Short definition

Dripping a faucet during a freeze means opening the tap to a slow, steady trickle so water keeps moving through the supply line. Moving water is harder to freeze than still water, and the open faucet relieves pressure if the line does ice up — which prevents the burst. In Washington, drip a few of the most distant fixtures (both hot and cold sides) when overnight lows are forecast below about 25 °F.

What it is

The drip strategy works for two reasons. First, water flowing through a pipe — even at a trickle — carries heat from the warm parts of the system into the cold sections, slowing freeze formation. Second, an open faucet is a pressure-relief path: if an ice plug starts to form, the trapped water can escape forward through the open tap rather than rupturing a fitting downstream.

Standard practice in WA cold snaps:

  • Open the cold-water tap at the farthest fixture from where the supply enters the house — usually a kitchen sink, an upstairs bathroom, or a basement laundry tap. This pulls water through the longest run of vulnerable pipe.
  • Drip the hot side too, because the hot-water branch can freeze independently.
  • Aim for a pencil-lead trickle — about a continuous strand, not separate droplets. Drops alone can freeze in the basin without keeping flow in the line.
  • Open cabinet doors under sinks on exterior walls so house heat reaches the supply lines.

A pencil-lead drip uses roughly 5 gallons over 24 hours per fixture — about $0.05–$0.20 per night in WA water-and-sewer rates. Cheap insurance compared to a $5,000 burst.

Why it matters to a homeowner

For an occupied WA home, dripping is the simplest, most universally recommended freeze-night practice — covered in PSAs from PSE, SPU, Tacoma Power, the American Red Cross, and every local TV news weather segment when a freeze hits. The message is consistent because it works.

The trap most homeowners fall into is closing the drip overnight to “save water” and waking up to a burst pipe. Cold-snap freezes typically hit between 2:00 AM and 8:00 AM, exactly the hours people would otherwise turn the tap off. If the forecast says hard freeze, leave the drip running until daytime temperatures have been above freezing for several hours.

Dripping is supplementary — not a substitute for insulating exposed pipes, adding heat tape on known-vulnerable runs, or winterizing a vacant home. Layered protection is what prevents bursts.

When to use this strategy

  • Forecast hard freeze — 25 °F or lower overnight, especially multi-night cold snaps
  • East-wind events in Puget Sound — the wind chill drops effective pipe temperatures faster than air temperature alone
  • Older WA home with copper supply in exterior walls or uninsulated crawlspace
  • Single-night freeze when other prep wasn’t done — drip is the fastest mitigation
  • Power outage during a freeze — drip works without electricity (heat tape doesn’t)

Common failure modes

  • Drip too small. Water freezes in the faucet itself; flow stops without you noticing; main line freezes anyway. A continuous strand, not separate drops.
  • Drip closed overnight to save water. Freeze hits during the unprotected hours.
  • Cold-only drip. Hot-water branch freezes; tank pressure spikes; relief valve trips or the hot branch bursts.
  • Wrong fixture chosen. Dripping an interior bathroom while the actual at-risk run is in a crawlspace under the kitchen.
  • Dripped faucet but no insulation. In a sustained sub-20 °F event, drip alone is not enough on uninsulated runs.

Common variants and disambiguation

  • Drip the faucet (occupied home, brief cold snap) vs. winterize / drain (vacant home, extended cold) — different strategies for different situations.
  • Drip the cold vs. drip both sides — practical advice in WA is both.
  • Drip an indoor faucet vs. drip an outdoor sillcock — only drip an outdoor spigot if you’ve not already shut off and drained the outdoor branch for winter.

Washington note

WA utilities have built drip-faucet guidance into their standard cold-weather PSAs. The January 2024 freeze drove this messaging across PSE, SPU, and Tacoma Power outreach: drip faucets, leave heat at minimum 55 °F, know your main shutoff. Local news weather coverage repeats the same checklist any time the forecast turns cold.

WA water rates make the marginal cost of a multi-night drip negligible — a few dollars total — even in jurisdictions with combined water-and-sewer billing. There’s no realistic scenario where dripping costs more than the bursts it prevents.