Sprinkler Nozzle Adjustment: How to Set Arc & Radius (2026)

Is your sprinkler system watering the driveway more than the lawn? Are you noticing frustrating dry brown spots or soggy puddles in your grass? These common problems indicate your system needs a tune-up. The good news is that a simple sprinkler nozzle adjustment—which involves changing the spray distance (radius) with a screw and setting the spray pattern (arc) with a twist of the nozzle or a key—can solve most of these issues. This guide will help you save water and grow a healthier lawn with smart irrigation systems.

It’s a surprising fact, but studies estimate that 30 to 60 percent of residential irrigation water is wasted due to issues like overspray, leaks, and poor adjustments. By fine tuning your sprinkler heads, you can put that water back where it belongs. This guide will walk you through everything you need to know about sprinkler nozzle adjustment, from simple screw turns to setting complex rotor patterns.

The Basics: Adjusting Spray Distance and Pattern

Before diving into specific sprinkler types, let’s cover the two most fundamental adjustments you can make: changing how far the water sprays and what pattern it covers.

Adjusting Spray Distance (Radius)

Nearly every sprinkler head, whether it’s a small pop up or a large rotor, has a way to change its spray distance, also known as the radius.

For most pop up spray heads, this is done with a small center screw adjustment. You’ll find a screw right on top of the nozzle.

• To decrease the distance: Use a small flathead screwdriver to turn the screw clockwise (tightening it). This action deflects the water stream, causing it to fall shorter. This simple turn can reduce the spray radius by up to 25 percent.

• To increase the distance: Turn the screw counterclockwise (loosening it) to allow the water to flow freely, maximizing its reach.

Be careful not to tighten the screw too much, as it can disrupt the spray pattern. This adjustment is best for minor tweaks. If you need a significant reduction in distance, changing to a smaller nozzle or full sprinkler head replacement is the better solution.

Adjusting the Spray Pattern (Arc)

For pop up spray heads with adjustable nozzles (often called variable arc nozzles or VANs), you can also change the angle of the spray pattern. This is incredibly useful for odd shaped areas of your lawn.

First, you need to align one edge of the spray. You can usually do this by gently twisting the pop up stem itself to rotate the nozzle. Once one side is set, you can twist the top ring of the nozzle to change the arc. On many models, turning it counter clockwise increases the arc, while turning it clockwise makes the pattern narrower.

Mastering Rotor Sprinkler Nozzle Adjustment

Rotor heads, the kind that rotate back and forth, require a few more specific steps for a proper sprinkler nozzle adjustment. They have two main settings you need to get right: the arc (the left and right stops) and the radius (the throw distance).

Setting the Edges: Left and Right Stops

Before you can set the arc, you must define the boundaries. This is called left right edge setting. Rotors have one fixed edge and one adjustable edge. For many brands like Rain Bird, the left side is fixed, while for brands like Hunter, the right side is the fixed stop.

1. Find the Fixed Stop: With the water off, manually turn the sprinkler turret all the way in one direction until it stops, then turn it back the other way until it stops again. This helps you identify the current fixed edge.

2. Align the Fixed Edge: Without digging up the whole sprinkler, you can often unscrew the cap and lift the entire internal assembly, then reposition it so the fixed edge points exactly where you want the watering to stop (like the edge of a sidewalk). Then you simply screw the cap back on.

3. Adjust the Arc: Once the fixed side is aimed correctly, you can adjust the other side by changing the arc.

Adjusting the Rotor Arc (Coverage Angle)

After setting your fixed edge, you can now tell the sprinkler how far to rotate. For this rotor head arc adjustment, you’ll typically use a special key or a small screwdriver. You insert the tool into the arc adjustment slot on top of the rotor.

Turning the tool in one direction will increase the arc, while turning it the other way will decrease it. On many rotors, a full 360 degree turn of the tool changes the arc by 90 degrees. Most rotors allow for an arc between 40 and 360 degrees. You’ll often hear a clicking sound when you’ve reached the minimum or maximum setting.

Adjusting Rotor Radius (Throw Distance)

Just like spray heads, rotors have a way to reduce their throwing distance. The rotor radius adjustment is controlled by a screw, often called the radius reduction screw, located on top of the nozzle. Tightening this screw (clockwise) interrupts the water stream, shortening the throw. This can typically reduce the range by about 20 to 25 percent. For bigger changes in distance, you should swap out the nozzle for a smaller or larger one.

Brand Specific Sprinkler Adjustments

While the principles are similar, some popular brands have unique tools and methods.

Hunter Rotor Adjustment with a Key

Hunter rotors, like the popular PGP series, are designed to be adjusted with a special plastic and steel Hunter adjustment key. This multipurpose tool is essential for any Hunter rotor adjustment with key.

• Arc: Insert the plastic end of the key into the arc adjustment socket. With the rotor held at its fixed right stop, turn the key clockwise to increase the arc and counter clockwise to decrease it.

