Is 20 minutes long enough to water your lawn?

Is 20 minutes long enough to water your lawn depends on sprinkler type, soil, weather, and water needs, but generally 20 minutes per zone 2 to 3 times per week can be enough for many lawns with spray heads, while rotor zones may need 30 to 45 minutes. Lawns typically need 1 to 1.5 inches of water per week, and to determine if 20 minutes is enough, you need to measure precipitation rate of your sprinkler. Fixed spray heads often apply 1.5 to 2 inches per hour, so 20 minutes provides about 0.5 to 0.6 inches, which times 3 days equals 1.5 inches, enough. Rotor heads apply 0.3 to 0.5 inches per hour, so 20 minutes only provides 0.1 to 0.16 inches, which is insufficient and needs longer run time of 45 to 60 minutes per zone. Factors like clay soil needing slower watering to prevent runoff, sandy soil needing more frequent, hot weather needing more, and cool weather needing less affect. Best way is to do tuna can test to measure how long it takes to collect 0.5 inch, then adjust. So 20 minutes may be enough for spray heads but not for rotors.