How to Adjust Sprinkler Heads (Rotors and Sprays)

Most sprinkler problems in a lawn come down to three settings on each head: the arc (how far it turns or how wide it sprays), the radius (how far the water throws) and the flow or alignment. Rotors are adjusted with a small key or flat screwdriver at the top of the nozzle turret; spray heads are adjusted by turning the nozzle collar and a radius screw on top of the nozzle. Get these right head by head and you stop watering the street, eliminate the brown crescents between heads and use less water doing it. This guide covers how to adjust Rain Bird, Hunter and similar rotor and spray heads, and how to check your work.

In this guide

1. Tools You Need
2. Step 1: Identify Your Sprinkler Heads
3. Step 2: Clean and Straighten Before You Adjust
4. Step 3: Adjusting Rotor Heads
5. Step 4: Adjusting Spray Heads
6. Step 5: Aim for Head-to-Head Coverage
7. Fixing Common Problems
8. Step 6: Check Your Work With a Catch-Can Test
9. When to Adjust Your Sprinklers
10. Frequently Asked Questions

Tools You Need

• The manufacturer’s adjustment key (Hunter and Rain Bird both make inexpensive rotor tools) or a small flat-blade screwdriver.
• A pull-up tool or pliers wrapped in tape to lift spray head risers without running the zone.
• A few flags or stakes to mark heads and problem areas.
• Several straight-sided cans or catch cups for testing.
• A towel and a tolerance for getting wet: many adjustments are easiest with the zone running.

Step 1: Identify Your Sprinkler Heads

Turn on one zone from the controller and watch. Rotor heads shoot one or more streams that slowly turn back and forth across an arc; they typically cover larger areas, often around 15 to 50 feet of radius depending on the model and nozzle. Spray heads pop up and spray a continuous fan of water over a smaller area, commonly up to about 15 feet. Rotary nozzles (such as MP Rotator and Rain Bird R-VAN types) screw onto spray bodies but put out multiple rotating streams; they adjust like a cross between the two. If you are not sure what you have, our overview of types of lawn sprinklers shows each one.

Look at the cap or nozzle for the brand and model. Hunter rotors (PGP, PGJ, I-20) and Rain Bird rotors (3500, 5000 series) are the most common in residential systems, and both publish adjustment instructions for each model online. The general method is the same across brands.

Step 2: Clean and Straighten Before You Adjust

Adjusting a dirty or tilted head is a waste of time. Before touching arc or radius:

• Clear grass and soil from around the head so it pops up fully and retracts.
• Check that the head is vertical and the top sits at or just above soil level. A tilted head sprays into the ground on one side and over the target on the other. Dig around it and straighten it.
• Unscrew the nozzle or cap and rinse the filter screen if the spray is weak, uneven or sputtering.
• Replace cracked caps, broken nozzles and heads that stick up.

Step 3: Adjusting Rotor Heads

Find the fixed edge

Rotors have one fixed edge of their arc and one adjustable edge. Which side is fixed depends on brand and model, so check the instructions or find it by hand: with the zone off, pull up the turret and gently turn it to one stop and then the other. The fixed edge is the stop that stays in place when you change the arc. On Hunter PGP-style rotors, for example, the left edge is the fixed one.

Set the fixed edge

1. Turn the turret by hand to the fixed stop.
2. Rotate the whole head body or riser in the ground (or the internal assembly, depending on design) until the stream at that stop lines up with the edge you want, such as the sidewalk, driveway or bed edge.
3. On many rotors, you can do this with the zone running by turning the turret to the fixed stop and twisting the case until the stream sits exactly on the edge.

Set the arc

Insert the key or screwdriver into the arc adjustment socket on top of the turret, usually marked with a plus and minus or with arrows. Turning one way increases the arc and the other way decreases it; the direction is marked on the cap. Most residential rotors adjust from about 40 to 50 degrees up to 360 degrees. Make small changes, a quarter turn at a time, then let the rotor complete a cycle to see where it reverses. For corners, you want about 90 degrees; along a straight edge, 180 degrees; in the middle of the lawn, full circle.

Adjust the radius

The radius screw sits on top of the turret above the nozzle. Turning it clockwise lowers the screw into the stream, which breaks up the water and shortens the throw. Most rotors allow a reduction of about 25 percent this way. Do not screw it in further to force a bigger reduction; you will get a distorted, uneven pattern. If you need a significantly shorter throw, install a smaller nozzle from the nozzle rack that comes with many rotors. Remember that changing nozzles changes the flow rate, which affects how much water that head puts down compared with its neighbors.

