Symptoms
- Toilet won't flush or fill in very cold weather
- Frost visible on the tank or supply line
- Water in the bowl is not moving or has a thin layer of ice
- Located in an unheated or poorly insulated space
Likely causes
- CommonLoss of heat to the bathroom or buildingA furnace failure, power outage, or vacant unheated property lets pipes and fixtures get cold enough to freeze.
- CommonUninsulated exterior wall plumbingToilets on an exterior wall with poor insulation are more exposed to freezing temperatures.
- PossibleSupply line frozen before reaching the tankIce can form in the line before it even reaches the toilet, cutting off water before the tank freezes.
What to do
- If you suspect freezing, do not attempt to flush, since pressure against ice can crack the tank or bowl.
- Raise the room temperature as much as possible, using a space heater at a safe distance if the main heat source has failed.
- Gently apply warmth near the supply line and shutoff valve, such as a hair dryer on low, moving constantly and never using an open flame.
- Once thawed, check carefully for cracks in the tank, bowl, and supply line before using the toilet again.
- For a property that will be unheated for a while (vacation home, vacant unit), shut off the water supply and drain the tank and bowl, adding RV antifreeze to the bowl and tank to prevent freezing.
- Improve insulation around exterior wall plumbing for the future if this is a recurring problem.
Tools and parts
- Space heater
- Hair dryer
- RV/marine antifreeze (for winterizing)
When to call a pro
Call a plumber if you can't safely thaw the line yourself, if a pipe has already burst, or to properly winterize a property that will sit unheated.
Safety
Use caution
Never use an open flame to thaw pipes or a toilet, and don't flush a toilet you suspect is frozen, since pressure can crack the porcelain.