Irrigation Diagnostics
How to Troubleshoot Your Sprinkler System
Find the problem before you start replacing parts.
When an irrigation system is not performing correctly, the hardest part is often figuring out what is actually wrong.
A dry area may be caused by a clogged nozzle, poor coverage, low pressure, compacted soil, or improper programming. A soggy area could indicate a broken pipe, a leaking valve, poor drainage, or simply overwatering.
Before replacing parts or increasing run times, take a methodical approach. A few basic tests can help you narrow down the problem, avoid unnecessary repairs, and determine when it is time to call an irrigation professional.
Natural State Horticare does not offer irrigation repair services. However, we do offer Irrigation Optimization for operational systems that need better programming, coverage evaluation, and water management.
First, Physically Check The Soil
Water is VERY important, but getting it right can be tricky.
Programming HAS TO CHANGE WITH THE SEASONS! What works in May isn’t enough for August, and what works in August is too much for October.
Areas that look like they are getting good irrigation coverage often aren’t.
Areas that border two zones, like grass and landscaping, can quickly become overwatered despite the individual zones being programmed correctly.
All irrigation parts are plastic and need to be consistently monitored for damage/wear and tear that could cause issues.
Before adjusting your watering schedule, probe several inches into the ground.
Prob/sample the “bad spot”
Prob/sample a spot that looks significantly healthier.
Compare the samples; if they differ noticeably, aim to recreate the conditions found in the healthier area.
If the soil is already damp, more irrigation may make the problem worse.
If it is a watering issue, all the fertilizer, fungicide, and pesticide in the world won’t help.
Diagnostic Trouble Shooting Step-by-Step Guide
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Start by running each irrigation zone individually from the controller. This should be done EVERY YEAR!
Do not simply turn the system on and walk away. Watch each zone operate for several minutes.
Look for:
Heads that do not rise
Heads spraying in the wrong direction
Weak or uneven spray patterns
Water shooting straight into the air
Water bubbling around a head
Mist instead of defined water droplets
Water spraying onto pavement, fences, or buildings
Areas receiving little or no coverage
Water pooling around valve boxes
Zones that will not turn on
Zones that will not shut off
Mark damaged or questionable areas with small flags so you can find them after the system is turned off.
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Many irrigation problems are programming problems, not mechanical failures.
Review the following settings:
Date and Time
Power interruptions can reset some controllers. An incorrect date or time may cause the system to run at unexpected hours or on the wrong days.
Check the Programming
Follow our FREE Programming Guide.Rain Delay and Sensors
Check whether the controller is in rain-delay mode or receiving a shutdown signal from a rain or freeze sensor.
A damaged or improperly configured sensor can prevent an otherwise functional system from running.
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Sprinkler heads and nozzles are exposed to mowers, vehicles, soil movement, roots, and normal wear.
Common problems include:
Cracked heads
Broken risers
Clogged nozzles
Missing nozzles
Sunken heads
Tilted heads
Heads blocked by grass or shrubs
Incorrect spray patterns
Improperly adjusted rotors
A head may appear functional while still distributing water poorly.
For example, a partially clogged nozzle may spray several feet short of its intended area. A tilted head may apply most of its water to one side. A head buried below the turf canopy may never distribute water correctly, even when pressure is adequate.
Turn off the irrigation water supply before removing or replacing components. Clean clogged nozzles carefully and replace damaged parts with compatible components.
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A functioning sprinkler head does not necessarily mean the area is receiving enough water.
Proper irrigation generally requires overlapping coverage. Water from one head should reach the neighboring head. This is often called head-to-head coverage.
Coverage problems can be caused by:
Heads spaced too far apart
Incorrect nozzles
Mixed head types within the same zone
Poorly adjusted spray patterns
Low pressure
Plant growth blocking the spray
Changes to patios, beds, fences, or landscaping
Sunken or tilted heads
Avoid mixing traditional spray nozzles, rotary nozzles, and large turf rotors within the same zone unless the precipitation rates have been carefully matched.
