When and How to Drip Faucets During Cold Snaps
A pencil-thin stream of water costs pennies and prevents thousands of dollars in damage. But knowing when to drip, which faucets to drip, and how much to drip separates people who stay dry from people who wake up to flooded kitchens. Below 20°F, this five-minute habit is the cheapest insurance you will ever buy.
Quick Summary
Time Required
5 minutes per cold snap
Difficulty
Easy
Cost
$1–$2 in water per event
The 20°F Threshold
Temperature is the primary trigger. Know when to start dripping and when you can stop.
- Drip at forecast lows of 20°F or below: Even for a few overnight hours. Pipes in exterior walls get colder than ambient air.
- Drip earlier if wind chill is severe: Cold air moving through wall cavities cools pipes faster. Wind chill of 0°F or below warrants dripping even at 25°F air temperature.
- Drip for sustained events: A single 2°F hour before dawn is less risky than 24 hours of 18°F. Multi-day cold snaps need dripping even if daytime temps rise above freezing.
- Drip on at-risk pipes, not all pipes: Pipes inside the heated envelope away from exterior walls do not need dripping. Focus on exterior-wall fixtures.
- Stop when temps rise above 30°F: Once outdoor lows stay above freezing, turn off the drips. Continued dripping wastes water without benefit.
Which Faucets to Drip
Not all faucets need protection. Focus on the ones most vulnerable to freezing.
Kitchen sinks on exterior walls
Kitchens on outside walls typically have supply pipes running through cold wall cavities. These are classic freeze locations and should be your first drip target.
Bathrooms on exterior walls
Especially bathrooms with plumbing on north-facing walls. Both the sink and bathtub supply lines run through the same cold cavity.
The faucet furthest from the water heater
The hot water line that runs the longest distance cools most between uses. Dripping the farthest hot faucet keeps water flowing through that entire line.
Garage or basement utility sinks
Fixtures in unheated or barely-heated spaces are always at risk. If you have a utility sink in an attached garage or cold basement, drip it during every freeze event.
The Pencil-Lead Flow Rate
Too little flow does not help; too much wastes water and money. The target is a steady stream the thickness of a pencil lead.
- Not drops: Slow drips every few seconds are not enough to keep water moving through the full pipe run. Slow drips also refreeze easily at the aerator.
- Not a stream: A visible solid stream wastes gallons per hour. A bathtub fills in a few hours at this rate.
- About 1–2 millimeters thick: Look at a standard pencil lead. The water stream should match that thickness as it falls from the faucet.
- Both hot and cold: Open both valves so both supply lines stay active. Dripping only cold leaves hot water stagnant and at risk.
- Steady, not pulsing: The stream should be continuous. Air bubbles or pulsing means the valve is too open or too closed.
Pair Dripping with Other Protections
Dripping alone is not enough for severe cold. Combine it with other measures for full protection.
Open cabinets on exterior walls
Warm room air needs to reach pipes inside wall cavities. Dripping and open cabinets together are far more effective than either alone.
Keep heat at 55°F or higher everywhere
No room should fall below 55°F. Heat on, all doors and vents open, no exceptions during a cold snap.
Add a space heater to problem areas
For pipes in basements, garages, or bonus rooms, a small oil-filled space heater on low adds direct warmth. Pair with dripping for belt-and-suspenders safety.
Pro Tips
- •Drain to a bathtub drip: If your bathtub has a faucet and drain that will not plug, drip into it instead of a sink. Easier to maintain a slow flow over a tub drain.
- •Plug sinks with drips going in: Instead of losing water to the drain, plug the sink and save the water to wash dishes or water plants. Zero waste.
- •Check faucets at 2 AM if you can: The coldest hour is usually just before dawn. Confirm drips are still flowing—aerators can clog and stop the drip without you noticing.
- •Consider a smart freeze monitor: Wireless temperature sensors in at-risk areas alert your phone if temps drop below a threshold. $20–$40 and well worth it.
Frequently Asked Questions
Why does dripping a faucet prevent freezing?
Moving water resists freezing in two ways. First, the movement itself disrupts ice crystal formation—static water freezes much faster than flowing water. Second, and more importantly, dripping relieves pressure buildup in the line. Even if ice forms, the pressure between an ice plug and a closed faucet is what actually bursts pipes. An open faucet gives pressure somewhere to go, so even a fully frozen pipe may not crack. Prevention and damage limitation happen at once.
How much water does dripping waste?
A pencil-lead stream wastes about 10–15 gallons per faucet over 12 hours, costing roughly 5–10 cents. Dripping multiple faucets for 3–4 nights during a cold snap adds up to $1–$2 per cold snap. Compare that to a single burst pipe's average insurance claim of $5,000–$25,000 and the cost is irrelevant. Only drip faucets you actually need to protect—pipes well inside the heated envelope do not need it.
Should I drip faucets at every freeze or only extreme cold?
The 20-degree threshold is a guideline, not a hard rule. Consider dripping earlier if your home has a history of frozen pipes, if you are in a historically warm area where homes are not well-insulated for freeze events, if you have pipes in an unheated garage or crawl space, or if the cold snap will last more than 24 hours. Homes in routinely cold climates with proper construction may never need to drip. When in doubt, drip—the cost is trivial and the protection is real.
Related Guides
Winter Maintenance Checklist
Complete 20-step guide to staying comfortable and safe all winter
Prevent Frozen Pipes
Protect pipes with heat, insulation, and air sealing before the first freeze
Identify and Thaw Frozen Pipes
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Maintain Your Home Humidifier
Keep indoor humidity in the 30–40% sweet spot through heating season