• In this how-to video, This Old House plumbing and heating expert Richard Trethewey shows how to install a new water-saving toilet.

    1 Remove the old toilet and both closet bolts; use a putty knife to scrape the old wax seal from the closet flange (toilet drain pipe).
    2 Inset the two new closet bolts into the slots in the closet flange.
    3 Place the plastic mounting flange over the closet flange.
    4 Lay the paper template that comes with the toilet over the mounting flange and mark the screw-hole locations for both mounting blocks.
    5 Drill through a tile floor using a carbide-tipped masonry drill bit.
    6 Switch to a twist-drill bit and bore screw-pilot holes into the wood subfloor.
    7 Screw the two mounting blocks to the floor.
    8 Press a wax seal onto the plastic mounting flange, then set it on top of the closet flange; add washers, hex nuts, and then tighten with an open-end wrench.
    9 Set the new toilet into place, making sure it fits over both mounting blocks.
    10 Screw through the toilet base and into the mounting blocks to secure the toilet; conceal the screw heads with the chrome caps provided.
    11 Remove the flush valve from inside the toilet tank.
    12 Connect the flexible water-supply line to the underside of the tank.
    13 Carefully set the tank onto the bowl and tighten the two bolts.
    14 Install the flush valve inside the tank and connect the refill tube.
    15 Connect the water-supply line to the shut-off valve, then open the valve to fill the toilet tank.
    16 Flush the tank a few times and check for leaks.
    See products and services from this episode.
    • Difficulty: Easy
      Requires carefully following installation instructions, but even first-time plumbers should be able to complete this project.

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      Tools List

      • putty knife
        Putty knife, used to scrape the old wax seal from the closet flange
      • drill
        Cordless drill, used to drive screws and drill screw holes
      • adjustable wrench
        Open-end wrench, for tightening hex nuts

      Shopping List

      1. Dual-flush toilet, water-saving model to replace old toilet

      2. Wax toilet seal, used to seal the toilet to the closet flange