Cold weather can affect your house's plumbing in various ways, especially once the outside temperature dips below freezing. Knowing the potential dangers to your plumbing from the cold weather helps you take steps to keep your plumbing functioning properly in cold weather, as well as clear up any problems you may encounter.

Vent Pipe Clogs

Cold weather may bring problems with the plumbing vent pipes in your house, especially if two or more drains in your house clog at the same time. The plumbing vent pipes connect to multiple plumbing fixtures, venting not only sewer gases from the drainpipes but also allowing fresh air to flow into the pipes. If ice collects inside the vent pipes to the point where the ice clogs the pipes, the drains connected to the blocked pipes may behave as if they are clogged.

Drainpipe Clogs

Your house's drainpipes may clog at any time of the year when debris such as soap scum and hair collects on the walls of the pipes, eventually cutting off any passage for water to drain. Oil and grease that you used to cook may also create clogs in the drainpipes and should not be washed down your sink drain. In cold weather, the grease or oil stiffens more in the pipes, making it more likely that there will be clogs in the pipes. If you suspect the drainpipes have frozen, pouring hot or even boiling water down the drain should eliminate the ice blockage.

Thawing Pipes

You may thaw out either drainpipes or plumbing vent pipes, restoring your plumbing to its regularly operating condition. Applying a direct flame to a frozen pipe using a blowtorch or similar device can cause the pipe to split from the extreme temperature increase. Instead, heat the pipe with a hair dryer or wrap towels that have been soaked in hot water around the frozen pipe. If the vent pipes are frozen, you can also pour hot water down the pipe openings to break up the ice clog.


Once you have had problems with the cold weather leading to clogged pipes, you need to take steps to ensure the pipes do not freeze again. Increasing the temperature in the part of the house where the pipes have frozen helps prevent future problems. Insulate unfinished basements or attic spaces to keep pipes from freezing, or slide insulation sleeves over the pipes. If grease or oil has caused a clog, pour any grease or oil you have cooked with into a container and dispose of it that way rather than washing it down the drain.