Can Pipes Burst If the Water Is Shut Off?

Short answerYes, if water is still in them. We expect closing a valve stops new water, but what's left can still freeze and expand. Utah State says that ice can crack or split a pipe. University of Illinois says to drain and shut off the system when you're away, and to keep the heat at 55 degrees or more.

What this costs

Our national estimates, not quotes.
Option	Job	Low	High
Repair	Pipe Repair	$130	$800

Shutting off helps, but in a different way

We expect a closed main means a split pipe leaks only what's left in the line, rather than running for days. Utah State says being able to shut off the water in a leak can greatly reduce damage. We don't expect it to stop a full pipe from freezing. That's why University of Illinois pairs the words drain and shut off.

If you're leaving a house in winter

We expect that draining a whole house has traps, such as the water heater and toilets. We recommend asking a plumber to do it or show you, including how to handle the heat source for any boiler or water heater.

Keep the heat on. University of Illinois and NC State Extension both say no lower than 55 degrees.
Have someone check daily that the heat is on, as University of Illinois suggests, or drain and shut off the water system, except indoor sprinkler systems.
Shut off and drain pipes leading outside, and disconnect garden hoses, according to NC State and University of Georgia Extension.

If a pipe already froze

Know where the main shutoff is. Utah State says the thawing line can leak, and that a plumber may be your best contact. If you do it yourself, it says to shut off the main first, then open the faucet on the frozen line. University of Illinois says never to thaw with an open flame or torch and to watch for electric shock around standing water.

Frozen Pipes? How to Thaw Them Safely

Common questions

Should I turn off my water when I go on vacation?

In freezing weather, University of Illinois says to drain and shut off the water system or have someone check on the house daily. Utah State says shutting off the water can greatly reduce leak damage. Keep the heat on, and we recommend asking your insurer what they require.

Do outdoor faucets need draining?

Yes. University of Georgia Extension says to shut off water at the outdoor faucet and drain the pipe. NC State Extension also says to disconnect hoses.