We get a lot of phone calls in March and April—from Columbia, Bethesda, Bowie, Ashburn, you name it. Homeowners who were excited to get their lawns going again hit that controller for the first time in months and…
“Why won’t Zone 3 turn on?” “Why is water spraying out from under the deck?” “Why is the backflow leaking?”
Every year, it’s the same pattern. Different addresses. Same root cause.
The #1 reason irrigation systems fail in spring? They weren’t properly winterized.
Let’s walk through why that is, what fails first, what the warning signs are, and how to avoid becoming the next urgent spring service call.
This is They Ask, Bob Carr Answers—and today we’re talking about prevention.
What Really Happens When You Skip Winterization
Sprinkler systems are built to handle water pressure—not frozen water.
In the DMV, we see winter temps drop below freezing dozens of times each year. Even if the days are mild, nighttime lows below 32°F are enough to freeze water left in the lines, valves, or heads.
And when water freezes? It expands. That expansion can: – Crack lateral pipes underground – Shatter rotors and pop-ups from the inside – Split brass fittings and valve boxes – Destroy backflow preventers
Real Story: Ellicott City Freeze-Out
A homeowner called us in early March. Their system wouldn’t turn on, and water was spraying behind the shrubs. We found 6 cracked heads and a burst valve—all due to frozen water.
Total cost to repair: $1,850.
Cost of winterization the fall before? $175.
FAQ: Doesn’t the ground keep pipes warm?
Not if they’re too shallow. In our region, frost depth can reach 6–10 inches in a bad winter. Most lateral lines are only buried 6–12 inches. That’s why a single hard freeze can do serious damage.
Why Backflow Preventers Fail First
Backflows are usually mounted above ground, which makes them the most exposed part of your irrigation system. Even if you turn off your controller or shut off the water, any water left in the backflow can freeze, expand, and cause damage.
Common signs of backflow damage in spring: – Leaking at the union or test ports – Cracks along the brass body – Whistling or hissing when water flows – Full pressure loss when zones run
Real Story: Silver Spring Soggy Basement
A homeowner skipped winterization, figuring they’d “take care of it next weekend.” That weekend came with a deep freeze. The backflow cracked overnight, and when water resumed, it sprayed into the siding for hours. Repairs ran over $3,200.
FAQ: Can I just wrap the backflow in a towel or insulation?
Only if it’s drained first. Wrapping it without draining may insulate the water in, not out.
Smart Tip: We include backflow covers for all winterization clients—and we drain the unit before we insulate it.
How Frozen Valves & Wires Wreak Havoc
Valve boxes are supposed to stay dry—but after a rainy fall or heavy snow, they often collect water.
If you don’t winterize: – Water in the valve box can freeze and crack the plastic housing – Moisture corrodes solenoids and wire connectors – Frozen valves can get stuck closed—so your zone won’t run – Controllers send power over and over—until wiring fails
Case Study: Fairfax Frozen Box
We opened a valve box in April and found standing water and a cracked solenoid. The zone wouldn’t open, and the controller kept sending power—frying the wiring. Repair cost: $780.
FAQ: Is valve damage common after winter?
Only in systems that weren’t properly drained or sealed. If you’re seeing poor water flow or zones that won’t run, valve trouble is likely.
AI-Backed Patterns: Where It Fails Most
At TLC, we use AI to track trends in freeze-related damage. Here’s what we’ve learned from analyzing over 6,000 service calls:
- Older neighborhoods like Takoma Park, Bowie, and Alexandria with shallow installs see more lateral line cracks
- Clay-heavy soil zones like Ellicott City and Urbana hold cold longer, freezing faster
- Backflows facing north fail 2.3x more often than those facing south
- Properties with slope see more cracked heads (due to freeze-thaw expansion)
TLC Pro Tip: We flag high-risk systems and move them to the front of our fall winterization schedule—especially those with exposed pipework or elevated components.
FAQ: What if my neighbor skipped winterization and didn’t have problems?
They got lucky. We’ve seen systems go untouched for years, then suddenly break when one cold front hits just right.
Early Warning Signs in Spring
Even before your system runs, there are clues something went wrong: – Mushy or flooded spots in the lawn = underground leak – Backflow hissing = internal crack – Zone doesn’t activate = stuck or damaged valve – Head sputters = cracked riser or stuck rotor
Homeowner Story: Gaithersburg Geyser
The moment the system started, water shot 4 feet in the air from a cracked riser. The homeowner hadn’t realized winter’s effects until it was too late.
AI Benefit: TLC’s spring activation checklist includes zone pressure comparisons from previous years. If one zone shows 20% drop—we know where to look.
What Proper Winterization Looks Like
Here’s how we prevent spring failures with our winterization service:
- Shut off irrigation supply line
- Drain and isolate the backflow preventer
- Connect a 185 CFM commercial air compressor
- Blow out each zone until dry (multiple passes if needed)
- Open valves and verify controller shutdown
- Document with photos and notes in your TLC system file
Smart Scheduling: We use ZIP code-level weather modeling to plan your visit before the average frost hits.
Digital Proof: Every winterization visit includes: – Technician ID – Photos of each step – PDF report emailed to you and stored in your TLC dashboard
FAQ: Do I need winterization every year?
Yes. Even mild winters can bring surprise cold snaps. You don’t want to gamble a $7,000 system on a weather guess.
What to Do If Your System Already Failed
First—don’t panic. We see dozens of cases every spring and help homeowners recover fast.
Our steps: 1. Inspect controller, backflow, valve boxes, and all zones 2. Pressure test each zone individually 3. Use acoustic leak detection if needed 4. Prioritize urgent repairs, then schedule deeper fixes
TLC Warranty Tip: If you’re a TLC maintenance client and we winterized your system, we prioritize you for early spring service—and discount any related repairs.
Final Word from Bob
Spring is when your lawn should come back to life—not your irrigation problems.
The best way to avoid broken heads, stuck valves, and surprise repairs is to winterize the right way every fall. It’s cheaper, easier, and smarter.
And if you’re already dealing with spring failures this year, call us. We’ll diagnose, document, and rebuild what needs fixing—and get you on the path to a smarter system with AI monitoring, proactive service, and peace of mind.
Whether you’re in Bethesda, Ashburn, Laurel, or Leesburg—we’ve got your back.
They asked. Bob Carr answered.