If you’ve turned on the tap and nothing comes out during a cold snap, you likely have a frozen pipe. The right move right now is to shut off your main water valve, then watch for signs the pipe has already cracked while you wait for a licensed plumber to assess the damage.
Why Pipes Freeze (and Where to Look First)
Water expands when it freezes. That expansion builds pressure inside the pipe until something gives, so speed matters.
The pipes most likely to freeze are the ones closest to the cold: exterior walls, unheated crawl spaces, garages, and any supply line that runs through an uninsulated cavity. In Bay Area homes, common culprits are the cold-water line under a kitchen sink on an exterior wall and hose bib supply lines that run through the garage. Attic supply runs are a surprise candidate too, especially in older homes where insulation was never added above the pipe.
Find Your Main Shut-Off and Turn It Off
Do this before anything else. If the pipe has already cracked, water will flow the moment the ice melts. Knowing where your shut-off is saves you a flooded subfloor.
Most single-family homes in California have the main shut-off at one of three spots: near the water meter at the street (usually in a covered box at the curb), at the perimeter of the house near the foundation, or inside the garage. It’s either a gate valve (round wheel handle) or a ball valve (flat lever). Ball valves close with a quarter-turn perpendicular to the pipe. Gate valves take several full rotations.
If you can’t find it, call your water utility. They can tell you where it is, and in some cases send someone out.
Signs the Pipe Has Already Burst
A frozen pipe that cracked may not show it until the ice melts. Watch for:
- A visible bulge or deformation anywhere on the pipe
- Water stains or wet drywall near the suspected section
- Dripping from a ceiling or wall when you crack the main shut-off slightly to test
If you see any of those, keep the main valve off and call a licensed plumber. Cutting out the damaged section and fitting a replacement requires a California plumbing contractor license (C-36).
What to Do While You Wait
Shutting off the main water valve is the most important thing you can do. Beyond that, if you have an exposed pipe under a sink that you can see and reach, some people warm it gently with a hair dryer on medium (not high) heat. Keep the faucet open so water has somewhere to go as the ice releases, and keep the dryer moving.
What not to do: any open flame, including a propane torch. Torching a frozen pipe is a known cause of house fires. Skip heat guns on high power and boiling water poured directly on the pipe for the same reason.
If the pipe is inside a wall, ceiling, or slab, don’t attempt to access it. That’s a job for a licensed plumber with the right tools.
When to Call a Licensed Plumber
Call rather than continuing to wait it out if:
- You can’t locate the frozen section or can’t access it safely
- The pipe is inside a wall, ceiling, or slab
- There’s any evidence of cracking or leakage
- The pipe is plastic (PEX or CPVC) and shows visible distortion
- You’ve been at it a while with no sign of water flowing
Even a pipe you successfully thaw yourself is worth having a plumber inspect afterward. A line that froze once is usually poorly insulated and will freeze again, and repeated freeze-thaw cycles fatigue both metal and plastic over time. A licensed plumber can confirm no damage was done, locate where insulation is missing, and recommend a permanent fix.
This site is an information resource only. We do not hold a plumbing license and do not offer plumbing services. To find a licensed plumber in California, verify their license at cslb.ca.gov before hiring. Confirm the license is current and covers plumbing work (C-36).
Prevention for Next Time
Once the immediate situation is resolved, the fix for a pipe that freezes repeatedly is insulation. Pre-slit foam pipe insulation is inexpensive and widely available at hardware stores, and it installs in minutes on accessible pipe. For pipes inside exterior walls, a plumber or insulation contractor can assess whether blown-in insulation makes sense.
Keeping cabinet doors under exterior-wall sinks open during a cold snap lets warm room air reach the pipes. A slow overnight drip from an affected faucet reduces the chance of refreezing by keeping water moving, though it’s not a substitute for fixing the underlying insulation problem.
Andrew Kuznetsov is the owner of Bay Area Plumbing Service. This guide is for informational purposes only. For any pipe repair, hire a licensed plumber and verify their California contractor license at cslb.ca.gov.