For most homes, a good rule of thumb is to start dripping faucets when the outside temperature is expected to drop to around 20°F −6.5°C-6.5°C−6.5°C or lower for several hours, and to keep them dripping as long as it stays below about 20°F.

Key temperature guidelines

  • Begin dripping indoor faucets if:
    • The forecast shows 20°F or below for 3+ hours , or
    • It will be below freezing and your home is older, poorly insulated, or has pipes on exterior walls.
  • Keep faucets dripping until:
    • Temperatures stay above 20°F , and
    • You’ve checked that water runs normally from all fixtures (no slow flow that might indicate partial freezing).

How much to drip

  • Aim for a slight trickle , not a full stream:
    • Roughly one drop every few seconds or a very thin continuous thread of water.
  • In extreme cold (near 0°F or below), increasing the drip to a very small steady stream offers extra safety, especially for vulnerable pipes.

Which faucets to drip

  • Prioritize:
    • Faucets on exterior walls.
    • The faucet farthest from your water meter , so water moves through the longest portion of your plumbing.
  • If your area is facing an extended hard freeze or you know you have poorly insulated pipes , dripping multiple faucets (hot and cold) is safer.

Extra frozen-pipe protection

  • Keep your home’s heat at 55°F or higher during a freeze, even at night or when away.
  • Open cabinet doors under sinks on exterior walls so warm air can reach the pipes.
  • Insulate exposed pipes and cover outdoor spigots; shut off and drain garden hoses and exterior faucets if possible.

Quick TL;DR

  • Start dripping at about 20°F and below , sooner if your house or pipes are vulnerable.
  • Use a small drip or thin trickle , not a heavy stream.
  • Focus on exterior-wall and farthest-run faucets , and keep indoor heat on with cabinet doors open under sinks.

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