Flow rate

Flow rate is the volume of water that passes through the dripper during a given unit of time.

Some drippers emit 8 liters (2 gallons) of water per hour, and some low flow rate drippers emit 0.25 liters (0.067 gallons) of water per hour.

The combination of flow rate per emitter and spacing determines the total water application per meter (per foot). Therefore, the decision goes hand in hand – the closer the spacing, the lower the flow rate that is required per emitter for the same water application per meter (per foot).

Ultra-low flow drippers

In recent years, drip tapes have been launched with ultra-low flow rate drippers. These new drippers can emit very small volumes of water with flow rates as low as 0.25 liters (0.067 gallons) per hour.

The use of ultra-low flow drippers enables longer irrigation durations, agronomic benefits, while minimizing leaching of valuable water and fertilizers.


Low flow drippers have many benefits. However, do keep in mind that in general, the lower the flow of the dripper, the higher the risk of clogging. Lower flow drippers often require greater filtration protection.

A note about nominal flow-rates

For non-PC drippers, a nominal flow rate is published, which is the flow-rate at a specific pressure. As discussed earlier in the non-PC vs PC section, non-PC drippers have a different flow rate dependent on pressure. Therefore, you need to know what pressure the flow rate was calculated at to determine the nominal flow.

In Rivulis, non-PC drip line flow rates are calculated at 1 bar (14.5 psi) pressure at the dripper.
Note: In the USA, thin-wall drip line flow rates are calculated at 0.7 bar (10 psi) pressure. For PC drip lines, the pressure is irrelevant as the dripper is designed to emit the same volume of water, regardless of pressure (within its operational pressure range).

Drip tape flow rates are generally calculated at 0.55 bar (8 psi) pressure, although some publish flow rates at 0.7 bar (10 PSI), so make sure you check apples–apples. See the next section.

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