How To Insulate A Toilet Tank

Toilet tanks often attract condensation from the moist warm air of our bathrooms. To stop this, you are wondering how to insulate a toilet tank. In this post, we gather up-to-date information to answer your question thoroughly.

There are a few ways to insulate your toilet tank. However, they all involve adding a layer of protection between the warm outside air and the cold tank water. The best methods include the following:

  • Install A Toilet Tank Liner
  • Line Your Toilet with Bubble Wrap
  • Cover Your Toilet Tank with A Decorative Cover

Keep reading the rest of this post for details on accomplishing each of the above toilet tank insulation techniques. We also provide additional tips on how to stop toilet tank condensation and answer questions related to the topic of this post.

An overhead view of a brand new insulated toilet tank, How To Insulate A Toilet Tank

Ways to Insulate A Toilet Tank

The recommendation outlined in the following subsections are all visually attractive and may even brighten up your bathroom decor. Even when the insulation is inside the tank, the reduction in condensation improves your bathroom appearance and reduces the amount of needed cleaning.

Install A Toilet Tank Liner

The easiest way to insulate your toilet tank is with a specialized toilet tank liner. These products are essentially thin foam insulation attached to your tank walls with a sticky backing. To make the installation of these liners easier, follow our step-by-step directions.

Click here for a toilet tank liner kit from Amazon.

1. Shut off Water

Residential toilet water shutoff valve

First, shut the water off to your toilet. Usually, there is a simple twist valve near the ground behind your toilet.

2. Empty Tank

Now, empty the tank of water. Fortunately, all you need to do is flush! It might take several flushes until the tank empties. Take note that some residual water will sit in the tank's bottom.

Take the tank lid off during the emptying process so you can be sure that all the water is successfully draining. If you notice water refilling into the tank, you did not entirely shut off the supply line, or there is an issue with your supply line shut-off valve.

White toilet tank with an open lid and flush system

3. Clean Inside of Tank

Unfortunately, it is now time to clean the inside of your tank. This process is more daunting than it sounds but is made much easier with good rubber gloves and a long-handled brush.

Click here for rubber gloves from Amazon.

First, spray the inside of the tank with any type of hard surface cleaner. Then, scrub the walls and mechanisms clean. Occasionally, you might want to rinse the walls with water which you can then flush away as you did the original tank water.

4. Fully Dry out Tank

Once the tank is clean, it is time to dry the inside the tank. First, use a towel and a sponge to sop up all of the standing water and wet spots that you can. Take the sponge, let it soak up the standing water, and then squeeze it out over another drain. Repeat this process until you cannot soak up any more water.

Click here for a clamp light from Amazon.

Take a lamp or utility light and point it into the tank. This will increase the tank's temperature and help all of the remaining water evaporate away. Experts recommend that you wait about 12 hours to allow the tank to dry thoroughly. However, you may find that your tank dries out much more quickly.

5. Install Bottom, Sides, Front, and Back

Now, it is time to install the actual tank liner. As pictured above, these liners come on a roll and have one side that is very sticky once you remove the backing. Thus, be sure to have each piece entirely cut before removing the backing.


Installing the bottom piece is the most complicated because of the difficult-to-reach position and the several apparatuses in the way.

First, measure and cut out a piece of liner that fills the entire space. Then, cut out circles that fit around the pipes and other toilet parts that stick up from the bottom. Use scissors to cut the liner.

To slip the circle holes into place, you will need to cut a slit from the circle to the edge. Be sure that all slits point to the same edge.

Now, remove the backing and slide the bottom insulation into place. Work carefully, and plan which side will be easiest to approach from. Once it is in place, firmly press the adhesive into your toilet tank bottom.

Sides, Front, and Back

The sides, front, and back can often be insulated with a single piece of foam. To prepare your foam, first, cut it down to height at the total circumference of the inside of the toilet tank. Remember, you only need to insulate to above the depth of the water.

Now, you will need to notch around any obstructions in the walls. Usually, only the bar connects the plunger to the flushing handle. For this, you can cut a small U-shape in the foam insulation.

After removing the backing, you can slide the large piece of insulation in so it covers all four sides. Press this down, so it makes good contact at all points.

Sometimes, installing the sides in multiple individual pieces may be easier. This makes the application easier and spacing any notches much simpler.

Fill In Gaps

If there are any significant gaps on corners or edges, you can fill those in with any extra insulation. While working around any moving parts, be sure not to stick those parts to the toilet bowl. This could hinder your ability to flush the toilet.

6. Let Adhesive Dry

While the insulation kit directions do not recommend this step, it is wise to allow several hours for the adhesive to fully cure onto the tank walls. After this time, turn the water back on and use your toilet as normal.

Line Your Toilet with Bubble Wrap

Man holding bubble wrap

Bubble wrap is an alternative to specialized toilet tank insulation sheets. This material is, after all, both insulative and waterproof.

Follow the general directions outlined for the insulation kits above to install bubble wrap. This involves cleaning your tank, letting it dry, and cutting pieces that fit the bottom and all four sides of your toilet tank.

Click here for silicone caulk from Amazon.

However, to attach the bubble wrap to your toilet tank, you must use waterproof silicone caulk. Since this is a relatively small job, purchasing the caulk that comes in a hand squeezable job will likely provide more than enough glue.

Take note, be sure to not over caulk around any moving toilet parts as this could hinder toilet mechanisms and make flushing more difficult or impossible.

Cover Your Toilet Tank with A Decorative Cover

Decorative covers are generally just attractively patterned cloth designed to fit around your toilet tank snuggly. These only work if they cover the entire tank.

Click here for a bath set that includes a toilet tank cover from Amazon.

For less severe condensation issues, the minor insulation provided by these covers is sufficient. However, if you have serious condensation on your toilet tank, these covers may not be enough.

Why is my toilet sweating?

Your toilet is sweating because warm air can hold more moisture than cold air. Specifically, the cooler water in your toilet tank also makes the ceramic toilet tank cooler. Then, when the warm moist air of your bathroom hits the tank, it cools, and some of the water falls out onto your tank.

How do I stop my toilet tank from sweating?

In addition to adding insulation, you can stop your toilet tank from sweating by lowering the moisture content of your air, by adding a toilet mixing valve, and by getting rid of your tank.

Lower Bathroom Moisture

If there is less moisture in your bathroom, you can expect less toilet condensation. Accomplish this by running your air conditioner, routinely running your bath fan, using a dehumidifier, taking shorter showers, and cleaning up any residual water as soon as it spills.

Add Toilet Mixing Valve

Toilet mixing valves inject warm water into your toilet tank from your home's water heater. By warming the water in your tank to the air temperature, the process of condensation cannot occur. Usually, this is a job for a plumber.

Go Tankless

Tankless toilets flush from water stored in your home's plumbing instead of a tank. You do not have to worry about toilet tank sweating by removing the tank.

Are most toilet tanks insulated?

No, most toilet tanks are uninsulated. This is because, in most situations, the difference in temperature between your toilet water and the air is not great enough to lead to significant condensation. Further, the thick ceramic walls stop a large portion of the temperature transfer.

Do I need an insulated toilet tank?

Overhead view of a brand new insulated toilet tank during new house construction

You only need an insulated toilet tank if you have condensation issues. According to the EPA, excess moisture can lead to mold and mildew growth and damage your home's structure. These issues can be both unhealthy and costly.

Additional Reading

To learn more about proper temperature and moisture control in your bathroom, read these excellent HVAC Seer articles:

In Closing

This post describes step-by-step how to insulate a toilet tank, including three different ways to accomplish this task. To close, we answer several questions related to the topic of this post. Good luck!

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