Irrigation System Spring Startup & Zone Inspection

ContextNever open a main irrigation valve in a single motion. Turn the handle one quarter-turn, then pause for a full 60 seconds and listen for gradual water movement in the supply line. If you hear sharp banging or thumping (water hammer), slow down further. Open another quarter-turn, pause again, and continue until the valve is fully open — a process that should take at least two to three minutes in total. Rapid pressurization can fracture PVC fittings that have become brittle from years of UV exposure or from the micro-stress of winter freeze cycles, especially at elbow and tee connections buried just below grade.

ContextIf your backflow preventer has small quarter-turn test cocks, attach an inexpensive irrigation pressure gauge (available for $10 to $20 at any hardware store or irrigation supply) to read system supply pressure. Healthy residential irrigation systems operate between 40 and 65 PSI. Readings above 80 PSI cause spray heads to mist — which dramatically reduces application efficiency and accelerates nozzle wear. Readings below 30 PSI prevent rotors from completing their full arc. If pressure is too high, a pressure regulator on the supply line costs $25 to $75 and protects the entire system. Write down your reading — it becomes a useful baseline when diagnosing zone performance issues later in the season.

ContextWith the system pressurized but no zones commanded open, walk every area of the system and listen. A quiet hissing or trickling sound from below grade almost always means a cracked lateral pipe or a valve solenoid that is stuck open. Soft ground or a wet patch in an area that sprinkler heads do not reach confirms an underground supply-side leak. Mark these locations with a flag or colored paint before beginning zone testing — it is easy to lose track of exact positions once you start running zones. A lateral line repair by a contractor typically runs $100 to $300.

ContextRun each zone manually from the controller's 'manual run' or 'test' function. Do this during daylight in calm wind — wind distorts spray patterns enough to make coverage gaps invisible. Walk directly to that zone's coverage area as soon as you start it and watch every head come up. Any head that stays flush, dribbles instead of sprays, or tilts sideways warrants hands-on inspection before you close out that zone. Time the lag from zone activation to full head extension: a delay longer than 15 seconds may indicate a partially closed zone valve or a significant pressure drop in that zone's lateral.

ContextWhen retracted, spray and rotor heads should sit flush with or no more than one quarter inch above the surrounding turf. Heads sitting too high are the primary cause of mower-blade strikes — a leading cause of cracked stems and leaking body seals. Heads sitting too low, typically from soil settlement, may not pop up fully under normal operating pressure and deliver an uneven arc. If a head has sunk, dig around the riser and install a riser extension (sold in half-inch increments for under $5 each) rather than pulling up the entire lateral — it is a five-minute fix.

ContextRotor heads sweep back and forth through a programmed arc. A head that stalls mid-arc, reverses too early, or fails to return to its start position almost always has debris in the gear drive. Remove the head body, rinse the filter screen under clean running water, and reinstall. Some debris requires a quick soak in white vinegar to dissolve mineral deposits. Rotor arc and distance are adjustable: Hunter I-20 and Rain Bird 5000 series both use a flat-head screwdriver in the top slot to set arc from 45 to 360 degrees. Heads that spray driveways, sidewalks, or structures not only waste water but create slip hazards; adjust them now rather than after a neighbor complaint.

ContextThe irrigation industry standard for turf zones is head-to-head coverage: each head's spray arc should reach the adjacent head. Walk the zone while it is running and observe the spray boundaries. When this standard is met, you see overlapping arcs with a slightly wet overlap zone in the center. Visible dry triangles or diamond-shaped gaps will produce dead patches mid-summer, often blamed on heat or drought when the real cause was an inspection missed in spring. Gaps usually mean a head was removed and not replaced, a nozzle is partially clogged, or a head has rotated out of its original position.

ContextTwist nozzles counterclockwise to remove (most Hunter and Rain Bird nozzles come off easily by hand). Hold each nozzle up to a light source and look through the orifice — it should be a clean, precise opening. A clogged nozzle can often be cleared with a straightened paper clip or the pin tool on a Hunter adjustment key. Replace any nozzle with a cracked body or deformed rubber seal; they cost $0.50 to $2.00 each. More importantly: confirm all nozzles in a single zone are from the same matched-precipitation-rate series, typically color-coded by manufacturer. Mixing nozzle series — a common result of DIY repairs over the years — creates alternating wet and dry zones even when arcs look correct, because output volume per zone area differs.

ContextDrip zones require a different inspection method because nothing dramatic is visible from a distance — emitters deliver water at 0.5 to 2 gallons per hour directly at soil level. After activating a drip zone, walk the full length of the drip line and press your index finger to the soil about one inch from each emitter location — the soil should be noticeably damp within 90 seconds of zone activation. A blocked emitter that appears intact is almost always clogged with mineral scale throughout its body; replace the emitter body entirely rather than attempting to poke it open. A bag of standard drip emitters runs $8 to $15 for 10 to 20 pieces and takes a few minutes to swap across an entire bed zone.

