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How to Install a Water Saving Toilet

Ask This Old House plumbing and heating expert Richard Trethewey replaces an old toilet with a "Water Sense" solution.


  1. Shut the water off at the toilet. The shut off valve should be to the left of the toilet.
  2. Flush the toilet to drain out as much water as possible. The rest can be removed with a sponge and a bucket.
  3. Break the water connection from the hose to the toilet tank. It usually can be loosened with hands alone.
  4. Use the open ended adjustable wrench to loosen the closet bolts on both sides of the toilet. Remove the nut and the washer.
  5. Use the grips under the toilet to carefully lift the toilet straight up off the bolts.
  6. Wearing gloves, remove the wax around the flange using a putty knife.
  7. Check to ensure the closet flange is intact. Replace if it is broken.
  8. Assemble the new toilet using brass tank bolts and the tank to bowl gasket, both of which should be included with the toilet.
  9. Attach the new toilet seat to the bowl.
  10. Insert new closet bolts into the flange.
  11. Add a new wax ring to the flange.
  12. Carefully put the new toilet back on the flange and push to set into the wax ring.
  13. Add the toilet cap base to the closet bolts on both sides.
  14. Put the washer and nut back on the closet bolts. Secure them on both sides with the open-ended adjustable wrench. Take turns securing each side and do not overtighten to prevent damaging the toilet.
  15. Use the mini hacksaw to carefully cut the closet bolts close to the nut.
  16. Add the toilet cap to the closet bolt. It should snap right into the cap base.
  17. Hand tighten the water connection back to the toilet.
  18. Turn the water back on.
  19. Use caulking around the bottom of the toilet.


Richard installed the Wellworth Dual-Flush toilet, manufactured by Kohler.

Expert assistance with this project was provided by the San Francisco Public Utilities Commission and by George Salet Plumbing.