I designed my own irrigation system and installed it myself. I wanted to be able to water on hot sunny days when the lawn really needs the water. To prevent the lawn from being put into shock, I decided to route my supply line directly from my hot water heater. This way, the water won't evaporate as quickly, and the lawn won't be shocked by the extreme temperature changes. Also, since my area is lower in potassium, I've replaced my salt pellets with potassium chloride in my water softener. I've then routed my irrigation to use only hot post-softener water. I can't wait to see the results. I wonder why no "professional" has thought of this before.