For the evaporative cooler, see what the costs for a well are. You'll
probably want/have one for the yard anyway. Then make sure that the
holding tank is under cover or underground. That will cool the water
also and help the wetwall.
When I water, I have to use city water and it comes out of a hose.
If I water in the afternoon, it's necessary to run the water a couple
minutes and get rid of the solar heated water already in the hose. In
the am, the hose is shaded.

jimwatts