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Impact Sprinkler Troubleshooting Guide

If your impact sprinkler isn’t rotating or spraying properly, don’t worry—most issues are easy to diagnose and fix. Use this guide to identify common problems and get your system back up and running.

Before You Start

  • Confirm that your sprinkler is installed according to the manufacturer’s instructions.
  • Make sure all valves are fully open and there are no obvious leaks in the system.
  • Check that the nozzle size and number of sprinklers match your water supply capacity.

Issue 1: Sprinkler Not Working Initially

Step 1: Check Water Pressure and Flow

The most common reason an impact sprinkler will not start working is insufficient pressure or flow.

  • Verify your pump’s capability using the pump curve from the manufacturer.
  • If you don’t have a pump curve:
    • Measure system pressure with a pressure gauge.
    • Perform a flow test to estimate gallons per minute (GPM).
  • Compare your actual pressure and flow to the sprinkler’s performance chart to confirm it meets minimum requirements.

Step 2: Inspect for Shipping or Handling Damage

If pressure and flow are adequate, make sure the sprinkler itself is in good condition:

  • Verify the sprinkler turns freely by hand.
  • Look for visible damage, especially:
    • Bent impact arm or arm that does not swing smoothly.
    • Cracked or broken parts on the body or bearing assembly.

Step 3: Check for Debris and Clogging

New installations often have debris in the lines (sand, tape, small plastic pieces, etc.). This can clog the nozzle or stop the rotation.

  • Flush the lines before and after installing sprinklers:
    • Remove the sprinkler head from the riser.
    • Open the valve and let water run briefly to flush out debris.
  • Inspect the nozzle opening and remove any debris blocking the orifice.
  • If the sprinkler still won’t rotate:
    • Debris may be inside the washers or lower bearing assembly.
    • Disassemble the lower bearing assembly (if you are comfortable doing so) and clean the washers and internal surfaces.

Step 4: Only the Last Sprinklers Aren’t Working

If sprinklers nearest the water source work, but the last sprinklers in the line do not, this usually indicates:

  • You are running too many sprinklers for your water supply to support, or
  • There is too much pressure loss over the length of the pipeline.

Possible solutions:

  • Reduce the number of sprinklers running at one time (create smaller zones).
  • Use a larger supply line to reduce friction loss.
  • Shorten the length of each run where possible.

Issue 2: Sprinkler Worked for a While, Then Stopped

Step 1: Check for Hard Water and Dirt Buildup

If a sprinkler was working and gradually stopped rotating or became sluggish, the most common cause is dirt or mineral buildup, especially from hard water.

  • Look for white or chalky stains on the head or lower bearing assembly (signs of hard water deposits).
  • Over time, deposits and fine debris increase friction so the sprinkler requires more force to turn than the pump can provide.

Recommended actions:

  • Disassemble and clean the bearing washers and moving parts according to the manufacturer’s instructions.
  • Replace the washers or internal parts if they are excessively worn or damaged.
  • Increase operating pressure slightly if your system and sprinkler specifications allow it.

Cleaning frequency depends on water quality:

  • Some users clean sprinklers once per season.
  • Customers with very hard water may need to clean as often as weekly.
  • If cleaning is required too frequently, consider installing a filter or hard water treatment solution.

Often, you’ll first notice sprinklers at the end of the line stop rotating, since they have the lowest pressure.

Step 2: Inspect for Physical Damage

Another common reason for a previously working sprinkler to fail is physical damage.

  • Sprinkler stands can fall over if they are not secured properly.
  • Animals, vehicles, or equipment can knock over or strike the sprinkler.
  • The most common damaged part is the impact arm, which may bend and prevent proper motion or spray pattern.

If you suspect damage:

  • Inspect the impact arm and all moving parts for bends, cracks, or misalignment.
  • Replace damaged parts as needed.

If you need replacement parts for your sprinkler, please contact our customer service team at Support@irrigationking.com.

Preventive Maintenance Tips

  • Flush lines before installing new sprinklers or after repairs.
  • Install appropriate filters if you have dirty water or frequent clogging issues.
  • Periodically inspect and clean sprinklers, especially in hard water areas.
  • Secure sprinkler stands and risers to reduce the risk of damage from tipping or impact.

With regular inspection and simple maintenance, most impact sprinkler issues can be resolved quickly, helping your irrigation system run smoothly and efficiently.