How many sprinkler heads per zone, and how many zones you need

Short answer

Divide the flow your water supply delivers by the flow of one head’s nozzle at your pressure, and round down. In Rain Bird’s own example, 10 gallons a minute and rotors using about 3.1 gpm each gives three heads per zone. Keep rotors, spray heads and drip on separate zones, add zones until every area is covered, then buy a controller with at least that many stations.

Time: an evening with a sketch of your yard and a calculator
Difficulty: Moderate: simple arithmetic, but it decides the whole layout
Rough cost: nothing beyond the gauge and bucket you measured with; the zone count then sets how big a controller you buy

A zone is the group of heads that one valve, or one outlet of a hose timer, turns on together. The heads share whatever the supply can give, so put too many on one zone and they all fall short. The zone count then decides the controller, so do this sum before you buy one. Every model we track is in our sprinkler controller comparison.

What you’ll need

Your static pressure and bucket-test flow. If you haven’t taken them yet, our guide to measuring water pressure and flow takes about 15 minutes.
A rough sketch of the yard with measurements, beds, trees, the house, walks and driveway, as Rain Bird’s planning guide suggests. Graph paper helps.
The performance chart for the heads you plan to use. Rain Bird says it is printed on or inside the box, and on the maker’s support pages.
A calculator and a pencil.

Step 1: Start from the flow you can use

Your bucket-test result in gallons per minute (gpm) is the ceiling for any one zone. It is measured at an open faucet, so it is the most your supply can give, not what a zone gets after pipe, fittings and slope have taken their share. Rain Bird’s Landscape Irrigation Design Manual also limits flow by what the water meter and service line can safely pass and designs to the lowest figure, so on a full system planned from the main line those limits may sit below your bucket result.

On a hose faucet, the kit maker has done this sum for you. Rain Bird’s 32ETI is one zone of six rotors built around a faucet that gives at least 6 gpm, and Rain Bird says it isn’t designed for extra heads, which can stop them turning or popping up. Orbit’s 50021 splits twelve sprinklers into two zones, run in turn from a two-outlet timer. Follow the kit’s layout rather than adding to it.

Step 2: Split the yard by what each area needs

Before counting heads, divide the sketch into areas that need the same watering. Rain Bird’s homeowner installation guide separates zones by landscape type, sun exposure, slope and pressure limits, and its planning guide adds that shrubs, flowers and grass need different amounts of water, which separate zones let you schedule. Three rules follow from that:

Never mix rotors and spray heads on one zone. Rain Bird’s guide says mixed head types water unevenly and unbalance the pressure. Its design manual explains why: fan sprays put down roughly 1 to 4 inches of water an hour, while rotors spread theirs over a bigger area and apply it much more slowly, so on a shared zone you overwater one area to water the other.
Keep drip on its own zones. Drip flows are measured in gallons per hour, not per minute, and both Rain Bird’s manual and Colorado State University Extension say drip and sprinklers never share a zone. CSU also puts micro-sprays on a separate zone from other drip parts because they use far more water.
Keep lawn and beds apart, and consider splitting sunny and shaded lawn. Rain Bird’s design manual does this in its worked example, where a front lawn area that gets more afternoon shade has its own valve.

The manual uses spray heads (about 5 to 22 feet of throw) for small areas, strips and borders, and rotors (from about 20 feet up) for open lawn. Matched-precipitation spray nozzles are sized so a full circle uses twice the water of a half, and a half twice a quarter, so different arcs can share a zone.

Step 3: Look up each head’s flow at your pressure

A nozzle uses more water at higher pressure, so read its flow from the chart at the pressure your heads will see, which is below your static reading. Some figures from the makers’ own charts show how much they vary:

Rain Bird 32ETI kit rotors: 0.75 gpm nozzles fitted, with spare 1.0 and 1.5 gpm nozzles that throw farther but need at least 8 gpm from the faucet.
A standalone Rain Bird 32SA rotor: ships with a 3.0 nozzle using about 2.2 to 3.3 gpm between 25 and 55 psi, several times the kit nozzle, so a replacement head on a kit may need a smaller nozzle.
Rain Bird 5000 Series rotor, 3.0 nozzle: 3.11 gpm at 35 psi.
Fixed spray nozzles: an example chart in Rain Bird’s design manual lists a 15-foot spray nozzle at 30 psi at 3.7 gpm for a full circle, 1.85 for a half and 0.93 for a quarter.
Drip emitters: commonly 0.5, 1 or 2 gallons per hour (gph); 60 gph equals 1 gpm.

These are examples: use the chart for the exact nozzles you buy.

Step 4: Divide and round down

For a zone of identical heads, divide your flow by one head’s flow and round down. Rain Bird’s example: 10 gpm ÷ 3.11 gpm = 3.2, so three rotors per zone. Orbit gives the same rule in its help center: the nozzle flows on a zone must add up to no more than the supply, so 12 gpm runs four heads with 3 gpm nozzles before performance drops.

When arcs differ, add each head’s flow instead. With 10 gpm and the spray chart above, four quarter circles (3.72 gpm) and three half circles (5.55 gpm) total 9.27 gpm and fit. Add a full circle (3.7 gpm) and the total reaches 12.97 gpm: that is two zones.

Don’t plan a zone to the last tenth of a gallon. Rain Bird’s homeowner design service caps each zone’s total demand to keep water speeds safe and prevent water hammer, and its own kit leaves room: six 32ETI rotors at 0.75 gpm use 4.5 gpm against a 6 gpm minimum, about three-quarters. For drip, CSU makes the margin a rule: a zone should use no more than 75% of the bucket-test flow, and 1/2-inch drip tubing carries only about 200 gph per zone (3/4-inch about 480). Add the emitters up in gph: fifty 2 gph emitters are 100 gph, in CSU’s example.

