Direct answer: If your kitchen sink stops running or stops draining during a cold snap, the usual cause is a frozen section in the supply line, the drain trap, or the pipe run in an exterior wall or cabinet. Start by figuring out whether no water is coming out, water is backing up, or you already see a leak.
Most likely: Most often, the freeze is in the kitchen sink supply line or drain line where it passes through a cold exterior wall, uninsulated sink base, crawl space, or basement ceiling near the outside wall.
A frozen kitchen sink line is usually pretty obvious once you separate the lookalikes. No flow at the faucet points to a frozen supply line. Standing water that will not leave points more toward a frozen drain or trap. Water stains, bulging pipe, or dripping after thawing raise the stakes because a split may already be there. Reality check: the frozen spot is often several feet away from the sink, not right under it. Common wrong move: heating one tiny visible section while the real ice plug is still buried in the wall or crawl space.
Don’t start with: Do not start with a torch, open flame, boiling water on plastic piping, or hard cranking on shutoff valves that have been sitting in the cold.
The faucet handle moves normally but little or no water comes out, while other fixtures may still work.
Start here: Check whether nearby faucets still have water so you can tell if this is a local kitchen sink supply freeze or a larger house-wide problem.
One side of the kitchen faucet flows and the other side is dead or just dribbles.
Start here: Focus on the frozen branch serving that side, usually where that line runs through a cold wall, cabinet, basement rim area, or crawl space.
Water backs up and sits in the bowl, often after a very cold night, even though the faucet still runs.
Start here: Look at the trap and exposed drain piping under the sink first, then think about the drain run in the wall or floor.
You see dripping, spraying, or a damp cabinet floor once the line warms up.
Start here: Shut off the local or main water supply and treat it as a split kitchen sink pipe until proven otherwise.
This is the most common setup when the faucet suddenly stops during a cold snap, especially at sinks on outside walls.
Quick check: Open the kitchen faucet and see whether both hot and cold are dead or only one side is affected. Then feel for very cold pipe sections in the sink base, basement below, or crawl space near that wall.
If the faucet still runs but the sink will not empty in freezing weather, the drain side is the better fit than a supply problem.
Quick check: Look under the sink for frost on the trap, a very cold metal or plastic trap, or a drain line that runs through a cold cabinet, wall, or floor cavity.
A cabinet that feels like outside air can freeze pipes even when the rest of the kitchen is comfortable.
Quick check: Check for missing insulation, open holes around pipes, loose toe-kick gaps, or a cabinet against an exterior wall that feels much colder than the room.
A pipe often splits while frozen and only starts leaking once it thaws and pressure returns.
Quick check: Look for bulges, hairline cracks, fresh drips, cabinet swelling, or water showing up below the sink or in the basement ceiling after thawing starts.
You do not want to thaw the wrong thing or miss a split pipe that will dump water once pressure comes back.
Next move: If you clearly identify one dead supply line, a blocked drain, or an active leak, move to the matching next step instead of guessing. If multiple fixtures are dead or pressure is poor all over the house, this is likely beyond the kitchen sink branch and needs a broader frozen pipe check.
What to conclude: A kitchen-only problem usually points to a local branch line or drain near that sink. A leak means the job changes from thawing to water control and repair.
The safest first thaw is simple room heat and airflow. It often works when the frozen section is close to the cabinet or wall cavity.
Next move: If flow slowly returns or the drain starts moving again, keep the area warm and continue with inspection before calling it done. If nothing changes after the cabinet and room have warmed, the frozen section is probably farther along the pipe run in the wall, floor, basement, or crawl space.
What to conclude: A quick recovery usually means the freeze was near the sink base. No change points to a hidden colder section farther away.
Kitchen sink lines usually freeze where they pass through the coldest part of the run, not at the faucet body itself.
Next move: If you find the cold section, you can focus gentle heat there while keeping the faucet slightly open or the drain clear of added water. If the line disappears into a finished wall or inaccessible cavity and the kitchen still has no service, the safest next move may be a plumber with thawing equipment and leak-repair readiness.
Slow thawing is safer for the pipe and gives you time to catch a split before it becomes a flood.
Next move: If water flow or drainage returns and no leaks appear, let the line fully thaw, then move straight to verification and prevention. If the pipe stays blocked, the frozen section is inaccessible, or a leak appears, stop thawing and plan for repair or a plumber visit.
Once the pipe tells you which path you are on, act on that result instead of waiting for the next freeze to repeat it.
A good result: If the line holds pressure, drains normally, and stays dry after several uses, the immediate problem is solved.
If not: If the pipe leaks under pressure, the drain leaks while emptying, or the freeze keeps coming back in the same weather, the repair is incomplete and the cold exposure still needs attention.
What to conclude: A clean thaw calls for prevention. A split line calls for actual pipe repair before normal use resumes.
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If the faucet will not deliver water, think frozen supply line first. If the faucet runs but the sink stays full, think frozen drain or trap first. A normal clog is less tied to weather and usually does not show up right after a hard freeze.
Warm water may help a lightly frozen metal trap, but do not dump boiling water into a frozen drain, especially if plastic piping is involved. Sudden heat can crack parts or just add more standing water if the line is still blocked.
That usually means one branch line froze while the other stayed open. Follow the dead side's supply line through the cabinet, wall, basement, or crawl space and look for the coldest exposed section.
Usually not as a close-range fix inside a cabinet. A hair dryer with moving heat is safer for short, attended thawing on accessible piping. If you use any room heater nearby, keep it outside the cabinet, away from combustibles, and never leave it unattended.
Shut off the local sink valves or the main water supply right away. Once a frozen kitchen sink pipe leaks, the job is no longer thawing. It is now a pipe repair, and hidden leaks behind walls or below floors are a good reason to call a plumber.
Sometimes, but not always. Insulation helps most when the pipe is exposed and the main problem is heat loss. If cold air is blowing into the cabinet or the pipe runs through a very cold cavity, you also need to seal drafts and keep that area warmer.