For most homes, faucets should be dripped when outside temperatures are expected to drop to around 20°F (about -6.5°C) or lower for several hours, especially overnight.
When to drip
In many plumbing and insurance guides, 20°F is cited as the point where typical residential pipes are at higher risk of freezing, so dripping faucets at or below this temperature is a common recommendation. Some home repair sources also suggest dripping if it will stay below 32°F (0°C) for several hours, particularly in older homes or where pipes are in exterior walls or uninsulated spaces.
How much to drip
A very small, steady trickle is usually enough, such as one or two drops every few seconds or a thin stream about the width of a pencil lead, which keeps water moving while limiting waste. If temperatures approach 0°F or your home has known problem areas, increasing the drip slightly can add extra protection.
Extra precautions
Drip both hot and cold sides, or set a single-handle faucet in the middle so both hot and cold lines flow a bit. Also keep indoor heat at roughly 55°F or higher and open cabinet doors under sinks on exterior walls so warm air can reach the pipes.
