May is the critical pivot point between spring prep and summer demand—your sprinkler system must be fully functional before temperatures climb and lawns dry out. A single missed leak or misaligned head can waste thousands of gallons by July, and undetected valve issues often escalate into emergency repairs mid-season.
Priority Tasks
| Task | Time Required | Difficulty | Tools Needed |
|---|---|---|---|
| Inspect all sprinkler heads for damage or clogging | 45–90 min | Easy | Screwdriver, stiff brush, rag |
| Test zone-by-zone operation & timing accuracy | 60–120 min | Moderate | Timer manual, stopwatch, notebook |
| Clean or replace clogged nozzles and filters | 30–60 min | Easy | Needle-nose pliers, vinegar soak container |
| Adjust spray patterns to avoid pavement and overspray | 40–75 min | Easy | Hex key set, measuring tape |
| Check backflow preventer for leaks & proper function | 20–40 min | Moderate | Wrench, flashlight, pressure gauge (optional) |
Detailed Task Breakdown
Inspect all sprinkler heads for damage or clogging
Walk each zone slowly—look for cracked housings, sunken or tilted heads, and mineral buildup around nozzles. Use a stiff nylon brush dipped in white vinegar to scrub nozzle screens; rinse thoroughly. Replace any head with stripped adjustment screws or broken pop-up mechanisms—don’t force them. According to the U.S. EPA, 30% of residential irrigation water is wasted due to misaligned or damaged heads (WaterSense Program, 2022).
Test zone-by-zone operation & timing accuracy
Manually cycle each zone using your controller’s test mode. Time how long each runs versus programmed duration—±5% variance is acceptable. Note zones that don’t activate, shut off early, or run continuously. If more than one zone fails, suspect a wiring fault or controller battery issue (most controllers use a CR2032 battery that lasts ~2 years). Reset the clock and reprogram seasonal adjustments—many homeowners forget to shift from spring’s shorter cycles to May’s increased demand.
Common Seasonal Problems
- “Ghost watering”: Zones activating overnight—often caused by moisture in timer housing or failing solenoid valves
- Low-pressure zones: Usually indicate root intrusion in older poly lines or debris in valve diaphragms
- Uneven brown patches despite full coverage: Caused by compacted soil under heads—not equipment failure
- Backflow preventer dripping after shutdown: Suggests worn check valve seals (replace kits cost $12–$28, not full unit)
Tools & Supplies
Keep these on hand before you begin:
- Vinegar (for soaking nozzles and cleaning calcium deposits)
- Replacement nozzles (match your brand: Hunter MP Rotators, Rain Bird 1800 series, etc.)
- Backflow preventer rebuild kit (model-specific—check manufacturer label)
- Digital multimeter (to test solenoid resistance—should read 20–60 ohms)
- Zone map printed and laminated (handy if you’ve added beds or changed landscaping)
What to Do If…
Your controller displays "ERR" or blank screen
First, check the power source: GFCI outlets trip easily in damp spring conditions. Reset it. Then remove and replace the backup battery—even if the display works, a weak battery corrupts programming during outages. If still unresponsive, inspect wiring connections at the controller’s terminal block for corrosion.
A zone runs but water barely sprays
This isn’t always a clog. Turn off the main line and open the valve box. Look for discolored or swollen rubber diaphragms inside the valve—common after winter freeze-thaw cycles. Diaphragm kits cost $4–$9 and take under 10 minutes to swap. Don’t skip this: a failing diaphragm reduces flow by up to 70%, per Valve Repair Guide.
You hear hissing near a head or valve box
Hissing = air or water escaping under pressure—usually a cracked lateral line or loose fitting. Dig carefully around the sound source. If you find a split in black poly pipe, cut out the damaged section and install a compression coupling (not duct tape or epoxy). For PVC, use a primer/glue joint—but only if temps stay above 45°F for 24 hours post-install.
One zone has significantly lower pressure than others
Isolate the issue: turn off all other zones and run just the low-pressure one. If pressure improves, you likely have a partially closed isolation valve or a shared main line undersized for total demand. Check shutoff valves near the manifold—they’re often accidentally bumped during landscaping. If pressure stays low, inspect the zone’s valve for grit in the inlet screen—a frequent culprit after spring runoff.
Water pools around a head but doesn’t spray
This points to a broken riser or cracked body seal—not a clog. Pop the head and inspect the threaded base. If water gushes upward from the socket, the internal O-ring is compromised. Replace the entire head (O-rings aren’t field-serviceable on most models). For deeper insight, see our sprinkler head replacement walkthrough.
You notice algae or slimy residue in the filter screen
That’s biofilm—not just dirt. It forms when stagnant water sits in filters over cool, humid April nights. Soak screens in diluted bleach (1 part bleach to 10 parts water) for 15 minutes, then rinse. Install a pre-filter on your pump intake if you draw from a pond or well—well water irrigation systems require extra filtration to prevent recurring biofilm.
"A properly adjusted sprinkler system uses 20–30% less water than one installed without zone-specific calibration—and saves the average homeowner $120/year on water bills." — Irrigation Association Residential Water Management Report, 2023
Don’t wait for June’s heatwave to discover your system’s weak spots. A focused 2-hour May check prevents weeks of patchy grass, surprise repair bills, and municipal water waste notices. Cross off each task, update your zone map, and enjoy consistent greenery all summer—without chasing leaks at 9 a.m. on a Saturday.