Match nozzles for even watering

A full-circle rotor covers four times the area of a quarter-circle rotor in the same time. To put down the same depth of water, a full-circle head needs a larger nozzle than a half-circle head, which needs a larger one than a quarter-circle head. Rotor manufacturers publish nozzle charts for this. If your corners are soggy and the middle of the lawn is dry, mismatched nozzles are a likely cause.

Step 4: Adjusting Spray Heads

Fixed-arc nozzles

Many spray nozzles have a fixed pattern such as quarter, half or full circle, often marked Q, H and F, or with a degree number. You cannot change the arc on these; you can only aim them. Pull up the riser (by hand, with a pull-up tool or with the zone running) and turn the whole riser stem until the pattern lines up with the edges you want. If the pattern is wrong, swap the nozzle for the correct shape.

Variable-arc nozzles

Variable-arc (often labeled VAN) nozzles adjust from nearly closed to full circle. Hold the riser so it does not spin, then turn the collar or the top of the nozzle to open or close the arc. Line up the fixed side first by turning the riser, then open the arc until it reaches the other edge. These are ideal for odd angles along curved beds and walks.

Radius on spray nozzles

The small screw in the center of the nozzle top adjusts radius. Turning it clockwise reduces the throw, generally by up to about 25 percent. Pull back a head that is soaking the sidewalk, but if you need it to reach much less far, use a shorter-radius nozzle. A spray that throws a mist or fog rather than droplets usually indicates pressure that is too high; pressure-regulating spray bodies or nozzles fix that and also reduce wind drift.

Rotary nozzles

Rotary nozzles adjust arc by turning an outer ring or collar, often with the nozzle popped up and running, and adjust radius with a center screw, using the maker’s tool. Because they apply water slowly, they are excellent on slopes and clay, but they need longer run times than standard sprays, so keep them on their own zone.

Step 5: Aim for Head-to-Head Coverage

Irrigation systems are designed so each head throws water all the way to the neighboring heads. That overlap evens out the pattern, because every sprinkler puts down more water near the head and less at the edge of its throw. If you shorten a radius so much that heads no longer reach each other, you create dry rings between them. Before reducing any radius, check whether the spray reaches the next head; if it does not, the fix may be a larger nozzle, cleaning, or more pressure rather than less.

Fixing Common Problems

Problem	Likely cause	Adjustment
Watering the street or sidewalk	Arc too wide, fixed edge misaligned, radius too long	Realign fixed edge, reduce arc, reduce radius up to 25% or change nozzle
Dry crescents between heads	No head-to-head overlap, clogged nozzle, low pressure	Clean nozzle and screen, increase radius, check pressure
Soggy corners, dry middle	Mismatched nozzles on rotors	Install correctly sized nozzles per manufacturer chart
Rotor stuck in one spot	Debris, worn gear drive	Flush the head; replace the internal assembly or head if it still sticks
Misting and drift	Pressure too high for spray nozzles	Use pressure-regulating bodies or nozzles
Spraying into shrubs	Head too low or blocked by growth	Trim plants, raise head or install a taller riser

If heads will not pop up, a whole zone is weak or a valve will not shut off, the issue is upstream of the heads. Our sprinkler system troubleshooting guide walks through valves, leaks and controller problems.

Step 6: Check Your Work With a Catch-Can Test

1. Place six to ten straight-sided cans (tuna cans work) in a grid across one zone, including near heads and midway between them.
2. Run the zone for 15 minutes.
3. Measure the water depth in each can with a ruler.
4. Look for big differences. Cans with much less water mark dry spots that need better coverage; very full cans near certain heads suggest oversized nozzles.
5. Multiply the average depth by four to estimate inches per hour, then use that to set run times.

Most lawns need roughly 1 inch of water per week from rain and irrigation combined, more in hot, dry weather and on sandy soil. With your inches-per-hour figure, you can program accurate run times; our guide on how to set a sprinkler timer covers scheduling and cycle-and-soak settings.

When to Adjust Your Sprinklers

Walk each zone at least at spring startup, midsummer and before fall. Heads get knocked out of alignment by mowers, edgers and foot traffic, and plants grow into spray patterns. Spring is the best time for a full check, as part of a spring sprinkler system startup. Even watering is one of the biggest factors in an even lawn, alongside mowing height and feeding; our lawn care guide covers the rest.