If your grass has some patches that stay green and others that go crispy no matter how long you water, the problem usually is not you forgetting to water. It is that your sprinklers are not putting water down evenly, and you have no idea how much any zone actually delivers. A catch, can test answers both questions in about an hour, with stuff you already have in the kitchen.
The idea is simple. You set out a bunch of identical containers across a zone, run the sprinklers for a set time, then measure how deep the water is in each can. That tells you the real output in inches per hour and shows you exactly where the dry and soggy spots are. Texas A&M’s Water University treats this catch, can audit as the starting point for any smart watering plan, and it costs almost nothing to do.
What do I need to run a catch, can test?
You need six to eight identical straight-sided containers per zone, a ruler, and a timer. Empty tuna cans are the classic choice because they are short, flat-bottomed, and all the same size. Cat food cans, plastic cups, or small Tupperware work just as well, as long as every can in the test is identical. Straight sides matter, because a bowl that flares out will read water depth wrong.
Grab a notepad or your phone to write down numbers, and a ruler that shows sixteenths of an inch. That is it. No special gear, no meter to buy. The whole point of this test is that any homeowner can do it on a Saturday morning.
How do I set up and run the test?
Place the cans across one zone in a rough grid, then run that zone for exactly 15 minutes. Spread the containers out so some sit near the heads, some sit in the middle, and some sit in the corners and the dry spots you already worry about. Do not bunch them together. You want a spread that represents the whole zone, not just the easy middle.
Do one zone at a time. Turn on the zone, set your timer for 15 minutes, and let it run its normal pattern. When the time is up, shut it off and go measure before the water soaks away or evaporates, which happens fast in Central Texas summer air. Then gather the cans, dump them, and move to the next zone. Label your notes by zone so you do not mix them up, especially if you have front and back systems or a mix of spray heads and rotors.
How do I read the results?
Measure the water depth in each can in inches, then do a little easy math. Since you ran for 15 minutes, which is a quarter of an hour, multiply each depth by four to get inches per hour. So a can holding half an inch means that spot is getting two inches per hour. Write down every can’s number.
Now look at two things. First, the average, which tells you the zone’s output rate. Second, and more important, the spread between your highest and lowest cans. This spread is your uniformity, and it is where most lawns fail. The Irrigation Association points out that even professionally installed systems commonly waste water because of poor uniformity, not because of the total volume. If your driest can holds less than half what your wettest can holds, water is landing unevenly and no run time will fix that until the heads get corrected.
What do the dry and soggy spots tell me?
Uneven cans point straight at a hardware problem you can usually see and fix. A can that is nearly empty next to full ones means a head is clogged, sunk below the grass line, tilted, or blocked by a shrub. A can that overflows while its neighbors sit low often means a head is stuck, mismatched, or throwing short. In our clay soils around the I-35 corridor, heads settle and tilt as the ground swells and shrinks through wet and dry spells, so tilt is a common culprit here.
Walk the zone while it runs and watch the pattern. You are looking for heads that mist instead of throwing droplets, heads that spray the sidewalk or fence, and heads that barely pop up. Some of these are five-minute fixes with a screwdriver, like straightening a head or clearing a nozzle. Others, like mixing rotors and spray heads on the same zone or a cracked line underground, are worth a call for sprinkler repair before you waste another month of water on a system that cannot win. If you want the whole setup checked and dialed in, our irrigation team runs this exact audit as part of a tune-up.
How do I set real run times from my numbers?
Once you know a zone’s inches-per-hour rate, you can water to a target instead of guessing. Most Central Texas lawns want about one inch of water per week in the heat, split across two or three days so it soaks in instead of running off our tight clay. If your test says a zone puts down two inches per hour, then a half inch of water takes 15 minutes, so two runs of about 12 to 13 minutes gets you close to an inch for the week.
Split long run times into shorter cycles with soak time between them. Our clay and caliche soils cannot absorb water as fast as a spray head throws it, so a straight 20-minute run mostly runs down the curb. Two or three short cycles with a rest in between let the water sink where the roots are. This cycle, and soak trick, paired with mowing at the right height, does more for a struggling lawn than any amount of extra watering. If mowing height and lawn health are part of your problem too, our lawn mowing crews set turf up to hold moisture better through the summer.
How often should I redo this, and what changes over time?
Run the test once every spring, before the real heat hits, and any time new dry patches show up. Sprinkler heads do not stay put. They sink into soft ground, get bumped by mowers, clog with grit, and drift out of alignment over a season. The numbers you get in March will not match August, so a yearly baseline keeps you honest and catches slow problems before they scorch a section of lawn.
Homeowners around Austin deal with this more than most, because our swings from flash storms to long dry stretches push heads around and stress the whole system. Spending one hour a year on a catch, can test saves water, saves money on the bill during watering restrictions, and keeps you from replacing sod that only died because one head quit.
Want it handled right the first time? Corral Bros can audit your system, fix the uneven heads, and set run times that match your soil and your zones. Get a free quote or call us at (737) 404-9343.