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It’s that time of year again. You turn on your sprinklers, expecting a powerful mist to cover your lawn, but instead, you get a weak dribble or a sputtering cough. Half your grass is turning yellow, and the heads won’t even pop up all the way. Before you panic and assume you have a broken pipe or need to replace all your sprinkler heads, ask yourself one question: When was the last time you cleaned your secondary water filter?
If you live in Utah, you likely irrigate with “Secondary Water”—untreated water that comes from canals, reservoirs, and rivers. It’s great for saving culinary water, but it comes with a catch: it is full of algae, sand, and snail shells.
The “Green Box” Mystery
If you walk around your yard (usually near the sidewalk or the side of the house), you’ll find a green rectangular box in the ground. Inside that box is your main shut-off valve and a critical component called a Y-Strainer.
This filter is the only thing standing between that dirty canal water and your delicate sprinkler nozzles. Over the season (and especially at startup), this screen gets completely choked with debris.
When the screen clogs, pressure drops. When pressure drops, sprinklers sputter.
The 10-Minute Fix (Save $100)
You don’t need a landscaper to fix this. You just need a pair of pliers and a bucket of water. Here is how to do it:
Step 1: Turn Off the Water Find the handle on the pipe leading into the filter (in the green box). Turn it perpendicular to the pipe to shut off the flow. If you skip this, you will get a mud bath in Step 2.
Step 2: Open the Cleanout Cap Look for the “Y” shaped part of the pipe. On the angled leg of the Y, there is a large nut or cap. Use your pliers (or a wrench) to slowly unscrew it.
- Warning: Even with the water off, there is still pressure in the system. Open it slowly to let the water hiss out.
Step 3: Pull the Screen Once the cap is off, reach inside and pull out the cylindrical mesh screen. Don’t be surprised if it looks like a tube of mud or is packed with tiny snail shells.
Step 4: Scrub It Clean Take the screen to a hose bib or swirl it in a bucket of water. Use an old toothbrush if the algae is stuck in the mesh. You want it to look shiny and metallic again.
- Pro Tip: Check the screen for tears. If the mesh is ripped, debris is getting into your sprinkler heads. You can buy a replacement screen at any local hardware store for a few dollars.
Step 5: Reassemble Slide the clean screen back into the housing. Screw the cap back on (hand tight, then a quarter turn with the wrench—don’t overtighten!). Turn the water handle back on slowly and check for leaks.
What If They Are Still Sputtering?
If you cleaned the filter perfectly but your pressure is still weak, or if you notice a patch of grass that is unusually soggy and green compared to the rest, you might have a bigger problem.
You could have a crack in the underground line between the filter and the valve box. This is common after Utah’s freeze-thaw winter cycles.
This is where a plumber (not a landscaper) is your best bet. We can locate underground leaks without digging up your entire yard.
Need Help Diagnosing Low Pressure?
If your filter is clean but the water just isn’t flowing, don’t let your lawn burn up.
Let’s Fix Plumbing specializes in diagnosing pressure issues and finding hidden leaks that ruin your landscaping budget.
- Suspect a leak? Learn more about our Leak Detection Services.
- Find us on Google Maps: Let’s Fix Plumbing
- Get a Professional Opinion: Contact Us Here