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Fixtures & Renovations

6 ways to stop your toilet from sweating

Quick answer

A sweating toilet is condensation: warm, humid air hits the cold tank and water beads up. To stop it, lower the humidity (run the exhaust fan or a dehumidifier), insulate the tank with a liner, or have a plumber install an anti-sweat (mixing) valve that warms the water filling the tank.

A Powell's plumber working on a toilet

Toilet tank condensation, commonly referred to as toilet sweating, is a pesky problem that can cause water damage, create an environment prone to mold and mildew, and generally make your bathroom a less pleasant place. This issue occurs when the humid air in the bathroom comes into contact with the cold surface of the toilet tank, causing water to condense and drip down. In this blog, we’ll discuss six ways to stop your toilet from sweating and prevent toilet tank condensation.

Understanding the Cause

Toilet tank condensation typically happens in the summer when warm, humid air meets the cold surface of the toilet tank. This is similar to how a cold drink sweats on a hot day. The difference in temperature causes moisture in the air to condense on the cooler surface.

Solutions to Prevent Toilet Tank Condensation

  1. Install a Toilet Tank Liner: A toilet tank liner is an insulating material that you place inside the toilet tank. This liner helps to keep the tank’s exterior surface from getting cold enough to cause condensation. It’s an affordable and straightforward solution that can be found at most home improvement stores.
  2. Use Anti-Condensation Paint: Applying anti-condensation paint to the exterior of the toilet tank can also help. This special paint contains insulating properties that help prevent the surface from becoming cold enough to attract condensation.
  3. Install a Mixing Valve: A mixing valve blends a small amount of hot water with the cold water entering the toilet tank, raising the temperature of the water slightly. This can significantly reduce condensation. Installing a mixing valve may require professional assistance, but it’s a long-term solution that effectively addresses the root cause of toilet sweating.
  4. Reduce Bathroom Humidity: Lowering the humidity level in your bathroom can also help prevent condensation. Here are some ways to achieve this:
  • Ventilation: Ensure your bathroom is well-ventilated. Use an exhaust fan during and after showers to expel humid air.
  • Dehumidifier: A dehumidifier can be a great investment, especially if you live in a particularly humid area. It will help maintain a lower humidity level in the bathroom.
  • Open Windows: When weather permits, open windows to allow fresh air to circulate and reduce humidity.
  1. Use a Toilet Tank Cover: A fabric toilet tank cover can absorb condensation, preventing it from dripping onto the floor. While this doesn’t stop the condensation itself, it can manage the water more effectively, preventing damage to your bathroom floor.
  2. Upgrade to a Low-Flow Toilet: Low-flow toilets use less water per flush, meaning the water in the tank is less likely to be cold enough to cause condensation. This upgrade not only helps with condensation issues but also conserves water, making it an environmentally friendly option.

Maintenance Tips

Even after implementing these solutions, ongoing maintenance is crucial to keep your bathroom free of excess moisture and mold.

A Powell's plumber working on a toilet
  • Regular Cleaning: Wipe down your toilet tank regularly to prevent mold and mildew buildup.
  • Check for Leaks: Ensure there are no leaks in your toilet, as leaks can contribute to humidity and condensation issues.
  • Monitor Humidity Levels: Keep an eye on the humidity levels in your bathroom using a hygrometer. Ideally, the humidity level should be below 60% to prevent condensation.

Got a Sweating Toilet?

Toilet tank condensation is a common issue that can lead to more significant problems if not addressed. By understanding the causes and implementing the solutions outlined above, you can keep your bathroom dry, reduce the risk of mold and mildew, and maintain a more pleasant environment. Whether you opt for a toilet tank liner, anti-condensation paint, a mixing valve, or humidity control measures, taking action will help you stop your toilet from sweating and prevent the associated issues. Remember, the key is to reduce the temperature difference between the water in the tank and the surrounding air, and to control the humidity in your bathroom.

More tips from our team

  • Fix a running toilet. A leaky flapper keeps refilling the tank with cold water, which keeps it sweating. Replace the flapper and the sweating often eases.
  • Run the exhaust fan. Leave it on for 20 minutes after a shower to pull the humid air out.
  • Summer is worst. Expect more condensation on hot, humid days, especially if your home isn't air-conditioned.

Frequently asked questions

Why is my toilet tank sweating? +

Cold water in the tank makes the outside of the tank colder than the air. When warm, humid air touches it, the moisture condenses into droplets. It's worst in summer.

Is a sweating toilet a leak? +

No, but it can look like one. Dry the tank and floor, then put a few drops of food coloring in the tank. If color shows up in the bowl or on the floor, you have a leak too.

How do I stop condensation on my toilet tank? +

Run the bathroom fan during and after showers, use a dehumidifier, add a foam tank liner, or install an anti-sweat valve. A running toilet makes sweating worse, so fix the flapper too.

Can a sweating toilet damage my floor? +

Yes. Constant drips can rot the subfloor, loosen tile and grow mold around the base. Put a towel or drip tray down until it's fixed.

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