• In this video, This Old House plumbing and heating contractor Richard Trethewey explains how to fix a sweating toilet tank.


    1. Turn off water and drain the pipes.
    2. Cut a tee-fitting into a nearby hot-water water pipe.
    3. Dry-assemble the various copper pipes and fittings to the anti-sweat valve.
    4. Solder together the assembly, making sure the valve is positioned vertically.
    5. Install the soldered valve assembly so that it connects the hot-water pipe with the cold-water line leading to the toilet.
    6. Solder the valve assembly to the existing pipes.
    7 .Turn the water on and check for leaks.
    8. Adjust the valve to allow just enough hot water into the toilet to raise the temperature of the water in the tank.
    • Difficulty: Moderate
      You’ll need basic plumbing skills, including knowing how to solder copper pipe

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      Tools List

      • propane torch
        Propane torch, used to solder together pipe and fittings
      • tubing cutter
        Tubing cutter, used to cut copper pipe
      • adjustable wrench
        Adjustable wrench, used to install threaded fittings

      Shopping List

      1. Anti-sweat valve
      device that introduces some hot water to toilet’s cold-water supply line

      2. Copper pipe and assorted fittings

      3. Lead-free solder

      4. Flux

      5. Emery cloth

      6. Teflon tape

      7. Clean rag