When warm and humid weather arrives, toilet tanks can start to sweat. When the tank fills with cold water, the outside of the tank drops in temperature. The warm air comes in contact with the cold tank, and condensation forms on the outside.

Why It’s a Problem

It’s more than a mild inconvenience when condensation starts to form on the outside of your toilet tank - it can cause serious damage from dripping onto your bathroom floor. It can leave the floor damp for days, damaging the floor and tiles, and, in older toilets, can even damage the bolts that hold the toilet to the floor. Fortunately, there are some quick and affordable ways to stop the condensation.

How to Fix It

Insulate the Tank 

One of the easiest way and most affordable ways to fix a sweaty toilet tank is as simple as adding insulation, preventing the outside of the tank getting cold. The Anti-Condensation Liner is a closed cell foam with an adhesive backing. Installing it as simple as emptying and drying your toilet tank, cutting it down to the height of the tank with scissors, peeling the protective sheet off to expose the adhesive backing, and applying to the inside of the tank. Grab a liner here or from Walmart or Amazon.

Check the Flapper

If your flapper is leaking, cold water is constantly being added to the tank. It wastes water, but also makes the tank colder and more likely to sweat. Check if your flapper is creating secure seal by putting a few drops of food coloring in the tank and waiting. If after an hour, the color appears in the bowl of the toilet, you may have to replace your flapper.

Install an Anti-Sweat Valve

Installing an anti-sweat valve works by adding hot water to the water entering your toilet. You’ll need a plumber to install the valve as it can be complicated and involves shutting off the water to the house, and cutting and soldering pipes. After the valve is installed, cold and hot water will mix before reaching your tank raising the temperature of the water and preventing condensation.

While there are other options out there, they can be expensive or tedious, such as installing a new insulated toilet or constantly cleaning and emptying a drip tray. For the low cost of a toilet kit liner, your toilet can be set up to stop sweating in time for summer with no extra upkeep.