Irrigation systems are designed to work at different pressers and is measured is pounds per square inch (PSI). 30 psi for spray heads and 45 psi for rotors, too much presser will result in mist which is a huge indicator that you are wasting water and your hard eared money. when not enough presser heads and rotors do not preform correct which also leads to water waste and poor coverage. newer system come with a 45 psi regulator at the start of main lines. My favorite and most effective is at each head or rotor. These up graded heads come with a 3yr warranty from manufacture. Presser regulated heads or PRS heads pay for themselves in about 3 to 5 years depending on city presser and usage.