One thing I never got SPOILERS

I have watched this film 4 times I think, but I never got this, and I am not French.
Florette's brother, who owned the farm with the spring, before Jean inherits it, how did he make a living and where did he get water?

They did talk about that the spring was in use when Cesar was young and Florette lived on the farm. Her brother did not seem like the kind of man who needed much, and the villagers did talk about that the land was neglected, and he let the spring become blocked up. Wouldn't he still need a water supply?

Did he have enough in that tank (or whatever it is called) where Jean also gets water? The tank that quickly runs dry when Jean starts growing his crops.