Irrigation glossary

Zone - the sprinklers or emitters on one valve, running together. Valve / solenoid - the electrically operated valve that opens a zone when the controller energizes it. Controller / timer - the device that decides when zones run. Station - a controller output wired to one zone's valve.

Precipitation rate - inches of water per hour a device applies. Sprays are high, rotors are low, which is why they can't share a zone. Head-to-head coverage - spacing heads so each one's spray reaches the next, which is how uniform coverage is achieved. Matched precipitation rate nozzles - nozzles designed so different arc patterns apply water at the same rate.

Backflow preventer - the assembly that stops irrigation water being drawn or pushed back into the potable supply. Backsiphonage - backflow caused by a pressure drop in the main creating suction. Backpressure - backflow caused by higher pressure on your side pushing water back. Cross-connection - any physical link between potable water and a non-potable source.

Evapotranspiration (ET) - water lost from soil and plants combined; weather-based controllers use it to size watering. Cycle and soak - splitting a runtime into shorter intervals so water absorbs instead of running off, which WaterSense recommends on clay soils and slopes. Drip / emitter - low-flow devices delivering water at the root zone. Swing joint - a flexible connection that protects buried pipe when a head is struck.