Backflow Testing & Prevention
Yearly testing and upkeep of the assembly that protects drinking water from sprinkler backflow.
Homeowner tips
Winterize Sprinklers and Outdoor Faucets in Westminster, CO
Before the first hard freeze, disconnect hoses, shut off the interior valve to outdoor spigots and drain the sprinkler system and its backflow assembly.
By the Westminster Plumbing Co. team ·
Hoses and hose bibs
Disconnect every hose, including short ones on a splitter. A connected hose traps water in the spigot, and a freeze can split the pipe behind the wall without any sign until spring.
If your spigots are standard, close the interior shutoff, open the outdoor spigot and let it drain. A frost-free model still needs the hose off, since water trapped in the barrel can freeze.
Draining the sprinkler system
Close the supply, open the drain valves and, if the system has a blowout port, use compressed air to push water out of the lines. Blowouts need the right pressure and a careful hand, because too much air damages heads and pipe.
Many owners hire a contractor for the blowout each fall. Ask what pressure they use and whether they cover every zone.
Backflow assemblies
The backflow preventer on an irrigation line is usually above ground and holds water. A freeze can crack the body. Close the supply valve, open the test cocks and drain the assembly. Some owners remove and store it indoors.
Westminster requires approved assemblies tested at installation and annually afterward by a certified tester, with results reported to the city's cross-connection control team. Plan the test for spring.
Fall winterizing checklist
Work from the outside in.
| Item | What to do | Why |
|---|---|---|
| Hoses | Disconnect and store | Trapped water splits the spigot |
| Interior spigot valve | Close and drain the outdoor side | Keeps the pipe empty |
| Sprinkler zones | Drain or blow out | Frozen lines crack |
| Backflow assembly | Drain and protect | A frozen body can crack |
Timing
Fall freezes along the Front Range can come before the first snow. Do the work by mid-October when you can, and watch the forecast for a hard freeze.
Do not wait for the first frost. A single night can crack a full assembly.
Spring startup
Open valves slowly to avoid shock. Check each zone for leaks, broken heads and stuck valves. Look at the backflow assembly for drips and book its annual test.
Run the system on a mild day so you can see problems before the heat of summer.
When to call a plumber
Call if a spigot leaks inside the wall, if the backflow assembly is cracked or if the sprinkler line is split. A plumber can repair the pipe and replace the spigot or assembly.
If a frozen pipe bursts, close the main valve first and call for repair.
A simple fall routine
Pick a weekend in early autumn and work through the list. Coil and store hoses, remove splitters and timers, and drain the spigot after closing its interior valve. Cover exposed spigots with an insulated cap only after draining them.
Look at the sprinkler controller too. Switch it to rain or off mode after the blowout so it does not try to run in winter. Turn off the supply to the sprinkler system and open the drain valves at low points.
Signs of winter damage in spring
When you turn the water back on, watch closely. Low pressure, a wet spot near the foundation or a hissing sound from inside a wall can mean a pipe split during the winter. Check the basement ceiling near the spigot for stains.
On the irrigation side, geysers, soggy patches and zones that do not come on suggest cracked heads or lines. Mark the problem areas with flags so the repair crew can find them quickly.
Why professionals blow out the lines
A compressor needs the right pressure and a careful hand. Too much air can crack fittings and heads, while too little leaves water behind. A trained technician works zone by zone and avoids overpressurizing the system.
If you do the blowout yourself, wear eye protection, stay clear of the heads and use a regulator. Do not run a zone for long with only air, because the heads can overheat. When unsure, hire the job out.
Questions to ask a sprinkler contractor
Ask whether they blow out each zone separately and how they set the compressor pressure. Ask if the visit includes draining the backflow assembly and shutting off the supply, or whether those steps are extra.
Request a note of any problems they find, such as broken heads, leaking valves or damaged lines. Fixing those in the fall is easier than hunting for them in spring.
Book early. Contractors fill up fast after the first cold forecast, and a late freeze can crack lines before the crew arrives.
Extra protection for exposed pipes
Pipes in a garage or a crawlspace that reach outdoor spigots can freeze even when the spigot is drained. Wrap them with foam sleeves and seal gaps where they pass through the wall. A small amount of insulation prevents big repairs.
Leave a note with your winterizing date and the location of each shutoff. Next fall you will repeat the same routine without hunting for valves, and a house sitter or family member can follow it if you are away.
Hose bibs that hide a problem
A frost-free spigot extends into the house so the valve seat stays warm. It still must be drained: remove the hose, and make sure the spigot tilts slightly downward so water runs out. A hose left attached can trap water and defeat the design.
If a spigot drips after you close it, the washer or the stem is worn. Replace it before winter, since a constant drip can freeze into the pipe and split it.
Common questions
Answers about winterizing
Before the first hard freeze. In this area, many owners do it in October, but watch the forecast.
The hose must still come off. Water left in the hose can freeze and back up into the barrel.
A certified backflow tester. Westminster requires annual testing and reporting for assemblies on its water service.
Close the interior valve and call. A split pipe behind a wall needs repair.
Related services
Frozen Pipe Repair & Thawing
Thaw an iced-up line safely, inspect it for splits and reroute or insulate the run that keeps freezing.
Faucet & Sink Repair
Cure dripping taps, weak streams, seized shutoff valves and leaking hose bibs.
Keep reading
Frozen pipes: thaw safely and prevent a repeat
A frozen pipe can split the moment it thaws. Here is how to warm it safely, what to check afterward and how to keep it from freezing again.
Shutting off the main water valve
Know where the main valve is before you need it. This guide covers where to look, how to turn it and what to do if it sticks.
Reasons your water bill jumped
A bill that suddenly climbs normally traces back to just a few culprits. Check the meter, the toilets and the sprinkler before you call.
Spigot leaking or pipe split?
Close the interior valve and call. The dispatcher then matches you with a nearby contractor.