Your water supply
Test pressure with a $10 gauge on an outside hose bib (turn off all other water). Test flow rate by timing how long it takes to fill a 5-gallon bucket from the same hose bib full open.
Area to irrigate
Measure each section of lawn or planting bed and add them together. A typical front yard is 1,500-3,000 sq ft.
Sprinkler type
Rotors throw 15-50 ft and use 0.5-4 GPM each. Sprays cover 5-15 ft at 1-2 GPM. MP Rotators use less water than sprays. Drip emitters use very little water but cover only plants, not lawn.
Head layout
Head spacing should match the throw radius – heads need to spray onto adjacent heads for even coverage (head-to-head spacing). GPM per head depends on the model and nozzle.
Zone plan
Working pressure
0 PSI
after typical losses
Heads per zone
0
limited by flow
Total heads
0
to cover area
Number of zones
0
valves needed
Watering schedule
Run time per zone
0
minutes per watering
Total cycle time
0
all zones run sequentially
Each irrigation zone is limited by your water supply – only one zone runs at a time, so heads-per-zone times GPM-per-head must not exceed available flow. Plan for 20% safety margin to avoid pressure drops. Water early morning (4-8 AM) to minimize evaporation and disease. Most lawns need 1 inch of water per week; deep, infrequent watering builds strong roots.