I am wondering if there are also any license costs for accessing the artesian water - having a bore? This may also be something to factor in to your thinking. Overall though, I really your thinking. When water availability is a real problem, we do need to be imaginative about firstly, how to reduce the amount of water we need to use - drip reticulation is a good solution, and secondly, how do we ensure that as much as possible ends up being available to the plants - not lost by evaporation. I assume you keep everything well mulched.