A woman called me in tears. Her brand new $4,000 irrigation system was flooding her basement window wells. The installers had set the heads too close to the foundation.
Three rotors aimed directly at house walls and a blanket 60-minute schedule create runoff and uneven coverage. Inspect heads placed near the foundation before adjusting run times.
Move heads outward where layout permits, adjust arcs away from the house, and base run times on measured precipitation rate; many spray zones need shorter cycles, such as 25 minutes, rather than a universal 60-minute setting.
That adjustment cost $200 and took two hours. The original installers had walked away from a system. That system would have caused thousands in foundation moisture damage.
Those categories are coverage problems, pressure problems, mechanical failures, controller errors, and winter damage. Each category has a distinct set of symptoms and a clear fix path.
Why are there dry spots in my lawn even though the sprinklers are running?
Dry spots that persist when sprinklers run consistently point to one of three causes. One cause is a sprinkler head that has sunk below grade. It sprays directly into the grass canopy without clearing it.
Another cause is an arc setting that misses the dry area entirely. The third cause is a clogged nozzle. A clogged nozzle reduces throw distance. The reduction is 30 to 50 percent from the manufacturer’s rated specification.
Look for sunken heads by walking the dry zone during operation with the system running. Watch for heads that spray below the top of the surrounding grass. A pop-up riser should extend at least 2 inches above the soil surface when pressurized.
If the grass blades are taller than the water stream, the spray never reaches the canopy. The grass directly around the head gets all the water. Everything beyond stays dry.
Clear a sunken head by digging around its body, adding a 2- or 4-inch PVC riser extension between the head and supply line as needed, then backfilling with compacted soil.
If the head height is correct, check the nozzle for debris. Remove the nozzle cap with a flathead screwdriver and inspect its small openings with a flashlight.
Sand, mineral deposits, and grass clippings lodge in nozzle openings. They distort the spray pattern into a narrow jet. Clean the nozzle with a small wire brush or a compressed air blast from a handheld duster.
If cleaning does not restore throw distance, the nozzle has internal wear from abrasive well water. Replace the entire nozzle for $3 to $6 per head. support/sprinkler-head-adjustment-guide-how-to-set-spray-pattern-distance-and-arc/). There The related guide covers matching nozzles to site conditions.
What causes low water pressure in my sprinkler system?
Low pressure produces misting rather than solid water streams. Or it leaves heads barely popping up above the grass canopy. This problem typically stems from a partially closed main shutoff valve.
It could also stem from a clogged valve filter screen. Or it could be a pipe leak that diverts flow volume away from the sprinkler heads.
Start by checking the main shutoff valve at the house or meter. A half-open valve reduces pressure throughout the system regardless of pump or municipal-supply rating.
Open the valve fully counterclockwise until it stops. If pressure remains low, locate the valve manifold and inspect each valve’s internal filter screen.
This dome-shaped stainless-steel screen catches sediment before it reaches the valve diaphragm chamber. Unscrew the valve bonnet and lift the diaphragm assembly to reach it.
Rinse the filter screen under running water. Sediment-clogged screens restrict flow to individual zones while leaving other zones unaffected.
A whistling or gurgling sound at a specific location indicates a pipe leak. That leak drains water before it reaches the heads.
Locate pipe leaks by walking the system while it runs and looking for unusually wet soil patches or grass strips that are greener than the surrounding area.
Look for small depressions where water has washed away soil around the leak. Dig at the leak site and cut out the damaged pipe section.
Install a slip coupling with PVC primer and solvent cement. Test pressure at the nearest hose spigot while a zone runs; a drop of more than 15 PSI can indicate an undersized supply line or meter. support/sprinkler-systems-complete-guide/). There The related guide explains pipe sizing and its effect on pressure.
Why are my sprinkler heads not popping up all the way?
Sprinkler heads struggle to pop up fully. Or they rise only partially above the grass canopy. This issue has one of three causes.
The first is a blocked wiper seal that binds the stem against the barrel. The second is insufficient operating pressure below the head’s rated minimum of 15 to 25 PSI for spray heads. The third is a broken spring that cannot lift the internal riser column.
Test each head manually. Pull the stem upward with gentle hand pressure. If the stem rises smoothly and holds position, the spring and seal are functional.
In that case the problem is system pressure. If the stem resists upward movement or feels gritty, the wiper seal around the stem has accumulated mineral deposits and dirt. This binds the stem to the barrel.
Retract the stem fully, apply an irrigation-safe spray lubricant around the wiper-seal gap, and cycle the head several times by pushing the stem down and pulling it up.
This distributes the lubricant. If the wiper seal still binds, remove the entire head and disassemble the internal riser assembly.
Clean the barrel and wiper seal with a soft brush and warm water. Inspect the spring inside the head; a rusted or weakened spring prevents pop-up even with adequate pressure.
A replacement spring costs $2 to $4. It slides into the head body without removing the head from the riser. If Replace the spring and the head still fails to pop up, the wiper seal has hardened from UV exposure.
Replace the failed spring assembly or the entire head, typically for $8 to $15, then check operating pressure at that location with a gauge on the nearest hose spigot.
If the reading remains below 25 PSI, the supply problem traces back to the valve or main line. support/how-to-fix-a-leaking-sprinkler-valve-step-by-step-repair-guide/). There The related guide covers diaphragm and solenoid issues that affect downstream head performance.
How do I fix sprinkler heads that leak water after the system shuts off?
Heads continue dripping or weeping water for several minutes after the zone valve closes. This indicates low head drainage. Water left in the lateral pipe after the valve shuts drips out through the lowest head on each zone.
Gravity pulls the standing water down to the lowest point in the pipe run. That point is usually a sprinkler head.
Low head drainage is a design condition rather than a component failure. But it causes soggy spots around the lowest heads. It can attract pests and promote fungal growth.
- Fix low-head drainage by installing check valves in the lowest heads on each zone. Check-valve heads contain a spring-loaded seal that blocks water from exiting when system pressure drops below 5 to 10 PSI. A head with a factory-installed check valve costs $10 to $15. A standard head costs $6 to $10.
- Replace the lowest two or three heads on each zone with check-valve models. If low-head drainage persists, the lateral pipe likely has a dip or sag that traps more standing water than the check-valve spring can hold back; verify the grade at the low point before opening the lateral line.
- Install a small drain valve that opens automatically when pressure drops. This allows trapped water to exit into a gravel sump rather than through the heads.
- Install a 6-inch-deep gravel sump at the drain valve location. This prevents soil erosion from the discharged water. The related guide covers low-drainage scenarios in the related drip irrigation types guide. There The related guide explains how emitter placement affects drainage patterns.
References
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edu/troubleshooting-home-irrigation-systems)