Q. What is Pressure Compensating?

A. Drip systems apply water to plants at very low flow rates. This minimizes evaporation losses and limits the water to the root zone of the plant by putting water where it counts. 

"Pressure Compensating", or "PC", is a term used to describe an emitter that maintains the same output at varying water inlet pressures. Therefore, PC drip emitters compensate for uneven terrain, the length of supply tube, and varying inlet flows. 

PC drippers facilitate more controlled watering, as each drip emitter performs to a preset flow rate (e.g. 1 gallon per hour), allowing water emitted over a length of time to be easily calculated. This ensures more efficient watering, reducing the risk of overwatering or underwatering. 

A non-compensating drip emitter will have varying output flows at varying inlet pressures. Therefore, the flow will vary along uneven terrain, and each dripper may emit a different amount of water depending on its location on the supply line. The pressure on a drip emitter can vary due to the slope of the land and the length of the supply tube. 

If an irrigation system is installed down a slope, there will be higher water pressure at the bottom of the slope than at the top, and non-compensating drippers at the bottom will emit more water than those at the top. PC drip emitters will emit the same amount of water all the way down the slope, providing more even watering on uneven terrain.