How To Stop Toilet Tank Sweating

12 May 2017
 Categories: , Blog


If your toilet tank sweats, you should fix it right away to avoid floor damage and fixture corrosion. Condensation is caused by the outside temperature mixing with the temperature inside the toilet tank. Think of what happens to a cold drink on a hot day. You can easily fix toilet tank sweating by following these tips.

Prepare to Work

For this project, you need:

  • work gloves
  • tape measure
  • sponge
  • large towel
  • fan dehumidifier
  • tank cover or fabric insulating kit
  • pipe cutter (optional)
  • tempering valve (optional) 
  • solder kit (optional)

Shut off the water to the toilet, which is commonly a valve near the wall behind or beside the toilet. Flush the toilet to drain the tank. Carefully remove the tank lid, and set it on a safe spot. Dab extra water in the tank with a sponge, and dry the inside with a towel.

Keep the Tank Insulated

Buy a tank cover to wrap around the toilet tank and lid. Terry cloth material is commonly used for tank wraps. If you are crafty, knit or crochet a toilet tank lid and tank cover. Glue a toilet tank liner on the inside of the tank lid.

You may also install a toilet tank foam insulation kit. Measure the tank walls, and cut foam insulation to fit. Glue the foam pieces around the tank, and let the adhesive dry.

Increase Ventilation

Poor ventilation is another cause of toilet tank sweating. Ventilation will decrease the temperature of the air around the toilet.

Turn down the heat when possible, and open a window, especially after showering. Run the exhaust fan, the air conditioner, or aim a fan directly at the toilet.  

The air dries faster when the toilet has enough space between the wall and toilet. If it lacks space, set up a dehumidifier.

Install a Tempering Valve

A tempering valve attaches to the cold water line, so a hot water line can be added. It reduces condensation by raising the temperature of the water entering the tank, which reduces the temperature difference between the outside air and the tank.

Talk with a plumber like Moon Valley Plumbing for more information. Have a plumber install the valve, or install it yourself if you have experience with solder. Follow the toilet water supply line to a hot water pipe nearby, and shut off the water to the pipe. 

Use the hacksaw to cut the toilet supply pipe, and attach this end to the cold water inlet valve on the toilet. Find a convenient location on the hot water pipe, and solder a tee fitting on it

Run copper piping from the tee to the hot water inlet on the valve. Dry fit the pipe fittings, then solder them. Attach the pipe to the hot water inlet. Restore water, and adjust the temperature on the tempering valve with a screwdriver.