how to fix frozen bathtub drain

Frozen bathtub drains are a must if you live somewhere cold where there is freezing weather for weeks. This is due to the fact that cold air can enter the trap pipe, freezing it.

If the boiling water kettle failed to please you, then your beloved plunger plunged away in vain. You still have water in the bathtub and are utterly lost on how to drain it. I’ve listed my tried-and-true DIY methods to flush out the drain and melt the ice block.

Treatment # 1

The Wet/Dry Dry Vac + Blow Dryer Method

If you have a wall or closet that opens at the drain side of the tub, you may be able to break or cut the access panel. Once the pipes are thawed, blow-dry it. Cover it with insulation to protect the pipes in the future. Install an access panel door on the spot where the cut was made.

If that fails continue to the next step.

You can use a vacuum to remove the water. Then, heat more water until the tub’s drain freezes. You can also use the hot setting of the blow dryer to heat the water. I have seen salt used to thaw, but if you have metal pipes (especially traps), you run the risk of it getting ingested and causing more problems. Let me know what you think about this bathtub drain thawing solution in the comments section below.

Treatment # 2

Baking Soda + Vinegar Method

Place a handful of baking powder into the tub drain. Wait for 60 seconds. The chemical reaction will take place when you pour 1 cup of distilled water into the drain. The chemical reaction that takes place inside the vessel will cause bubbles and a fizzing sound. This mixture will clear the blocked frozen blockage and also clean out the pipe of sludge. You can continue with step 2 even though the baking soda/vinegar mixture is already in drain.

Add 3-4 cups of boiling hot water to the salt mixture. Slowly transfer this mixture to the tub’s drain. This will allow the mixture of baking soda and vinegar to percolate within the frozen piping. Salt is a powerful element that accelerates ice melting.

To ensure drainage pipes are properly thawed, flush plenty of hot water down your drain once the clog is cleared.

Treatment # 3

Space Heater Method

You can heat the area with a heat lamp, space heater or heat lamp. Then pour hot water and safety salt down the drain. It will melt the bathtub drain. To avoid a fire hazard, the heater should be held 8 inches from the tubing or walls. Also, make sure you don’t have any flame-catching rugs or carpets near the heater.

Combining Additional Items For A More Powerful Impact…

Combining any of the above-mentioned remedies with these techniques will result in a stronger thawing.

Heating of the Pipe

Locate the frozen portion of the sewage pipe. Find the coldest portion of the tubing using your fingertips. If you can’t find the source, search for the tube closest the tub drain.

Use a hair dryer. Heat the tube starting from the coldest part. Wrap hot towels over any damp areas of the frozen pipe. Allow the pipe to cool down until it is able to flow again.

Warning: Do not attempt to heat pipes with an open flame.

Heating of the Vent Pipe

You might even consider heating your ventilation pipe (also called vent stack). Vent stack is also known. This is the conduit that leads outside of the house. It provides fresh air for your plumbing equipment. It eliminates odorous odours from your home.

The ventilation pipe must filter water into the drainage channel to drain it. The drain will become blocked if the vent tube freezes.

If you have the skills and are not afraid of heights, you can go into your attic. It can be heated up using the hairdryer technique.

Increase Heat Levels

People often lower the heat in order to save money. This can lead to freezing pipes. You can turn the heat up to a higher level than what you are used to. I’m not talking about heating the house to an inexplicable level, but a steady heat that does not cost money. Let the heat reach places that are not heated by opening up.

Prevention of future freeze-ups in BathTub Drains: Here’s what I did and so should you (A guide exclusively for plumbers)

If your bathtub drain freezes, it is a problem.

You can search the area for leakage or places that are not insulated. Wind is a major contributor to the formation of frozen pipes. A slight opening can allow cool air to reach the drain pipes. I will take out all of the insulation in order to make a clear visual inspection. For such cases, an infrared camera can be helpful. Fiberglass insulation is not designed to block air infiltration. Therefore, it must be sealed.

I met a customer with a similar problem. Air got through insulation and into the insulated wall through the soffit vent, causing the bathtub drainage pipes in the wall to freeze.

Vents that are properly designed and installed ensure adequate airflow between the ridge vent and the eaves. They are typically made from Styrofoam and available in many shapes and sizes. They are then covered with insulation. Proper vents can be built to allow fresh air flow upwards through the roof vent and the soffit ventilation. Air can flow through the soffit vent to the appropriate vent in your attic. This allows the attic to remain cool in the summer, and it encourages moisture to evaporate. Good ventilation is important to prolong the life of your shingles and to avoid getting stuck in ice.

Insulation that is too tight in spaces is another problem I often encounter. Fiberglass insulation must be soft and flexible. The R-value of compressed fiberglass insulation will decrease if its dead-air area is small. Fiberglass insulation is durable if installed correctly.

To resolve my issue, I attached Styrofoam vents on the soffit vent. I then reinstalled fiberglass high density insulation. If you are able to afford it, open-cell spray foam may be a better choice. The insulation batts must be secured. These are why the edges of the insulation batts should be covered with folds. These folds can be opened up and stacked onto the wooden board.

The floor rimjoist and the section of the exterior wall should be tested and insulated. Also, the electrical connections, dryer vents, piping, and electrical connections should all be checked for any air leaks. Caulk or foam insulation should be used in order to keep the hot and cold air out.

I then filled all the areas with 1.5-inch Styrofoam rigidboard insulation to close air gaps and maximize R-value. I used foil HVAC tape to seal board gaps and some large holes with expanding foam. This not only warms unheated walls but also stops air from flooding your pipes and traps, which can cause them to freeze.


A properly-conditioned drainpipe will usually drain dry and not freeze during use. A drainpipe can freeze in temperatures below zero. A blocked drain will freeze because it holds water. A poorly pitched drain will trap water and freeze it. A dripping faucet can cause water cooling and freezing several meters below the drain line. This is the reason I cringe whenever I hear that people recommend keeping the faucet dripping to keep the pipes from freezing. In my 10 years of experience in plumbing, I have seen several instances where the primary sewage line was frozen by a leaking faucet or a toilet.

If none of the above conditions has occurred, the only area where your drainage line might be frozen is the trap beneath the tub drain. The trap is a rectangular drainage tube with water inside. This prevents sewage gases from getting into your home. It can be heated to unclog the blocked bathtub drain. You can either enter the trap through the wall or the roof. Follow the hairdryer’s flow to the trap, and the ice will melt. If you are unable to get the ice to melt, check for leaks in your pipes and follow the steps I have described.

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