Backflow Testing & Prevention
Test the device that stops sprinkler water from flowing back into the drinking supply.
Homeowner guide
Sprinkler Winterization in Lafayette, CO: A Short Guide
An irrigation system holds water in buried lines, valves and a backflow device. When that water freezes, something splits. A fall blowout and a few shutoff steps prevent the cost of a spring repair.
By the Lafayette Plumbers team ·
Why timing matters
Colorado can get a hard freeze in October, and sometimes before. Waiting until the first cold forecast leaves little time. Most owners plan the blowout for early to mid fall.
Boulder County's frost depth is 30 inches, so lines buried deeper survive. Many sprinkler lines are shallower than that, and the above-ground backflow device is exposed.
The blowout, step by step
Shut off the water to the system at the main irrigation valve. Connect an air compressor to the blowout port and work through each zone, one at a time, until only mist comes from the heads. Do not exceed the pressure rating of the pipe.
Never stay on one zone too long, because dry air can overheat sprinkler parts. Many owners hire a pro, since compressors and pressure settings are easy to misjudge.
Protecting the backflow device
After the blowout, close the shutoff valves to the device and open the test cocks so the body drains. Leave the handles at about 45 degrees so water cannot sit trapped between the valves.
If the device sits above ground, wrap it in an insulated cover made for the purpose. See backflow testing for why these devices need an annual test.
Fall checklist
Do these before the first hard freeze.
| Item | Action | Why |
|---|---|---|
| Irrigation lines | Blow out each zone with air | Removes water that can freeze |
| Backflow device | Close valves, open test cocks, insulate | Protects the body from splitting |
| Controller | Set to off or rain mode | Avoids running a drained system |
| Hose bibs | Remove hoses and drain | Prevents splits in the wall |
Controller, valves and hose bibs
Set the controller to rain mode or off, and clip the rain sensor if it needs a cover. Drain manifold valves and any inline filter. Disconnect hoses from every outdoor spigot.
A leaking hose bib in spring can mean a split from fall. See faucet and sink repair for outdoor taps.
Spring start-up
Open valves slowly in spring to avoid water hammer, then run each zone and look for geysers, soggy patches and broken heads. A zone that does not reach full pressure may have a split pipe.
Have the backflow device tested in spring if the provider requires it. Ask your plumber to check it for leaks at the same time.
Lafayette water rules
The City of Lafayette says year-round water restrictions are in effect and that drought response is being monitored. Check the city's current schedule before you set watering days.
A leaky system wastes water that the city wants to save. Fixing a split line promptly saves money and meets the spirit of the rules.
Signs you waited too long
Cracked heads, split risers and valves that leak after spring start up all point to freeze damage. A zone that never reaches full pressure may have a break in the line.
Photograph what you find and note the zone. A repair crew can then locate and fix the failures in one visit.
Doing it yourself or hiring out
Blowout work needs a compressor of the right size, safety glasses and a careful setting. Mistakes can damage heads or hurt someone. Many owners prefer to hire a professional who does this every fall.
If you hire help, ask how they set the pressure, how they handle the backflow device and whether they check each zone.
Protecting hose bibs and exposed pipes
Disconnect hoses and drain outdoor faucets before freezing weather. A frost-free bib helps but only if the hose is removed, because a connected hose traps water in the barrel.
Insulate exposed pipes in crawlspaces and garages. Foam sleeves are cheap and quick to fit.
Timing around Front Range weather
Cold snaps sometimes show up earlier than the calendar says. Watch the forecast and treat a night near freezing as a reminder to finish the work.
If a warm spell follows, you can still leave the system drained. Leave the water off until spring.
What to skip
Do not rely on gravity drains alone, since low points hold water. Do not run air at full compressor pressure, and avoid standing over a pressurized line.
If you are unsure, hire a professional. A short service visit costs far less than a broken main.
Why timing matters along the Front Range
Frost can arrive in October, and warm days may follow, which tempts owners to wait. A single hard freeze with water in the lines can split fittings and heads. Pick a date before the first forecast freeze rather than after.
Many people schedule the blowout the same week each year so it does not slip. A reminder on the calendar works as well as any tool.
Rain sensors and controllers
Switch the controller to rain mode or off once the system is drained, but keep power on if the clock holds your program. Clear leaves and debris from the sensor, and replace the backup battery.
If you use a smart controller, check that it has its latest settings before spring. A wrong schedule wastes water faster than a small leak.
Valve boxes and pipe insulation
Valve boxes can fill with water and freeze the valves inside. Check that lids fit, that the box drains and that no standing water sits in the bottom.
Insulate any exposed pipe above ground near the backflow assembly, and cover it with a breathable enclosure rather than plastic, which traps moisture.
Costs of skipping winterization
A freeze can split a pipe underground, and the damage often does not appear until spring. Digging up a buried line is a bigger job than a fall service.
Ask the contractor for a written price for the blowout. Prices differ by number of zones, so count yours before you call.
Common questions
Answers on sprinkler
Before the first hard freeze, usually early to mid fall.
Some owners do, but a compressor mistake can damage parts. A pro is safer.
Yes. Drain it and insulate it if it sits above ground.
You will see it in spring as a geyser or a soggy spot. Call for repair.
Related services
Faucet & Sink Repair
End drips, weak flow, stuck shutoffs and dripping outdoor spigots.
Water Line Repair & Replacement
Mend or replace the buried supply pipe that travels from the street meter to your house.
More plumbing guides
Preventing frozen pipes
Cold snaps split pipes in garages, crawl spaces and outside walls. Here is how to protect them before the next freeze.
Why the water bill jumped
A bill that suddenly climbs usually has a cause you can find. Check these likely suspects in order.
Finding the main water shutoff
When a pipe splits, the first move is the main valve. Find the valve, understand how it operates and know your options if it jams.
Speak with the phone desk
Need a backflow test or a spring repair?
Call the line, describe the system and ask about scheduling.
Call (720) 743-9476(720) 743-9476 · day and night