Sometimes a canister filter and an adjustable pressure regulator are installed on the supply line leading to more than one automatic valve with each control valve controlling a separate circuit. Be sure that the casing of the filter is strong enough to take full, constant water pressure, and use an adjustable brass pressure regulator.

Also, if installing a fertilizer dispenser ahead of a manifold of valves, a reduced-pressure vacuum breaker is usually required. If you have any questions regarding what backflow requirements are in your area, give your local water company a call. You will also want a shut-off valve upstream (ahead) of the entire head assembly to facilitate working on the individual electric valves should they require maintenance, or to facilitate draining and filling the fertilizer dispenser.