Why your sprinkler system leaves some areas dry and others soaked
An irrigation system is designed around a principle called head-to-head coverage: each sprinkler head is positioned so that its spray arc reaches all the way to the next head in every direction. When that overlap is maintained, water distributes evenly across the entire zone. When it breaks down — because a head is clogged, tilted, worn, or blocked by a shrub that didn't exist when the system was installed — you get gaps. Dry patches appear where arcs no longer meet. Saturated zones appear where multiple heads still overlap correctly. The lawn doesn't lie: brown and green areas map almost exactly to where the coverage has failed.
Water pressure plays an equally important role. Each type of head — spray heads, rotor heads, MP rotators — is calibrated to perform within a specific pressure range, typically 25–45 PSI depending on the head type. When pressure is too low, heads don't throw water far enough to achieve that designed overlap. When pressure is too high, spray turns to mist, wind carries it off target, and you lose significant water to evaporation before it ever hits the soil. Both conditions produce uneven coverage, but they look different: low pressure leaves obvious dry rings around each head, while high pressure produces a fine fog and soaks the area immediately around each head while leaving the middle of the zone dry.
Age and physical damage are the third major factor. Sprinkler heads get clipped by lawn mowers, slowly sink below grade as soil settles, accumulate mineral deposits in the nozzle orifice, and wear out their internal check valves over years of use. A system that covered the yard perfectly when it was installed five or ten years ago can develop significant dead zones gradually — often so gradually that homeowners attribute it to soil problems, turf disease, or drought stress rather than the irrigation system itself.
Uneven coverage isn't always the same problem — it depends on the pattern
The specific way your yard looks tells you a lot about which part of the system has failed — and matching your symptoms to the right cause is the fastest route to a fix.
What an uneven sprinkler system costs you if you leave it alone
The most immediate cost is the lawn itself. Persistent dry zones weaken turf root systems, making grass vulnerable to heat stress, weed invasion, and disease — particularly during summer months when the margin between adequate and insufficient water is narrow. Weeds like crabgrass and spurge are opportunistic; they establish fastest in thin, stressed turf exactly like the kind that develops in chronically under-watered zones. Meanwhile, the zones that are being overwatered develop their own problems: shallow roots (because water is always at the surface), fungal disease, and compaction from saturated soil. You end up with a lawn that has both drought stress and overwatering damage at the same time, which is genuinely difficult to diagnose without considering the irrigation system first.
According to the EPA's WaterSense program, the average household with an in-ground irrigation system uses about 9 billion gallons of water per year nationally — and roughly 50% of that is wasted due to inefficiency, including poor coverage, misting from excessive pressure, and overwatering caused by uneven distribution. Fixing coverage problems isn't just about a green lawn; in many municipalities, it translates directly to lower water bills and avoidance of seasonal water-use surcharges.
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What others have experienced
47 community experiences-
DM
Spent two summers blaming the heat and watering more, which just made the soggy spots worse and didn't touch the dry strip along the back fence. Turns out two heads near the fence had sunk about an inch below grade — the spray arc was hitting the ground before it could reach anything. Lifting and resetting them with riser extensions took maybe an hour and the back yard has been even ever since. Wish I'd looked at the heads first instead of just cranking up the timer.
31 found this helpful -
RS
Our zone 2 coverage got progressively worse over about three seasons. I finally ran it at night with a flashlight and noticed two of the rotor heads were barely rotating — they'd spin maybe 90 degrees and stall. Replaced both heads with the same brand/model and immediately got the full 180-degree arcs back. The brand I used before was fine; it was just wear. The maddening part is that the heads looked completely normal from the outside.
24 found this helpful -
TK
I thought I had a pressure problem because the whole system seemed weak, but a plumber friend pointed out that someone had partially closed the main shutoff valve at the backflow preventer — only about halfway open. I have no idea how long it had been that way, maybe since we moved in. Opened it fully and pressure went from basically useless to totally normal. I'm including this because I never would have thought to check it, and it was a free fix.
38 found this helpful
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