I'm installing a sprinkler system, and have to install a backflow preventer and pressure regulator at the start of the line. What I don't like about this is having random bits of plumbing sticking out of my yard where they'll get hit by things, and look unsightly. There is already a stub for irrigation water inside the house (in the basement) with a shutoff valve and a pipe going back outside.
Is there an indoor or underground option for backflow preventers? Or do they have to stick out of the ground somewhere? Do they have to be higher than any point in the line past them?