Should I Let a Faucet Drip Until the Weather Goes Above Freezing?
As winter temperatures plummet, homeowners often face the dilemma of whether or not to leave their faucets dripping. While it may seem like a waste of water, this simple preventative measure is one of the most effective ways to avoid the catastrophic expense of a burst pipe. But do you need to keep it running until the weather is completely above freezing?
The Science: Why a Dripping Faucet Prevents Bursts
Contrary to popular belief, a dripping faucet does not prevent a pipe from freezing because the water is "moving." Instead, it works by relieving pressure. When water freezes in a pipe, it expands. This expansion creates immense pressure between the ice blockage and the closed faucet. By leaving the faucet slightly open, you provide a relief valve for that pressure. Even if the water freezes, the pipe is far less likely to burst because the pressure has an escape route.
When Exactly Should You Start Dripping?
You do not necessarily need to drip your faucets the moment the temperature hits 32?F (0?C). Most plumbing experts and the Red Cross recommend the following thresholds:
- The 20-Degree Rule: Most pipes are at risk when the outside temperature drops to 20?F (-6?C) or below, especially if the pipes are located in uninsulated areas like attics, crawlspaces, or exterior walls.
- Wind Chill Factor: If high winds are present, the "feel-like" temperature can push cold air into small gaps in your siding, reaching pipes faster. In these cases, start dripping earlier.
- Duration of Freeze: A quick dip below freezing for an hour usually isn't enough to freeze a pipe inside a wall. However, if the temperature stays below 28?F for more than 4?6 hours, the risk increases significantly.
Should I Keep it Dripping Until it's Above 32?F?
The safest practice is to keep the faucets dripping until the air temperature consistently stays above freezing (32?F) and the sun has had a chance to warm the exterior walls of your home. If your pipes are in a crawlspace, that area stays colder longer than the outside air. It is often wise to wait until the "High" for the day reaches at least 35?F before turning the faucets off.
How Much Water is Necessary?
You don't need a steady stream; a slow drip (about 5 to 10 drops per minute) is usually sufficient to relieve pressure.
- Choose the faucet furthest from the water main.
- Focus on faucets served by pipes running through exterior walls.
- Drip both the hot and cold lines, as both are susceptible to freezing.
Other Critical Steps to Prevent Frozen Pipes
While dripping is helpful, it shouldn't be your only line of defense. Consider these home improvement steps:
- Open Cabinet Doors: Allow warm air from the room to circulate around the pipes under your kitchen and bathroom sinks.
- Seal Gaps: Use spray foam or caulk to seal holes where pipes enter the home through exterior walls.
- Keep the Heat On: Never set your thermostat below 55?F (13?C) when leaving the house during winter.
- Disconnect Hoses: Remove garden hoses from outdoor spigots to allow the faucet to drain properly.
Conclusion: Small Drip, Big Savings
Letting a faucet drip during a deep freeze is a minor inconvenience compared to the thousands of dollars in water damage and plumbing repairs caused by a burst pipe. If the forecast calls for temperatures sustained below 20?F, keep those faucets dripping until the mercury rises safely above the freezing mark. Your plumbing?and your wallet?will thank you.
