain can be used to guide the water. If you get the water running down the chain it will tend to follow the chain even if it isn't plumb. A rough estimate is that you can divert the water something like fifteen degrees from vertical.

I once saw a system of three rain barrels that used a chain to divert the water. The chain would be transferred from barrel to barrel as each was filled in turn. You could do the same thing plumbing fittings but if all you have is barrels and chain you make it work. Also with three barrels unconnected by pipes there is no risk a leak might drain away your entire supply.

Of course in the dry season you might need to carry water in from a well to fill them manually.

The movie took place in Mexico in probably the very late 1880s, and I didn't see anything that resembled wind power in use.

Of course, this being a movie, they could have been based solely on imagination and made from papier mache or cardboard.

Sue

I think Art probably nailed it... either way it's pretty brilliant. I've seen the movie a dozen times and I never paid attention to the back ground before. LOL