Step 5: Count the zones (a worked example)

Here is one yard worked through, using the chart figures above. The house has a main-line supply that fills a 5-gallon bucket in 30 seconds, so 10 gpm is the most any zone may use.

Open back lawn: rotors. Nine rotors, each with a nozzle the chart lists at 3.11 gpm, need 28 gpm in all. Three per zone (9.33 gpm, as in Rain Bird’s own example) gives 3 zones.
Front lawn: sprays. It is too narrow for rotors. Four quarter circles, four half circles and one full circle need 14.8 gpm, so it splits in two: the sunny side (four quarters and two halves, 7.42 gpm) and the side under a shade tree (two halves and the full circle, 7.4 gpm). That is 2 zones.
Shrub and flower beds along the house: drip. Thirty shrubs on two 1 gph emitters each use 60 gph, which is 1 gpm. 1 zone.
Vegetable bed: drip, on its own because vegetables and shrubs need different amounts of water. 1 zone.

That makes seven zones. The two drip zones use a fraction of the supply, but they still get their own valves, because their run times differ so much from the lawn’s.

Safety: when you mark the plan out in the yard, request a locate before any trench: contact 811 in the US or use Click Before You Dig in Canada, wait until every utility has marked its lines, and dig around the marks, not on them. In Alberta, Saskatchewan and Manitoba, the one-call services say customer-owned lines such as an existing sprinkler system aren’t marked, so ask about a private locator.

Step 6: Size the controller from the zone count

Each zone needs its own station on the controller; Rain Bird’s design manual sizes the controller from the valve count in exactly this way. Seven zones need at least seven stations, and if you might add a bed or a drip line later, a spare station or two saves replacing the controller. Controllers come in two kinds:

Fixed sizes. The Rachio 3 we list is the 8-zone model, and Rachio also makes 4, 6, 12 and 16-zone versions. The Orbit B-hyve 6-zone has a 12-station sibling covered by the same manual. For seven zones, an 8-zone Rachio leaves one spare and a 6-zone B-hyve is too small. Choose the size up front: you can’t add stations later.
Modular. Rain Bird’s ESP-Me3 starts with 4 stations and takes plug-in 3- and 6-station modules up to 22. Rain Bird says to fit 6-station modules first, so seven zones means the base plus one 6-station module: 10 stations, with two bays free.

Weighing the two most compared smart models? Read Rachio 3 vs Orbit B-hyve, or see our picks of the best smart sprinkler controllers. On a hose faucet, zones are timer outlets instead: a multi-outlet timer from our hose timer comparison runs each outlet as a zone.

Safety: these controllers run 24-volt valves from a transformer, but the supply side is household power. Orbit asks for a GFCI outlet outdoors and advises an electrician for hardwiring; Rain Bird says wiring must follow local codes, some of which require a licensed electrician; Rachio says never to hardwire the controller itself. Switch off the breaker before any hardwired work, and if you’re unsure, hire an electrician.

When the system is in, do as Rain Bird’s installation guide says: write down which station runs which zone and keep the list by the controller.

Troubleshooting

Every head on one zone falls short or won’t pop up: the zone asks for more than the supply gives. Split it, or fit smaller nozzles, and recheck the sum.
Part of a zone is soggy while another part is dry: look for mixed head types or areas with different sun or plants on the same zone, and give them separate zones.

How we put this guide together

Took the heads-per-zone method and its examples from Rain Bird’s zone-sizing page and Orbit’s help center.
Took the zoning rules from Rain Bird’s homeowner installation guide and Landscape Irrigation Design Manual, and the drip limits from Colorado State University Extension.
Took nozzle flows from Rain Bird’s published charts and kit guides, and station counts from each controller’s manual or spec sheet.

What we don’t do: design or install systems, or test heads and controllers in a yard. The worked example is arithmetic on published figures, not a measured system.

Our full method

Heads and zones questions

Can I put rotors and spray heads on the same zone?

No. Rain Bird’s homeowner guide says not to mix head types on one zone, because the watering turns uneven. Spray heads put water down much faster than rotors, so whatever run time suits one leaves the other area too wet or too dry. Give each type its own zone, even if one of them ends up with only a few heads.

Can drip and sprinklers share a zone?

No. Drip runs in gallons per hour and needs long, gentle run times, while sprinklers run in gallons per minute, and both Rain Bird’s design manual and Colorado State University Extension keep them on separate zones. CSU notes that if you convert one spray head on a zone to drip, the other heads on that zone have to be capped.

Can I wire two valves to one controller station?

It depends on the controller. Orbit’s B-hyve manual allows only one valve per station. Rain Bird’s ESP-Me3 can power two valves per station, but they always open together, so they behave as one zone and their combined flow must still fit your supply. If you need more zones, a bigger controller or an extra module is the cleaner fix.

How many heads can a hose-faucet sprinkler kit run?

As many as the maker designed it for, and no more. Rain Bird’s 32ETI runs six rotors as one zone, with no more than three on any one length of tubing, and isn’t designed for extra heads. Orbit’s 50021 splits twelve heads into two zones from a two-outlet timer. Both assume the faucet meets their minimum pressure and flow.

Is it worth buying a controller with spare stations?

Usually, if there’s any chance you’ll add a bed, a drip line or a new lawn area. A fixed-size controller can’t grow, so a full one has to be replaced. Sizes vary by brand: the Rachio 3 comes in 4 to 16 zones and the B-hyve indoor/outdoor in 6 or 12, while the ESP-Me3 adds modules up to 22 stations.