If you live on Oahu, your irrigation system works harder than almost anywhere on the mainland. There’s no winter shutdown, the water is hard and mineral-heavy, and salt air on the coasts chews through fittings. That combination means small problems rarely fix themselves — they quietly get worse. Here are the five signs worth acting on.
1. Dry patches that show up between mowings
If one corner of the lawn browns out while the rest stays green, a head or a whole zone probably isn’t delivering. Run that zone manually and watch: a head that dribbles, sprays sideways, or doesn’t pop up at all is the usual cause.
2. A head that mists instead of sprays
A fine mist drifting in the trade winds means the system pressure is too high or a nozzle is worn or scaled up with hard-water minerals. You’re paying to water your neighbor’s driveway. Worn nozzles are a cheap, often DIY fix.
3. A water bill that climbs for no reason
Because systems here run 12 months a year, a slow underground leak can add up for months before you notice. Look for a spot that’s always soft or wet, even days after the last run — that’s often a cracked lateral line or a valve that isn’t sealing.
4. A zone that won’t turn on (or won’t turn off)
This is usually electrical or a valve part: a failed solenoid, a torn diaphragm, or wiring corroded by moisture. If every zone is dead, suspect the controller or transformer — especially after a Kona-storm power surge.
5. Fittings that look corroded or crumble when touched
On leeward and beachside lots, salt air seizes brass valves and eats aluminum. If the visible hardware looks chalky or fragile, what’s underground is usually worse — and worth a professional look before a small repair becomes a dig-up.
DIY or call a pro?
Swapping a head, clearing a nozzle, or replacing a basic controller are fair game for a handy homeowner. Call a pro for valve and manifold work, multi-zone pressure loss, electrical faults, and anything touching the BWS backflow preventer — that’s a code item on Oahu, and getting it wrong can contaminate your drinking water.
FAQs
How often should I check my sprinkler system on Oahu?
Because Oahu systems run year-round, a quick walk-through every season (run each zone, watch for dry spots, misting heads, and pooling) catches most problems early. A professional tune-up once a year is plenty for most homes.
Is a higher water bill always a leak?
Not always, but on a year-round system it's the most common cause. Before assuming a rate change, run each zone and look for soft, always-wet spots — that's usually an underground lateral leak or a valve that won't fully close.