You run your sprinklers on schedule. You may even add extra minutes when the weather turns hot. Yet the same brown patches keep showing up in the same places. That frustrating pattern often points to underlapping sprinkler zones, a coverage problem where your irrigation system doesn’t reach every part of your lawn.
The good news is that underlapping zones can almost always be fixed, and often the fix is a simple adjustment, not a full system overhaul. At Santa Fe Sprinkler Repair, we see this problem all the time. In this guide, we’ll explain what underlapping is, why it happens, and how to spot it early.
Key takeaways:
Your irrigation system is divided into zones. Each zone is a group of sprinkler heads controlled by one valve, and each zone waters a specific section of your yard. When a zone is working well, the spray from each head overlaps with the spray from neighboring heads.
Irrigation pros call this head-to-head coverage. It means water from one sprinkler head reaches all the way to the next head. This overlap matters because sprinklers don’t spread water evenly across their full range. The area closest to the head usually gets more water, while the outer edge gets less.
Underlapping happens when the spray patterns don’t overlap enough, or don’t meet at all. The result is a strip, ring, or patch of lawn that gets little or no water. Over time, those areas dry out, thin, and turn brown while the rest of the lawn looks healthy.
Underlapping can look like other lawn problems, such as pests, disease, or poor soil. Here are the most common clues that the issue is coverage:
If you notice two or more of these signs, there’s a good chance your zones aren’t covering the full lawn.
Underlapping rarely has just one cause. In many yards, it’s a mix of small issues that add up. Here are the most common culprits we find.
Sprinkler heads need the right pressure to throw water the full distance they were designed for. When pressure drops, the spray falls short. That leaves a gap between heads. Pressure problems can come from leaks in underground pipes, a partially closed valve, too many heads on one zone, or issues with your water supply.
Heads get bumped by lawn mowers, foot traffic, and vehicles. Soil can also shift over time. A head that’s tilted even slightly can send water into the air, onto the sidewalk, or into one area while missing another. Heads that rotate in the wrong arc create the same problem.
Dirt, sand, and mineral buildup can block nozzles and shorten the spray. Worn nozzles may spray in an uneven pattern or produce a weak stream. Either way, the water doesn’t reach as far as it should.
Pop-up heads can sink below the soil line as grass grows and thatch builds up. Once that happens, the grass itself can block the spray. Overgrown shrubs, new garden beds, and lawn decorations can also get in the way.
Different nozzle types put out water at different rates. If one zone mixes rotors and spray heads, or uses nozzles with mismatched flow rates, some areas will get too much water while others get too little. This often happens after quick replacements with whatever part was on hand.
Some systems were never laid out with proper head spacing. In other cases, the original design worked well until the yard changed. A new patio, an extended lawn, or a mature tree can create coverage gaps the system was never built to handle.
A faulty valve or solenoid may keep a zone from opening fully. That reduces flow and pressure for every head in the zone. Controller issues can also cause a zone to run for too short a time or skip cycles altogether.
It’s tempting to live with a few brown patches. But underlapping zones cause bigger problems than a less-than-perfect lawn.
Grass in dry spots becomes stressed and thin. Weak turf is more open to weeds, insects, and disease. Once grass dies off, you may need to reseed or lay new sod. That costs far more than fixing the coverage problem.
The most common reaction to dry spots is to water longer. Unfortunately, this floods the areas that already get enough water just to give the dry areas a little more. You pay for that extra water, and the overwatered sections can develop shallow roots, fungus, and runoff.
A lawn with green and brown patches hurts your home’s curb appeal. Whether you plan to sell or simply want a yard you’re proud of, even coverage makes a big difference.
Sometimes underlapping is a symptom of a deeper issue, such as a leaking pipe or failing valve. Ignoring the dry spots can allow that problem to grow and lead to more expensive repairs later.
Before you call for help, you can do a quick test to see how evenly your system waters. Many homeowners call it the “catch cup” test.
While the zone runs, walk the area and watch each head. Look for heads that are tilted, sunken, blocked, misting, or not spraying at all. Take notes or photos. This information helps a technician diagnose the issue faster.
This test can confirm a problem, but it won’t always reveal the cause. That’s where a professional inspection comes in.
At Santa Fe Sprinkler Repair, we don’t just turn up the run time and hope for the best. We find out why your zones aren’t covering the full lawn, then fix the root cause. Here’s how our process works.
We start with a full coverage analysis to see how water is spread across your lawn. We check each zone, measure spray distances, and map out the gaps. This shows us exactly where your yard is missing water.
Next, we run pressure testing and flow rate testing. These tests tell us whether each zone has enough pressure and flow to push water to its full range. If pressure is low, we track down the reason, whether it’s a leak, a valve issue, or a zone with too many heads.
Many coverage problems come down to the heads themselves. Our sprinkler head repair service includes:
Once the parts are working correctly, we fine-tune each zone. We adjust spray arcs, set the right radius, and make sure every head reaches its neighbor. In some yards, we may recommend adding or relocating heads to fill gaps left by landscape changes.
If testing reveals a deeper issue, we handle that too. Our team provides pipe leak repair, valve repair, solenoid repair, and controller repair. We also offer leak detection using advanced tools to find problems hidden underground.
Finally, we review your controller settings. With soil moisture testing and a weather-based irrigation evaluation, we help set a schedule that gives your lawn what it needs without wasting water.
When dry spots appear, a few quick fixes can make things worse. Watch out for these:
If dry areas show up between sprinkler heads, along edges, or in the same pattern year after year, coverage is the likely cause. A catch cup test or professional coverage analysis can confirm it.
Yes. Most underlapping problems are fixed with head adjustments, nozzle changes, pressure repairs, or a few added heads. A full system replacement is rarely needed.
It depends on the cause. Simple head and nozzle adjustments can often be done in one visit. Leaks or valve problems may take a bit longer.
In many cases, yes. Once every area gets the right amount of water, you no longer need to overwater the whole yard to reach the dry spots.
Underlapping sprinkler zones leave dry spots, waste water, and weaken your lawn over time. The cause is usually a fixable issue, like low pressure, misaligned heads, clogged nozzles, or zones that need adjusting. With the right diagnosis, your system can water every inch of your yard evenly.
Let our team find the gaps and fix them for good. Request services today by calling Santa Fe Sprinkler Repair at 346-385-0008.