ContextSpring soils are already saturated from snowmelt and early rainfall, and turfgrass root systems are at their shallowest depth until late spring growth. Running summer duration times in April overloads clay soils and causes anaerobic root conditions. A practical starting point: reduce all zone run times by 40 to 60 percent from your late-summer baseline. Turf in a temperate climate typically needs about 1 inch of water per week in spring versus 1.5 to 2 inches in peak summer. Drip zones for established shrubs often need no irrigation at all in a normal spring — withhold drip zone watering until the top two inches of bed soil dry out, which you can verify with a finger-press test.

ContextSmart controllers (Rachio 3, Hunter Hydrawise, Rain Bird ESP-Me with weather module) use a seasonal adjustment percentage to scale all zone run times automatically based on local evapotranspiration data. In spring, most manufacturers recommend starting at 50 to 60 percent of your peak summer baseline. If your controller connects to a public weather station for ET data, verify it is pulling from a station within five miles — a station from a different microclimate or elevation can produce significant over- or under-watering. Open the controller's companion app and confirm the assigned weather station has not been changed or removed since last season; this resets silently in some firmware updates.

ContextMunicipal watering restrictions change year to year and are often stricter in drought years. Before finalizing your schedule, check your local water utility's current-season restriction page — even if you verified it last year. Violations in many municipalities carry fines of $50 to $500 for repeat offenses. Also audit your start times: irrigation scheduled between 10 a.m. and 6 p.m. can lose over 30 percent of applied water to evaporation from spray heads on warm days. Controllers that allow multiple program start times are a common source of accidental schedule doubling — a zone appearing to run twice its intended duration is almost always a second start time set on the same program.

ContextThe rain delay button — which postpones all watering for 24, 48, or 72 hours — should be tested now, before the first rainstorm of the season. Activate a 24-hour delay and confirm the display shows an active delay and that the next scheduled cycle is suppressed. Then run a manual zone from the keypad. If you cannot manually activate a zone independently of the schedule, diagnosing any mid-season problem becomes far harder. Write the controller model number on a piece of tape inside the valve box or inside the controller door, and confirm that the manufacturer's PDF manual is bookmarked or saved to your phone — controller interfaces are rarely intuitive under time pressure.

ContextFind your home's main water meter (typically at the street or property line). Note the reading on the dial or digital display, then confirm all interior water use is paused. Manually activate your full irrigation system for a five-minute run, then shut it off. Wait 15 minutes without using any water anywhere in the house, then re-read the meter — the sweep hand or LCD should show no movement whatsoever. Any continued movement indicates water flowing somewhere in the system with no zone commanded open, a symptom of a valve that does not fully close (often called a 'weeping valve'). This condition runs continuously and invisibly until a water bill reveals it months later.

ContextEach valve box should be dry at the bottom after non-rainy weather. Standing water inside a box indicates a valve body is seeping internally or there is a crack in the nearby lateral. While the lid is open, press gently down on each solenoid — the cylindrical plastic cap on top of each valve body. It should feel firmly seated and not wobble. A loose, corroded, or easily-lifting solenoid may have a broken wire connection; solenoid bodies cost $10 to $25 and are among the most DIY-friendly repairs in irrigation. Also look for ant mounds or vole tunnels inside the box — rodents actively chew irrigation wiring, producing intermittent zone failures that are extremely difficult to trace without opening every box.

ContextMisting — a fine fog dispersing from around a spray head rather than a clean arc — is a sign that operating pressure at that head exceeds 80 PSI. Pressure-regulating stems (available for most Hunter and Rain Bird head bodies for $3 to $6 each) drop output to the optimal range and install without tools in under a minute. Puddling at a head's base — water pooling directly around the stem rather than being thrown outward — indicates either a head tilted below grade or a nozzle that is partially blocked, forcing flow back down the riser. Correct a tilted head by digging out the surrounding soil, adjusting the riser angle, and packing the excavation firmly before replacing the turf plug.

ContextUse the notes section of this checklist or a separate notepad to record the specific condition of each zone during startup: which zone, which head position (count from the valve), and what you found or fixed. 'Zone 3, Head 2 — nozzle replaced, arc corrected to 180°' takes ten seconds to write and eliminates guesswork if that head needs attention again in August or during next spring's startup. A written record is also useful if you hire a contractor mid-season and want to communicate efficiently about previously identified issues.

ContextBefore repairing cracked heads, broken risers, or leaking valve bodies, photograph the damage in place. Before-state photos establish the condition at startup and are useful if a contractor ever disputes whether they caused damage during a separate service visit. After-repair photos confirm what was done and give you a visual reference for next spring. Store these in a phone folder labeled by year and 'irrigation startup' — cloud-synced photos are searchable by date and geotagged to the exact location in your yard.

ContextIf any work was done on the system — by you, a landscaper, or a contractor — verify that your zone map reflects the current configuration. An accurate map does not need to be precise: a hand-drawn sketch on paper noting valve box locations, head count per zone, head types, and any drip zones is far better than nothing. A zone map created once takes about 20 minutes and pays off every time you need to describe a problem to a contractor, troubleshoot reduced coverage, or hand the system off to a new owner.