how to fix frozen bathtub drain

You will need to have frozen bathtub drains if you live in cold regions, which can see freezing temperatures for several weeks each year. This is due to freezing weather, but also inefficient plumbing and leaks in walls that allow cold air into the trap pipe and freeze it.

If you have tried boiling water, but failed, and your beloved plunger has plunged away in vain, you now have water in the tub, and you’re left with no idea how to drain it. Here are my proven DIY methods to unfreeze a bathtub drain.


Remedy #1

The Wet/Dry Vacuum + Blow Dryer Method

If the wall (closet) is accessible at the drain end, you can cut the access panel at floor level. Then blow-dry the pipes to melt the frozen ones. For future assistance, cover the cut with insulation. Mount an access panel door in its place.

If this fails, you can continue on to the next step.

Use a dry/wet vacuum to extract the water and then use more hot water to unclog the tub’s drain. You could also try to drain the water by using a blow dryer with a high setting. Salt has been used for thawing. However, if your pipes are made of metal (especially the trap), it could be ingested and cause further problems. I wish you good luck, and please share your experience with bathtub drain thawing in the comments below.

Remedy #2

Baking Soda + Vinegar Method

Put a few tablespoons of baking soda into the tub drain and let it sit for 60 seconds. Pour 1 cup of distilled vinegar into the drain. Wait for the chemical reaction to occur for several minutes. You will hear a fizzing sound and bubbles as a result of the chemical reaction in the vessel. The mixture will not only clear the blockage, but it will also clean the pipe by removing any sludge. Step 2: Continue to the next step, even though the baking soda and vinegar mixture is already in your drain.

Combine salt and 3-4 cups boiling water. Slowly transfer the mixture into the tub’s drain. This will allow the vinegar and baking soda mixture to percolate inside the frozen pipe. Salt is an extremely strong element that speeds up the melting of ice.

Once the clog has been cleared, pour hot water down the drain. This will ensure that the drainage pipes have thawed properly.

Remedy #3

Space Heater Method

To warm the area, use a heat lamp or space heater. Pour hot water with safety salt down your drain. The heater will melt the frozen bathtub drain. To prevent a fire hazard, keep the heater 8 inches from the tubing and walls. Make sure that there are no flame-catching rugs and carpets directly in front of the heater.

Add Some Other Things To Get A Stronger Effect…

For a stronger thawing effect, you can combine any of these remedies with the below-listed techniques.

Heating the Pipe

Find the frozen section of the sewage line. Use your fingertips to locate the coldest section of the tubing. If you are unable to identify the origin, begin working on the tube closest to the tub drain.

Use a hairdryer. The tube should be heated from the lowest point. Wrap hot towels around the pipe if the area outside of the frozen pipe is damp. The piping should be thawed until water flows again.

Warning! Never heat the pipes with an open flame.

Heating the Vent Pipe

Heating the ventilation pipe (also known as a vent stack) is an option. Also known as a vent stack. This is the conduit which leads out of your house. This conduit is intended to supply fresh air for your plumbing equipment. It removes odorous air from your house.

The ventilation pipe must filter the fresh air into the drainage channel in order to drain the water. However, the vent tube must be able to filter fresh air into the drainage channel. If it freezes, the drain will not function.

If you’re handy and not afraid of heights, go into your attic to check if the exhaust pipes are frozen. To warm it up, you can use the hairdryer trick.

Increase Heat Levels

People reduce heat to save money. However, freezing pipes can come back to haunt them. Increase the heat to a higher temperature than what you have been using. This is not to say that the heat should be unbearably hot. It should only be a level of heating that is consistent and does not save money. Allow heat to reach unheated areas by opening your windows.

How to prevent future freezing of the BathTub Drain

The freezing of bathtub drains is a serious problem, especially if you live in cold areas.

To search for air leakage or uninsulated areas, open the area. Frosted pipes are often caused by the wind. Even a small opening in the wall will allow for enough cool air to freeze drainage pipes. I will remove all insulation to allow for a visual inspection. Infrared cameras are useful in these cases. The truth is fiberglass insulation does not block air infiltration. It must be kept from leaking.

I was contacted by a customer who had a similar problem. The bathtub drainage pipes were able to freeze because of air leakage through insulation and the soffit vent.

Proper vents ensure proper airflow from the roof vent to the ridge vent. They are usually made of Styrofoam, and can be found in many sizes and shapes. The insulation is then added to the roof. Proper vents allow fresh air to flow through the roof vent and soffit vent. The soffit vent allows air to flow into the proper vent in the attic. This helps to cool the attic throughout the summer and allows moisture to evaporate. Proper ventilation can also help extend the life of shingles and prevent ice jams.

Another problem I encounter is insulation that has been stuffed into spaces. Fiberglass insulation should be fluffy and loose. Compressed fiberglass can lose its R-value if it has a small amount of dead-air. Fiberglass insulation will not deteriorate if it is correctly installed.

To solve my problem, I attached Styrofoam vents at the soffit vent. I also reinstalled fiberglass insulation with high-density. Open-cell spray foam is another option, if you have the budget. You must secure the insulation batts. The edges are protected by the folds. These folds can be opened and stacked onto the wooden board.

It is important to test and insulate the floor rim joint and the exterior wall of the floorjoist. The electrical connection, dryer vents and piping must be checked for air leaks. Foam insulation or caulk can be used to keep hot air in and cold air out.

To seal air gaps and increase the R-value, I filled all these areas with 1.5-inch Styrofoam rigid board insulation. To seal any board gaps, I used foil HVAC tape and filled in the wide spaces with expanding foam. This will not only heat your unheated wall, but it also stops the flooding of air that can freeze your bathtub drain pipes and traps.


A drainpipe that has been properly conditioned will drain dry and won’t freeze when in use. It is not uncommon for drainpipes to freeze at sub-zero temperatures. Because it retains water, a blocked drain can freeze. If the drain is not properly pitched, it will freeze water. Dripping faucets can cause water to cool and freeze several metres down the drain line. This is why I shudder every time I hear someone recommend that a faucet be left dripping to prevent pipes from freezing. In my 10 years working in plumbing, I’ve seen many cases where the primary sewer pipe was frozen due to a leaky toilet or faucet.

If neither of these freezing conditions have occurred, the only place your drainage line may be frozen is under the tub drain. This trap is a tube-shaped drainage tube that contains water. It prevents sewage gasses entering your house. The frozen bathtub drain can be unclogged by heating it. This trap can be accessed either through the wall at the back of your tub drain or through the roof. The hairdryer should be directed to the area where the trap is. Once the ice has melted, the hairdryer will control the flow. You can also check for any pipe cracks by following the instructions I gave earlier. However, in most cases, this should work.

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