• Radius: Insert the steel hex end of the key into the radius reduction screw and turn it clockwise to reduce the spray distance.

• Nozzle Changes: The key also functions as a pop up stem pull up tool. You can insert it into the lifting socket and turn it to pull up the sprinkler stem, making it easy to change nozzles.

Signature (Nelson) Rotor Click Set Adjustment

If you have an older system, you might encounter Signature or Nelson rotors. A Signature rotor click set adjustment is a bit different. These models use a “Click Set” disk on top to control the pattern. You physically remove and flip the disk from the full circle side to the part circle side, then use adjustable collars to “click” the arc into place.

Troubleshooting and Maintenance Tips

A perfect sprinkler nozzle adjustment can be undone by simple maintenance issues. Here’s how to tackle the most common problems.

Nozzle Cleaning for Debris Clogs

Is a sprinkler head sputtering or spraying an uneven, weak pattern? The most likely culprit is a clog. A tiny piece of dirt or sand can easily block the nozzle or the filter screen beneath it, leading to dry spots in your lawn.

Nozzle cleaning is simple:

1. Unscrew the nozzle from the sprinkler head.

2. Pull out the small filter basket located just below the nozzle.

3. Rinse both the nozzle and the filter under clean water. Use a thin wire to gently poke out any stubborn debris from the nozzle opening.

4. Before reassembling, turn on that sprinkler zone for a few seconds to flush any dirt out of the pipe.

5. Put the clean filter and nozzle back on.

The Critical Role of Water Pressure

Have you adjusted everything perfectly but the spray distance is still too short? The problem might be your water pressure. The effect of water pressure on spray distance is huge.

• Low Pressure: If pressure is too low, the spray will be weak and won’t reach its intended radius. This can be caused by a leak in the line or too many heads on one zone.

• High Pressure: If pressure is too high, water atomizes into a fine mist that blows away and evaporates before it can water your lawn. This “fogging” effect wastes a tremendous amount of water.

Most spray heads perform best around 30 PSI, while rotors are designed for about 45 PSI. If you suspect pressure issues, it may be time to consult a professional sprinkler repair team. The licensed irrigators at M&M Sprinklers can diagnose pressure problems and install regulators to ensure your system runs at peak efficiency.

Preventing Overspray and Tuning Coverage

The ultimate goal of any sprinkler nozzle adjustment is perfect coverage. Overspray prevention and coverage tuning means every head is watering the lawn and only the lawn, with each sprinkler’s spray reaching the next sprinkler head. This is called head to head coverage and it is the key to uniform watering. If your yard’s layout makes this tough, an irrigation system design refresh can help.

Walk through your yard while a zone is running. Look for water hitting sidewalks, fences, or walls. Use the radius and arc adjustments to dial it in perfectly. A few small tweaks can make a massive difference in your water bill and the health of your landscape. For set‑and‑forget scheduling that adapts to weather, consider a Wi‑Fi sprinkler controller.

If you find yourself constantly battling dry spots or overspray, don’t hesitate to get an expert opinion. A professional irrigation system checkup can identify hidden issues and get your system perfectly calibrated. For homeowners in Lubbock and West Texas, M&M Sprinklers offers comprehensive services to keep your lawn green and your water bills down. Property managers and HOAs can see our commercial sprinkler repair guide for maintenance best practices.

Frequently Asked Questions About Sprinkler Nozzle Adjustment

1. How do I adjust the spray distance on my pop up sprinklers? You can typically reduce the spray distance, or radius, by turning the small screw on top of the nozzle clockwise with a flathead screwdriver. This can shorten the throw by up to 25%.

2. How do I change my sprinkler from a full circle to a half circle? For a rotor sprinkler, you’ll need to use its adjustment key or tool to decrease the arc setting from 360 degrees down to 180 degrees. For a pop up spray head, you either need to install a fixed half circle (180°) nozzle or adjust a variable arc nozzle by twisting its top collar.

3. Why is one of my sprinkler heads not spraying as far as the others? This could be caused by a few things. First, check if the nozzle or filter screen is clogged with debris. If it’s clean, you may have low water pressure in that zone, which could be due to a leak in the pipe or too many heads running at once.

4. What tool do I need for a Hunter sprinkler nozzle adjustment? You will need a specific Hunter adjustment key. This tool has a plastic end for adjusting the arc and a steel hex wrench on the other end for adjusting the radius (distance).

5. Can I adjust the direction of a sprinkler without digging it up? Yes. For most pop up spray heads, you can gently twist the extended stem to redirect the nozzle. For rotors, you can often unscrew the main cap and lift out the internal body to reorient its fixed stop without disturbing the case in the ground.

6. How do I stop my sprinklers from watering the sidewalk? This is a classic overspray problem. You can fix it by adjusting both the arc and the radius. First, adjust the arc’s left or right stop to align with the edge of the grass. Then, use the radius reduction screw to shorten the spray distance so the water no longer lands on the pavement.