Flagstaff is one of the snowiest cities in the contiguous United States. We average around 100 inches of snowfall a year, our overnight lows drop into the teens and single digits from October through April, and at 6,910 feet of elevation, freezing temperatures are not unusual even in May. That climate is hard on plumbing — especially on homes that were not built or upgraded with cold weather in mind.
The good news is that frozen and burst pipes are largely preventable. Here are seven tips every Flagstaff homeowner should know before the first hard freeze.
The pipes most at risk in Flagstaff are the ones in unheated or poorly insulated spaces. Foam pipe insulation sleeves are cheap, easy to install, and dramatically reduce freeze risk. Pay particular attention to pipe runs in crawlspaces, along exterior walls, in unheated garages, and through unconditioned attics. Older homes in neighborhoods like Sunnyside, Greenlaw, and Cheshire often have exposed copper or galvanized lines that benefit most.
Heat tape (also called heat cable) is a thermostatically controlled electric cable that wraps around a pipe and turns on automatically when temperatures drop. For pipes that have frozen before, or pipes you simply cannot insulate well, heat tape is the answer. Use only UL-listed, self-regulating cable, follow the installation instructions exactly, and plug it into a GFCI outlet. Heat tape installed wrong can be a fire hazard.
Standard outdoor hose bibs are a common burst point in Flagstaff. The valve sits right at the wall, where it is exposed to freezing temperatures. A frost-free (also called freeze-proof) hose bib has a long stem that places the actual shutoff valve inside the heated wall cavity, well away from outdoor air. Replacing your hose bibs with frost-free versions costs a few hundred dollars and pays for itself the first time you avoid a wall-cavity burst.
Even with a frost-free hose bib, a connected garden hose can trap water against the valve and cause a freeze-up. Before the first hard freeze (typically October in Flagstaff), disconnect every garden hose, drain it, and store it inside. Same goes for any drip irrigation or in-ground sprinkler system — blow them out and shut off the supply.
Cold air entering a crawlspace through open vents is one of the biggest contributors to frozen pipes in Flagstaff homes. Most building codes now call for sealed crawlspaces in our climate zone, but many older homes still have open vents. At minimum, close them off for the winter with foam vent covers. Better yet, talk to a contractor about insulating and conditioning the crawlspace year-round. Seal gaps where pipes pass through the rim joist as well.
If you leave town in winter, do not turn your heat all the way down. Set the thermostat no lower than 55°F so interior temperatures stay above freezing even during a cold snap. If you are leaving for an extended trip in winter, consider shutting off the main water valve and draining the system entirely — that way a burst pipe cannot cause damage while you are away. Owners of seasonal cabins in Munds Park and Forest Highlands should treat winterization seriously.
When forecasts call for overnight lows in the single digits or below zero, take two extra steps. Open the cabinet doors under sinks on exterior walls so warm room air can reach the pipes. And let a thin stream of cold water run from the faucet farthest from the supply entry. Moving water resists freezing, and an open faucet relieves pressure if ice does start to form. These small habits prevent a lot of January and February emergency calls.
If you turn on a faucet and only a trickle (or nothing) comes out, you likely have a frozen pipe. Here is what to do:
Flagstaff Plumbing Pros offers 24/7 emergency service for frozen and burst pipes. Call (555) 000-0000 any time.
Pipes typically start to freeze when the ambient temperature around them stays below about 20°F for several hours. In Flagstaff, that happens routinely from late October through April thanks to our 6,910-foot elevation. Pipes in unconditioned spaces like crawlspaces, exterior walls, unheated garages, and attics are most at risk. Interior pipes in heated living space are usually safe unless you lose heat for an extended period.
Yes, during severe cold snaps in Flagstaff (overnight lows in the single digits or below zero) it is a good idea to let a thin stream of cold water run from the faucet farthest from where the supply line enters your home. Moving water is much harder to freeze than standing water, and the open faucet relieves pressure if ice does start to form. A pencil-thin stream is enough.
First, do not use an open flame to thaw the pipe — propane torches and heat guns cause structure fires every Flagstaff winter. Shut off the main water valve in case the pipe has cracked. Open the affected faucet so water can flow when the ice melts. Apply gentle heat with a hair dryer, heating pad, or space heater starting from the faucet side and working back toward the frozen section. If you cannot locate the frozen section, cannot access it safely, or you suspect a burst, call a plumber. We have proper thawing equipment and can repair burst sections on the spot.