Does Your Toilet Sweat? How to Fix the Plumbing Problem

Shannon Lee

A significant part of taking care of your old house includes maintaining the plumbing. With all the old pipes, ancient fixtures, and the occasional "what were they thinking?" configurations found in old houses, plumbing problems are one of those things old house owners just have to get used to.

Many plumbing problems fall in the realm of the professional plumber. But some of those problems, like the "sweaty toilet" phenomenon, can be fixed with a little bit of do-it-yourself know-how.

Toilet Condensation: A Common Plumbing Problem

During very humid months, toilet condensation can become a serious issue. Here's what you need to know to stop the problem in its tracks:

  • Condensation on your toilet happens during the most humid weather. The water in the toilet bowl is usually below room temperature, or about 50-60 degrees Fahrenheit. The much warmer air around the toilet can lead to condensation on the exterior. Over time, the water can seep underneath your toilet and cause water damage.
  • The first remedy is the most simple one--use a dehumidifier or air conditioner in the bathroom to dry out the area and keep the condensation from forming. Dehumidifiers are often inexpensive and can work very well in small areas.
  • You could try a toilet tank insulator, but keep in mind that these might not work as well as other methods. However, they are often inexpensive, so it might be worth a shot before you move on to the next option.
  • Anti-sweat valves that install on your water line can allow a bit of hot water into the toilet bowl with every flush, thus raising the water temperature and eliminating the condensation problem. Some anti-sweat valves are easier to install than others, depending on where you choose to place the valve. Choices depend on the configuration of your pipes and how easy it is to reach the water lines.
  • Before you begin any plumbing project, shut off the water, gather the appropriate tools, and read the instructions that come with your new parts. Many projects that seem difficult are actually quite simple if you take the time to understand how it all fits and works together.


You can install many anti-sweat valves on your own in less than an hour. However, more elaborate plumbing setups can require work that the average homeowner might not be comfortable with doing on their own. In that case, call in a professional contractor and watch the work on your old house unfold, learning as you go.

About the Author

Shannon Dauphin is a freelance writer based near Nashville, Tennessee. Her house was built in 1901, so home repair and renovation have become her hobbies.

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