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I have a toilet which has water condensing on the outside of the tank and then dripping down onto the floor. No, the tank is definitely not leaking.

This is weather related, as this always happens on somewhat warmer days (i.e. > 70 F) and when we have no HVAC running (i.e. < 90 F), so our windows are open and there is some humidity in the air.

Obviously the cold water in the tank is causing the condensation to occur on the outside.

Can anyone recommend a solution to this problem, other than placing buckets behind the toilet? How do I keep my floor from getting wet every spring and fall?

marked as duplicate by isherwood, Daniel Griscom, ThreePhaseEel, Community Jun 9 at 14:10

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A cheap solution is to increase airflow around the toilet. Place a small fan where it's directed toward the tank. By increasing the rate of evaporation less dew will form.

There are insulated tanks available which have foam linings. You may be able to find one compatible with your stool.

The converse of a tank insulated on the interior would be to wrap the tank with something that would insulate, such as a fabric. You could fit a towel or cloth around the tank and fasten it at the rear.

Otherwise, if your plumbing is accessible, you could tee a hot water line into your cold water toilet supply and, by way of a valve, deliver a small amount of hot water to the toilet, raising the temperature. You'd just have to get it above the dew point, which is rarely over 75F.

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