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WateringTimes

Minutes, matched to your watering days

How long to run your sprinklers

Most watering advice stops at how many days a week. This works out the other half: how many minutes each of those days, from your city's climate for the month you pick, what is planted, and how fast your nozzles put water down. Rates verified August 28, 2026 against manufacturer performance tables, sources at the bottom.

About 42 minutes per watering day, 2 days a week.

How that was worked out

Week's climate demand: 8.6 in for July × 7 ÷ 31 days = 1.942 in

Plants need: 1.942 × 0.8 = 1.554 in this week

Run time: 1.554 ÷ (1.6 in/hr × 0.7) × 60 = 83 min per week

Split: 83 ÷ 2 watering days = 42 min each time

If water runs off the edges before the cycle ends, split each day into shorter back-to-back cycles with a soak break between them. The total minutes stay the same.

Rain is not subtracted here. Skip watering during and after rain, and follow your supplier's rain rule. Point-source drip emitters and Bubblers are not in the list above: no manufacturer publishes an inches-per-hour rate for them, so those zones are watered by volume rather than by a run time against a rate.

The formula, spelled out

week's climate demand = monthly reference evapotranspiration × 7 ÷ days in month

water the plants need = week's demand × plant water rating

run minutes per week = need ÷ (nozzle rate × system evenness) × 60

minutes per watering day = weekly minutes ÷ days you are allowed to water

The climate number comes from the state reference table for 676 California cities, the plant rating from the state plant water classification, and the nozzle rate from the manufacturer tables below. Dividing by system evenness is what stretches the cycle far enough that the driest corner of the zone still gets watered. Distribution uniformity. UC's run-time formula divides by DU; 0.7 is the working default for an average home system. New sprinkler heads on the state ordinance's prescriptive path must document a low-quarter DU of 0.65 or higher (section 492(c)(2)(F)). A catch-can test replaces this default with a measured value.

How fast each nozzle type applies water

Published precipitation rates by device type, inches per hour

The device column stays put while the table scrolls sideways on a narrow screen.

DeviceUsed hereWhat the manufacturer tables print
Pop-up spray heads1.6Rain Bird 12-18 ft nozzle families print 1.58-1.76 in/hr at the 30 psi optimum on square spacing. Across the full 15-30 psi range the same tables print 1.58-3.80 square (short-radius 4/6/8 ft nozzles print 2.79-10.27 square). UC ANR Publication 8044's homeowner catch-can example measured 1.437 in/hr in the field.
Rotor heads0.5Rain Bird 3500 Series operating spec prints 0.37-0.83 in/hr; 5000 Series prints 0.20-1.50 in/hr, with standard-angle nozzle tables at 45 psi clustering 0.24-0.92 square. Hunter PGP Ultra prints 'approximately 0.4 in/hr'.
Rotary nozzles, Hunter MP Rotator0.4Hunter's cutsheet prints 'approximately 0.4 in/hr'; performance tables at the 40 psi optimum print 0.37-0.45 square and 0.42-0.52 triangular across MP1000 to MP3500.
Rotary nozzles, Rain Bird R-VAN0.6R-VAN tech-spec tables print 0.56-0.77 in/hr overall; at the recommended 45 psi they print 0.61-0.64 square, with a 0.77 top on one triangular configuration.
Inline dripline, clay soil setup0.2Table 5 prints 0.17-0.67 in/hr for 0.4 gph across 12-24 in spacings; the clay configuration prints 0.22 down to 0.17.
Inline dripline, loam soil setup0.43Table 5 prints 0.24-0.96 in/hr for 0.6 gph across 12-24 in spacings; the printed 18 in by 18 in example is 0.43.
Inline dripline, sandy soil setup0.96Table 5 prints 0.36-1.44 in/hr for 0.9 gph across 12-24 in spacings; 0.96 at 12 in emitters with 18 in rows, 1.44 at 12 in by 12 in.
Point-source drip emittersnot publishedNo in/hr rate published. Printed flows are 0.5, 1.0 and 2.0 gph, pressure compensating from 15 to 50 psi.
Bubblersnot publishedNo in/hr rate published. Printed flows are 0.25 to 2.0 gpm per bubbler at 1 to 3 ft spacing, 20 to 90 psi for the pressure-compensating series; the adjustable series prints 1.0 to 2.3 gpm at 10 to 60 psi.

Rates assume head-to-head spacing at the recommended operating pressure and exclude system evenness, which the run-time formula applies separately. Point-source emitters and bubblers carry no published rate at all: their output depends on spacing, so those zones are watered by volume instead.

Worked example

A Sacramento lawn in July on ordinary spray heads. July reference evapotranspiration is 8.6 inches for the month, so a week carries 8.6 × 7 ÷ 31 = 1.942 inches of demand. A cool-season lawn rates high water, 0.8, so the grass needs 1.554 inches that week. Spray heads apply about 1.6 inches per hour, and at an evenness of 0.7 the run time is 1.554 ÷ (1.6 × 0.7) × 60 = 83 minutes for the week. Sacramento allows two watering days from March through October, so that is roughly 42 minutes on each of them, best split into shorter cycles if the water starts running off.

Questions people ask

How long should I run my sprinklers?
It depends on four things, and the calculator above puts numbers on all of them: how much water your climate pulls out of the ground this month, what is planted, how fast your nozzles apply water, and how evenly they do it. A lawn on ordinary spray heads in a hot inland July often lands near half an hour per watering day, while the same lawn in a cool coastal month or on rotary nozzles lands somewhere very different.
Why does the answer depend on the nozzle type?
Because nozzles apply water at very different speeds. Pop-up spray heads put down roughly 1.6 inches per hour, rotors and rotary nozzles closer to 0.4 to 0.6. Slower nozzles need proportionally longer run times for the same amount of water, which is why swapping heads without changing the timer usually leaves plants dry.
What is distribution uniformity and why does it stretch the run time?
No sprinkler system wets every square foot equally, so parts of a zone get less than the average. Distribution uniformity is a measure of that evenness, and the run-time formula divides by it, which lengthens the cycle so the driest spots still get enough. The default here is 0.7 for an average home system; a catch-can test replaces it with a measured value.
Should I water the whole time in one go?
Only if the water soaks in. On slopes and heavy clay, sprinklers often apply water faster than the ground absorbs it, and the excess runs into the gutter. The fix is cycle and soak: split the day’s minutes into shorter back-to-back cycles with a break between them. The total run time stays the same, the runoff stops.
Does the calculator account for rain?
No, and that is deliberate: it computes the demand your plants face in a dry week. When it rains, skip the cycle. Most California suppliers also prohibit irrigating during rain and for 48 hours afterward, so the rules and the plants agree on this one.
Why are drip emitters and bubblers missing from the list?
Because no manufacturer publishes an inches-per-hour rate for them. With point-source emitters and bubblers the rate depends entirely on how far apart the devices sit, so an assumed number would be invented rather than sourced. Those zones are watered by volume, meaning gallons per plant, rather than by a run time against a rate.

Related on WateringTimes

Sources

WateringTimes is an informational gardening and landscape reference for California. Watering numbers are estimates computed from public state data. Nothing on this site is regulatory or professional advice of any kind. Check your water supplier’s current rules before relying on any schedule.