IA Cheat Sheet 2026

The 30 highest-yield IA facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. What is the formula for calculating the precipitation rate (PR) of a sprinkler system? → PR = [96.3 × Flow (GPM)] / Area (sq ft)
2. Pump efficiency (Ep) is defined as the ratio of: → Water horsepower (WHP) to brake horsepower (BHP)
3. What is the primary purpose of a zone in an irrigation system? → To group areas with similar watering needs
4. On a centrifugal pump curve, what is the 'best efficiency point' (BEP)? → The point on the pump curve where the pump operates at its highest efficiency
5. During a catch can audit, how many cans are typically placed in a single irrigation zone? → At least 8–16 cans per zone in a grid pattern
6. What is the primary role of evapotranspiration (ET) in irrigation? → To estimate water needs
7. In hot, arid climates, how does the crop coefficient (Kc) of turfgrass typically compare to humid climates? → It may be higher due to greater atmospheric demand and more advective energy
8. Brake horsepower (BHP) of a pump is calculated using which formula? → BHP = Flow (GPM) × TDH / 3,960 × pump efficiency
9. In a water budget approach to irrigation management, the maximum allowed water use (MAW) is based on: → A calculated ET-based water allowance for the landscape area
10. What is field capacity in relation to soil moisture? → Water held in soil after free drainage
11. Landscape water use efficiency (WUE) is expressed as the ratio of: → Water beneficially used to total water applied
12. What is the minimum acceptable DU_lq percentage recommended by the Irrigation Association for landscape systems? → 70%
13. Which instrument is used to directly measure reference evapotranspiration in the field? → Lysimeter
14. Which controller program type allows different zones to run on different days of the week? → Day-of-week program
15. Which backflow prevention assembly provides the highest level of protection against both back-pressure and back-siphonage? → Reduced Pressure Zone (RPZ) assembly
16. An irrigation audit station flow rate is determined by measuring: → The volume of water discharged from a zone over a measured time period
17. What is 'head-to-head spacing' in sprinkler design? → Spacing where one head's throw distance equals the spacing between heads
18. What term describes the variation in application rates across multiple sprinkler heads in a zone due to hydraulic differences? → Coefficient of variation (CV)
19. What is the significance of the pump curve intersection with the system curve? → It is the operating point where the pump actually runs in the system
20. Wire-to-water efficiency of a pump system measures overall efficiency from: → Electrical power input at the utility meter to hydraulic power delivered to the water
21. Low-volume irrigation systems, including drip and micro-spray, generally achieve higher application efficiency because they: → Apply water slowly near the root zone, minimizing evaporation and overspray
22. The term 'runoff' in landscape irrigation refers to water that: → Exceeds the soil's infiltration rate and flows off the landscape surface
23. What is the main benefit of drip irrigation systems? → Delivers water efficiently to root zone
24. What instrument does a certified backflow tester use to field-test assemblies? → A differential pressure gauge test kit with hoses connected to the assembly's test cocks
25. What is 'effective rainfall' in an irrigation context? → The portion of rainfall that is stored in the root zone and available for plant use
26. What type of sensor can be wired to a controller's sensor input to automatically suspend irrigation when the soil has sufficient moisture? → Soil moisture sensor (tensiometer or capacitance probe)
27. How does slope affect irrigation efficiency? → Causes runoff and uneven watering
28. Distribution Uniformity Low Quarter (DU_lq) is calculated by dividing the average of the lowest 25% of catch can readings by: → The overall average of all catch can readings
29. Which organization is the primary authority for backflow prevention standards and tester certification in the United States? → USC Foundation for Cross-Connection Control and Hydraulic Research (USC-FCCC)
30. What does a controller's 'common wire' do? → Completes the valve circuit