These components can apply water at dramatically different rates. One area may become saturated while another remains dry.
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A catch-can test helps determine whether a zone is applying water evenly.
Place several identical, straight-sided containers throughout the zone. Tuna cans, rain gauges, or irrigation catch cups work well.
Run the zone for approximately 15 minutes, then measure the water collected in each container.
The exact amount is less important during the first test than the consistency between containers.
If one container collects significantly more water than another, the zone likely has a distribution problem. Inspect the nearby heads for poor adjustment, clogged nozzles, incorrect patterns, low pressure, or spacing problems.
A catch-can test can also help estimate how long a zone must run to apply a specific amount of water.
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Pressure problems can affect one zone or the entire system.
Low Pressure on One Zone
If only one zone has low pressure, possible causes include:
A broken underground lateral pipe
A damaged sprinkler head
A valve that is not opening completely
A clogged valve or filter
Too many heads on the zone
A significant leak
Walk the entire zone while it is running. Look for bubbling water, unusually wet soil, or one head flowing much more heavily than the others.
Low Pressure Throughout the System
If every zone has low pressure, the issue may involve:
The main irrigation supply
A partially closed shutoff valve
A backflow device
A pressure regulator
A mainline leak
Changes in municipal water pressure
Problems involving the mainline, backflow device, or water supply should usually be evaluated by a qualified irrigation professional.
Excessive Pressure
High pressure often produces mist rather than larger water droplets.
Mist is easily carried away by wind and can create poor coverage even though the system appears powerful. Excessive pressure can also damage nozzles, seals, fittings, and sprinkler heads.
Pressure-regulated heads or properly sized pressure-regulating components may be needed.
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A constantly wet area does not always mean there is an underground pipe break.
Possible causes include:
A cracked pipe or fitting
A leaking sprinkler head
A valve that is not closing completely
Low-head drainage after the zone shuts off
Excessive run time
Poor soil drainage
Water flowing downhill from another area
Overlapping coverage
Pay attention to when the water appears.
If the area becomes wet only while the system is running, a damaged pipe, fitting, or head may be responsible.
If a low sprinkler head continues draining for several minutes after the system shuts off, gravity may be emptying the lateral pipe. A check valve or check-valve sprinkler head may help.
If an entire zone continues running after the controller shuts it off, the irrigation valve may be stuck open or damaged. Turn off the irrigation water supply until the valve can be repaired.
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A water meter can sometimes help identify a significant leak.
Turn off faucets, appliances, irrigation, and other water-using fixtures. Then observe the leak indicator on the water meter.
If the meter continues moving, water may be flowing somewhere on the property.
This test confirms water movement, but it does not prove that the irrigation system is responsible. Plumbing leaks, pool equipment, water features, and other fixtures can also cause meter activity.
Locating a hidden underground leak may require specialized equipment and a professional leak-detection company.
When a Zone Will Not Turn On
First, try operating the zone manually from the controller.
If every other zone works, the problem may involve:
The individual station output
Field wiring
A wire connection
The valve solenoid
The irrigation valve
Debris inside the valve
If no zones operate, check:
Controller power
Controller fuse or error messages
Water supply
Rain-delay settings
Sensor status
The common wire
The system’s master valve or pump, if equipped
Irrigation controllers contain both low-voltage wiring and, in many cases, line-voltage electrical connections. Homeowners should not open or repair energized electrical components unless they are qualified to do so.
When to Call a Professional
Basic inspection, nozzle cleaning, controller review, and catch-can testing are reasonable DIY projects for many homeowners.
Professional help is usually appropriate when the problem involves:
Mainline leaks
Backflow devices
Electrical failures
Buried wire faults
Valve replacement
Locating buried valves
Repeated pressure loss
Major underground leaks
Pump systems
System redesign
Significant excavation
Avoid random digging when a valve or wire cannot be located. Professional wire-tracing and valve-locating equipment can prevent unnecessary damage to the lawn and landscape.