Short answer: Drip your faucets when the overnight forecast drops below freezing, especially if it’s headed to 20°F or colder, or if a cold east wind is blowing. Pick the faucets on outside walls or above crawlspaces, and let a slow, steady drip of cold water run until temperatures climb back above freezing.
Portland doesn’t get many freezing nights. But when we do, they tend to come in a bunch, and pipes in older homes, crawlspaces, and garages feel it fast. Here’s everything you need to know about when to drip faucets, which ones, and how much.
What Temperature Should You Drip Your Faucets?
Start dripping when the overnight low is forecast to drop below 32°F. That’s what the Portland Water Bureau recommends, and it’s the safe call for most homes around here.
You’ll often hear 20°F as the magic number. That’s a common rule of thumb for pipes inside a well-insulated, heated house. But many Portland-area homes have pipes running through crawlspaces, garages, and outside walls with little or no insulation. Those pipes can freeze well before it hits 20°F.
Does Wind Make a Difference?
Yes, a big one. When a cold east wind blows out of the Columbia Gorge, it pulls heat out of your walls and crawlspace much faster. A windy night in the mid-20s can be harder on your pipes than a calm night that’s colder.
Should I Drip My Faucets Tonight?
Ask yourself three things:
- Is tonight’s low below freezing?
- Is it supposed to stay below freezing for more than a few hours?
- Do you have pipes in a crawlspace, garage, or along an outside wall?
If you answered yes to the first question and either of the others, drip your faucets tonight. When in doubt, drip. A night’s worth of water costs far less than fixing a burst pipe.
Why Does Dripping a Faucet Keep Pipes From Freezing?
Dripping helps in two ways. First, moving water is harder to freeze than water that’s sitting still. Second, and more important, an open faucet lets pressure escape.
Here’s why that matters. When water starts to freeze, the ice pushes the water ahead of it down the pipe. If the faucet is closed, that water has nowhere to go, and the pressure builds until the pipe splits. A dripping faucet gives that pressure a way out.
That’s also why pipes often burst somewhere other than where the ice is. The crack shows up where the pressure builds, between the ice and the closed faucet.
Which Faucets Should I Drip, and How Many?
Drip the faucets whose pipes are most likely to get cold. For most homes, that’s one to three faucets, not every one in the house. Look for:
- Sinks on an outside wall, like a kitchen sink under a window
- Bathrooms above a crawlspace or over an unheated garage
- Laundry sinks in a garage or unheated basement
- The faucet farthest from where water enters your house, so water moves through as much pipe as possible
If your house is on the bigger side or has pipes in a few different cold spots, drip one faucet at each end of the house.
Should I Drip My Outside Faucets?
No. Outside faucets need a different plan: unhook the hose, shut off the valve inside, and drain the faucet. A dripping outdoor faucet can ice over and still freeze. Our guide to frozen outdoor faucets walks you through it.
How Much Should I Drip My Faucets?
A slow, steady drip is enough, about one or two drops per second. You don’t need a stream. The goal is to keep the faucet open so pressure can escape, not to run water through the whole house.
Should I Drip Hot or Cold Water?
Cold. The Portland Water Bureau recommends dripping cold water, and it keeps your water heater from running all night. On a single-handle faucet, push the handle all the way to cold.
The one exception: if a sink’s hot water pipe also runs along a cold outside wall, open the hot side a crack too. With two handles, drip both. With one handle, set it in the middle.
Is It OK to Drip a Faucet Into a Slow Drain?
Check first. If a sink drains slowly, a drip running all night can fill it up and spill over. Pick a different faucet, or get the drain cleared before the cold weather hits.
What Else Can I Do to Keep Pipes From Freezing?
Dripping works best alongside a few other simple steps:
- Open cabinet doors under sinks on outside walls so warm air reaches the pipes.
- Keep your heat on, even at night. If you’re leaving town, set the thermostat no lower than 55°F.
- Close or cover crawlspace vents during a cold snap. Open them again once it warms up.
- Wrap exposed pipes in crawlspaces, garages, and attics with foam pipe sleeves from the hardware store.
- Unhook garden hoses and cover outside faucets.
- Find your main water shutoff now, before you need it, so you can turn the water off fast if a pipe breaks.
Why Do Pipes Burst After the Freeze Ends?
A frozen pipe often cracks during the freeze but doesn’t leak until the ice melts. That’s why so many leaks show up as things warm back up. During the January 2024 thaw, the Portland Water Bureau answered more than 1,250 calls in four days. Keep dripping until the temperature is solidly above freezing, then check under sinks and in your crawlspace for water.
What if a Pipe Freezes Anyway?
If you turn on a faucet and get nothing, or just a trickle, the pipe feeding it is probably frozen. Leave that faucet open. Then gently warm the pipe with a hair dryer, starting near the faucet and working back. Never use a torch, a propane heater, or any open flame.
If you see water spraying or leaking, shut off your main water valve right away. The Water Bureau also suggests turning off your water heater so it doesn’t keep pulling water into a broken pipe.
When Should I Call a Plumber?
Call a plumber if a pipe has cracked or leaked, if you can’t find the frozen spot, or if water won’t come back after you’ve tried warming it. It’s also worth a call before winter if your home has pipes you know get cold every year. We can insulate them or move them to a warmer spot so you’re not dripping faucets every cold night.
What Happens When Meticulous Plumbing Comes Out?
We show up when we say we will, in uniform, and we put shoe covers on before we come inside. We’ll explain what we found and lay out your options before any work starts. When the job’s done, we clean up and recycle old pipe and parts.
While we’re there, we’re happy to do a whole-house plumbing inspection. It’s an easy way to find other pipes that might freeze, or small leaks, before they turn into bigger problems.
When to Drip Faucets FAQs
How long should I keep my faucets dripping?
Until the temperature is back above freezing and staying there, usually through the morning after the last cold night. Pipes take a while to warm up, so don’t shut the drip off the minute the sun comes out.
Does dripping faucets waste a lot of water?
Not much. A slow drip uses only a few gallons a night. That’s a small cost next to the water damage a burst pipe can cause.
Do I need to drip faucets if my pipes are insulated?
Insulation helps a lot, but it slows the cold down rather than stopping it. During a long or windy cold snap, it’s still smart to drip faucets on outside walls.
Do I need to drip faucets if I have PEX pipes?
PEX, the flexible plastic pipe in many newer and repiped homes, handles freezing better than copper because it can stretch a little. But it can still freeze and stop your water, and the fittings that connect it can still crack. Drip anyway.
Should I turn off my main water instead of dripping?
Only if you’re leaving home for a while. If you shut off the main, open your faucets to drain the lines. If you’re home and using water, dripping is the better choice.
Should I drip my faucets if I’m going out of town?
It’s better to shut off the main water and drain the lines, or have someone check on the house. Either way, leave the heat on at 55°F or higher.
Get Your Pipes Ready for Winter
Meticulous Plumbing is a family-owned Portland plumbing company. Schedule a visit online or call or text (503) 208-2812. Learn more about our leak repair and plumbing repair services, or check the areas we serve.
