You generally want to start letting faucets drip when the outside temperature is around 20°F (about −6°C) or lower, especially if it will stay that cold for several hours overnight.

Key temperature guidelines

  • Many plumbers and home guides recommend dripping faucets when the forecast shows 20°F or below for several hours (often 3–6+ hours), because that’s when pipes are at higher risk of freezing.
  • Some homeowners in older or poorly insulated houses start a bit earlier, around 25–28°F , if those temps are expected to last through the night.
  • Keep faucets dripping until temperatures are safely above freezing (32°F / 0°C) and staying there , not just for a brief afternoon warm‑up.

How much to drip

  • A slight trickle is usually enough: roughly one or two drips per second or a thin stream about the width of a pencil lead.
  • In extreme cold (close to 0°F or below), some utilities and plumbers suggest increasing to a small but steady stream to be safer.

Which faucets to drip

  • Prioritize faucets on exterior walls and those farthest from where water enters the home, since those runs of pipe tend to be coldest and most vulnerable.
  • Many pros suggest dripping both hot and cold sides so neither line freezes, especially if you’ve had issues with hot lines freezing before.

Other key tips

  • Try to keep your home’s heat at about 55°F or higher , even if you’re away.
  • Open cabinet doors under sinks on exterior walls so warm air can reach the pipes.
  • Insulate exposed pipes with foam insulation or heat tape , and shut off and drain outdoor spigots and hoses.

Quick example

If the forecast says tonight will be 18°F from midnight to 8 a.m. , you’d typically:

  1. Set the thermostat to at least 55°F.
  1. Open sink cabinets on exterior walls.
  1. Turn at‑risk faucets on to a light drip (both hot and cold where possible) before bed and leave them dripping until the temperature is back above freezing for a while the next day.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.