Underground sprinkler system pipes are buried to not only protect water in them from freezing and bursting the pipes, but more importantly, to keep them from being damaged by machine or manual digging.
While 6 inches is standard for most residential underground sprinklers, it is wise to allow extra an extra 4 inches for fitting and any wires you need to install. The extra room will also allow room for plantings.
When installing a residential underground sprinkler system it is always best to check the manufacturer's instructions. These instructions should outline the specifications for installation and help you with an installation plan.
Before You Install
Before installing an underground sprinkler system, be sure that you locate and mark any underground utility lines.
TIP: Our expert gardening advisor, Susan Patterson adds, "Check with your local authorities before installing an underground sprinkler system. Many cities have building codes with regards to how deep pipes should be buried."