Lots of homes in the south are built on slabs with no basement. Very few homes in AZ have basements. So it is typical to put sewer in the slab and water in the attic. How would you do it? In my home in AZ, we are served with high pressure lines and a regulator before it goes into the house. Sometimes the regulator fails and a leak in the attic results in a sprinkler system that goes undetected until the ceiling falls. Makes a huge mess but happens occasionally. I shut the main valve to the house off if I'm going to be gone for a day.