Guide · Drip emitters
Pressure-compensating vs non-PC drip emitters: what the ratings and studies say
How PC and non-PC drip emitters respond to pressure, the ranges DIG lists, and what six studies found, each with its own design and limits.
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Picks that fit
- Raindrip PC8050B 2 GPH pressure-compensating dripper (50‑pack)Check price on Amazon
- Raindrip PC8010B 2 GPH pressure-compensating dripper (10‑pack)Check price on Amazon
- Rain Bird SW10‑30PS 1.0 GPH pressure-compensating spot watering emitter (30‑pack)Check price on Amazon
Short answer
A pressure-compensating (PC) emitter holds its rated flow within a stated pressure range; a non-PC emitter's flow changes with pressure. Below that range, a PC emitter behaves like a plain orifice, so the range printed on the maker's page matters more than the PC label. Studies support PC emitters on some measures, but each study had its own design.
Picks that fitAll picks and how to choose
- Raindrip PC8050B 2 GPH pressure-compensating dripper (50‑pack)Check price on Amazon
- Raindrip PC8010B 2 GPH pressure-compensating dripper (10‑pack)Check price on Amazon
- Rain Bird SW10‑30PS 1.0 GPH pressure-compensating spot watering emitter (30‑pack)Check price on Amazon
What the two types do
A non-PC emitter is a fixed passage. More pressure pushes more water through it. DIG's inline emitters are rated 0.5 and 1 GPH at 15 psi, and DIG says their flow depends on the inlet pressure.[1] DIG's flow table for its standard button emitters also rises with pressure.[2]
A PC emitter has a part that reacts to pressure and keeps the flow close to its rating. It only does that inside its compensation range.
Maker ranges side by side
| Emitter | Type | Pressure range the maker lists |
|---|---|---|
| DIG PC button | PC | Compensates 7.25-58 PSI |
| DIG PC dripper on stake | PC | 10-40 PSI (the page also says 15-40 PSI) |
| DIG standard button | Non-PC | 15-25 PSI |
| DIG inline | Non-PC | 5-25 psi; flow changes with pressure |
DIG lists its PC button emitters as compensating between 7.25 and 58 PSI.[3] It lists a 10 to 40 PSI range for its PC dripper on stake, though a feature line on the same page says flow is constant from 15 to 40 PSI.[4] Its standard buttons are rated 15 to 25 PSI.[2] Its inline emitters run from 5 to 25 psi and suit low-pressure gravity-feed systems, DIG says.[1]
When a maker's page disagrees with itself, plan for the narrower number.
What the studies found
Each study below had its own design, products and pressures. None of them ranks today's products, and they cannot be ranked against one another.
- 2019, Agricultural Water Management. A lab study of four drip laterals over a wider pressure range than typical field use, plus one field unit.[5] Its abstract describes PC emitters as giving constant flow above the lower limit of their compensating range and orifice-type flow below it.[5]
- 2004, Harran Plain, Turkey. Nine in-line emitter lines from four makers. Only one of seven non-compensating types, and both compensating types, came within plus or minus 10% of the rated flow.[6] Manufacturing variation was rated unacceptable for the non-compensating emitters and excellent for the compensating ones under ASAE criteria.[6] It is a regional sample from 2004.
- 2026, Irrigation Science. A lab study of six commercial emitters (four PC, two turbulent-flow) at three water temperatures and 50 to 400 kPa.[7] Water temperature changed discharge, with signs of weaker compensation at higher temperature; the PC response varied by model.[7] This was lab work only.
- 2020, clogging. Four types of PC button emitters ran for 980 hours, and three of the four showed satisfactory clogging resistance.[8]
- 2019, Water. A field study compared prototype low-pressure PC online emitters with commercial emitters on nine farms in Morocco and Jordan over one season.[9] Its abstract reports lower uniformity for the prototypes than for the commercial emitters.[9]
- 2013, Journal of Irrigation and Drainage Engineering. A statistical comparison of one PC and one non-PC emitter product at low pressure.[10] We could not read its results directly, so we report only its design.
Do PC emitters work at low pressure?
Only down to the bottom of their range. The 2019 abstract is plain about it: below the lower limit, a PC emitter acts like an orifice.[5] If your supply is low, compare its pressure with the bottom of the range before you pay for PC. Low-pressure gravity feed is the case DIG names for its non-PC inline emitters.[1]
Slopes and long runs
No source we found gives a slope rule for choosing PC emitters. What the ratings do say: a PC emitter holds its flow only while the pressure at that emitter stays inside its range. If a slope or a long run pushes pressure outside the range, the label stops helping.
Uneven watering has many causes
PC is one lever, not the only one. Utah State University Extension lists pressure variation, manufacturing variation, spacing, disrepair, clogging, weather, irrigation duration and soil infiltration as common causes of uneven irrigation.[11] Check the filter, the pressure and the layout before you swap every emitter.
Adjustable is not PC
An adjustable dripper or bubbler lets you turn the flow up or down. That is a different feature. DIG's adjustable mini-bubbler adjusts from full flow to shut-off, and DIG's page does not call it pressure-compensating.[12] See micro-sprays, jets and bubblers.
PC emitters that fit this decision
Picks that fit7 products
All seven are sold as pressure-compensating. Choose by flow: DIG PC button 2 GPH (bag of 100) or 4 GPH (B224B 10-pack), both rated by DIG to compensate between 7.25 and 58 PSI; Raindrip PC8050B (50-pack) or PC8010B (10-pack) at 2 GPH, or PC4010B at 1 GPH (Raindrip states no range for PC8010B or PC4010B); Rain Bird SW10-30PS at 1.0 GPH or SW20-30PS at 2.0 GPH, both 15 to 50 PSI.
More on choosing
Check each maker's range against your pressure.
2 GPH pressure-compensating button
4 GPH pressure-compensating button
Raindrip PC8050B 2 GPH pressure-compensating dripper (50‑pack)
2 GPH pressure-compensating dripper, 10-pack
Raindrip PC8010B 2 GPH pressure-compensating dripper (10‑pack)
1 GPH self-piercing spot emitter
Rain Bird SW10‑30PS 1.0 GPH pressure-compensating spot watering emitter (30‑pack)
2 GPH self-piercing spot emitter
Rain Bird SW20‑30PS 2.0 GPH pressure-compensating spot watering emitter (30‑pack)
Raindrip PC4010B 1 GPH pressure-compensating dripper (10‑pack)
On Amazon, check that "Ships from" and "Sold by" show Amazon.com or the brand before you order.[13]
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Questions
Are pressure-compensating emitters worth it?
They hold their rated flow only inside their stated range. A 2004 study found both compensating types within plus or minus 10% of rated flow but only one of seven non-compensating types; it was a regional sample, not a ranking of today's products.[6]
Do PC emitters work at low pressure?
Only down to the bottom of their range. A 2019 study's abstract describes PC emitters as giving orifice-type flow below the lower limit of their compensating range.[5]
Do I need PC emitters on a slope?
No source we found gives a slope rule. A PC emitter holds its flow only while the pressure at that emitter stays inside the range its maker lists, such as 7.25 to 58 PSI for DIG's PC buttons.[3]
Why is my drip watering uneven?
Utah State University Extension lists eight common causes: pressure variation, manufacturing variation, spacing, disrepair, clogging, weather, irrigation duration and soil infiltration. Check filters and pressure first.[11]
Is an adjustable dripper pressure-compensating?
Not by default. DIG's adjustable mini-bubbler turns from full flow to shut-off, and DIG does not call it pressure-compensating.[12]