How to Seal a Toilet Flange

Seal a toilet flange to prevent leaks.
Seal a toilet flange to prevent leaks. (Image: Jupiterimages/Polka Dot/Getty Images)

A water leak that seeps out from beneath your toilet is usually the sign of a bad flange seal. The flange is the opening in the bathroom floor that connects your toilet bowl to the sewer system. The space between the flange and the toilet bowl is sealed with a wax ring. These watertight rings also keep sewer gases from seeping out and into your home. You should seal a toilet flange to keep your home's plumbing up to code.

Things You'll Need

  • Putty knife
  • Rag
  • Rubbing alcohol
  • Flange bolts, nuts and washers
  • Plumber's putty
  • Adjustable wrench
  • Assistant (optional)

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Use a putty knife to clean the area around the flange. Scrape up any caulk, putty or wax with the putty knife. Apply rubbing alcohol to a rag and use it to help remove any stubborn caulk.

Insert a flange bolt in each side of the flange, with the threads pointing straight up. The bolts should be positioned 180 degrees from each other, in the three o'clock and nine o'clock positions when viewed from above. Slip the plastic washers over the ends of the bolts to keep them in position. If you do not have plastic washers, you can use a dab of plumber's putty.

Press the wax ring firmly in place around the flange opening.

Pick up the toilet bowl — have an assistant help you if the bowl is heavy — and hold it over the flange opening. Line up the bolts on the side of the flange with the holes in the base of the toilet.

Slowly lower the toilet bowl in place over the flange. Press the bowl snugly against the floor.

Slip the metal and plastic washers over the ends of the flange bolts. Tighten by hand until they're snug. Take an adjustable wrench and tighten one side an additional turn, then the other side. Continue alternating in this fashion for another three or four turns.


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