Irrigation and Water Management
What this domain tests
Irrigation and Water Management tests design hydraulics (precipitation rate, matched heads, pressure), Florida code and water management district rules (rain sensors, day-of-week limits, backflow), and scheduling that applies water no faster than the soil can absorb it.
Rules that show up on the exam
- Florida law requires a functioning rain sensor or similar shutoff on every automatic irrigation system, and it must remain operational, not just present.
- Water management districts (SFWMD, SWFWMD, SJRWMD, SRWMD, NWFWMD) set year-round day-of-week limits, typically two days per week. Local utilities may be stricter, and new plantings get a documented establishment window.
- Design head-to-head spacing with 50-60% overlap, keep precipitation matched within a zone, and size flow at roughly 75% of available safe flow.
- Keep spray heads off pavement and out of the 10-ft fertilizer-free zone along water bodies.
- Reclaimed water needs purple pipe, Do Not Drink signage, and a reduced-pressure backflow assembly at the potable connection; chemical injection also requires RPZ protection.
- Use cycle-and-soak schedules on Florida sands: short repeated cycles beat one long run.
Worked example
Six rotors at 3.0 gpm each cover a 60 ft by 45 ft zone, 2,700 sq ft, for 18 gpm total. Precipitation rate = 96.25 x gpm / area = 96.25 x 18 / 2,700 = 0.64 in/hr. To apply 0.75 inch per week, runtime = 0.75 / 0.64 x 60 = 70 minutes weekly. Split that into two weekly cycles of 35 minutes, and split each 35-minute cycle into two 18-minute runs about an hour apart so the sandy soil absorbs the water instead of running off.
Traps
- Mixing sprays and rotors on one zone, which unbalances precipitation and dries the edges.
- Sizing pipe and valves to available flow without accounting for pressure loss.
- Treating the district schedule as permission to water regardless of rain or plant need.
- Forgetting that the rain sensor must still function after installation.
- Confusing distribution uniformity with pressure: good pressure with poor overlap still leaves dry spots.