We're getting a new septic system, as the house we bought in July has a failing one. Forgive my ignorance on aerobic septic systems...the system described to me by the engineer is called low-pressure-dose, and it evidently uses irrigation line 6" deep to transport "waste" water through the soil. The engineer is curt and rather unpleasant, and says that i can "only grow sod" over the irrigation lines. I think this is probably just habit or lack of vision on his part, but I'm wondering if you wise people can tell me if there is some hidden downfall to growing a variety of ornamental and edible plants there? He said "roots will clog the system." Roots don't clog irrigation lines in a freshwater irrigation system, so why would they do it with the lines from a septic system? The system is sized for 475 gallons (house, guest house, and RV pad)--WHY would I waste 475 gallons of water a day? That seems ludicrous. I live in central Texas, where summertime water is incredibly scarce, and I am envisioning a lovely garden over the drain field. Am I naive or otherwise misguided?