What a wax seal does and why it fails

A wax seal is a ring of wax that sits between the base of your toilet and the flange — the pipe fitting in the floor. It creates a watertight seal so water from the bowl doesn't leak into the subfloor or crawl space below. Over time, the wax hardens and cracks, usually after 20 to 30 years, or sooner if the toilet rocks or the house settles.

You'll know the seal is failing if you see water pooling around the base of the toilet, smell sewage odours near the toilet, or notice soft spots in the floor around it. Once the seal fails, water seeps down and can rot the subfloor, damage joists, and create mould. Replacing the seal stops the leak and prevents structural damage.

Key Takeaways

  • You must remove the toilet completely to access and replace the wax seal, which takes two to four hours for most people.
  • The job requires turning off the water supply, draining the bowl and tank, unbolting the toilet, and lifting it straight up to break the old seal.
  • A new wax ring costs $5 to $15, but you may also need a new flange or shims if the old one is damaged or the toilet sits uneven.
  • The toilet must sit level on the flange for the new seal to work; shims under the base correct minor slopes in the floor.
  • After reinstalling, you must caulk around the base to prevent water from running under the toilet and bypassing the seal.

Tools and materials you'll need

Gather these items before you start: an adjustable wrench or socket set, a screwdriver (usually Phillips), a putty knife or old chisel, a level, a bucket, rags or towels, and a sponge. You'll also need a new wax ring — buy one that matches your flange size, usually 3 or 4 inches. If the flange is cracked or sits below floor level, pick up a repair flange or shims as well.

Wear gloves and have a trash bag ready for the old wax and bolts. If you're uncomfortable working with sewage, this is the moment to call a plumber; the job is straightforward but messy. If you proceed, keep the bathroom door closed and ventilate well.

Shutting off water and draining the toilet

Locate the shutoff valve behind or below the toilet tank and turn it clockwise until the water stops flowing. Flush the toilet to empty the tank. If water still sits in the bowl, use a sponge or small cup to remove it into a bucket — you need the bowl as dry as possible before you lift the toilet.

Disconnect the water supply line from the bottom of the tank by turning the nut counterclockwise with an adjustable wrench. Have a rag ready to catch any remaining water. If the line is old and brittle, replace it while you have the toilet off; new supply lines cost $10 to $20 and prevent future leaks.

Removing the old toilet and wax seal

Look at the base of the toilet where it meets the floor. You'll see two bolts — one on each side — that hold the toilet to the flange. These bolts sit inside plastic caps or trim rings. Pry off the caps with a screwdriver, then unbolt the toilet by turning the nuts counterclockwise with a wrench. If the bolts are corroded and won't turn, spray them with penetrating oil and wait 10 minutes.

Once both bolts are loose, straddle the toilet, grip the tank firmly, and rock it gently side to side to break the wax seal. Lift straight up — the toilet is heavy (40 to 50 pounds), so use your legs, not your back. Set it on its side on a tarp or old towels to protect the floor and prevent the bowl from cracking. Do not set it upright on the floor; the rim can chip.

You'll now see the old wax ring stuck to the flange. Scrape it off with a putty knife, working slowly to avoid damaging the flange. Remove all wax, debris, and old caulk. Inspect the flange: if it's cracked, sits below floor level, or rocks when you press on it, it needs repair or replacement before you install the new seal.

Installing the new wax seal and toilet

Press the new wax ring firmly onto the flange, centring it over the opening. The wax should stick to the flange without falling off. If the toilet sits uneven on the floor, place shims under the base before you set it down — this keeps the wax seal compressed evenly. You can buy plastic shims at any hardware store, or use thin wood shims and trim them flush later.

Lower the toilet straight down onto the flange, aligning the bolt holes with the bolts sticking up. Push down firmly and evenly so the wax compresses. The toilet should sit level; check with a level placed on the tank rim. If it rocks, lift it off, add or adjust shims, and try again. Once it's level, insert the bolts through the holes and hand-tighten the nuts. Do not over-tighten — you only need them snug enough that the toilet doesn't move. Over-tightening can crack the porcelain.

Reconnect the water supply line and turn the shutoff valve back on. Let the tank fill, then flush once to check for leaks around the base. If water pools under the toilet, the seal may not be seated properly; you'll need to remove and reinstall it.

Sealing and finishing

Once the toilet is find and the tank fills without leaking, caulk around the base with silicone caulk. This prevents water from running under the toilet and bypassing the wax seal. Run a bead of caulk around the entire perimeter where the toilet meets the floor, then smooth it with a wet finger. Caulk dries in 24 hours; don't use the toilet heavily until then.

If you used wood shims, trim them flush with the toilet base using a utility knife or handsaw. Snap off the plastic caps and bolt covers, then press them back over the bolts to hide them. The toilet should now sit level, stable, and sealed.

When to call a plumber instead

If the flange is cracked or broken, the subfloor is soft or rotted, or the toilet won't sit level even with shims, stop and call a plumber. A damaged flange or subfloor must be repaired before a new wax seal will work. If you're unsure whether the flange is salvageable, a plumber can assess it in 15 minutes and quote the repair.

If you remove the toilet and find water damage under it, or if the floor feels spongy, the subfloor has absorbed water and may need replacement. This is beyond a wax seal swap and requires structural work. A plumber or contractor can tell you the scope and cost.

Frequently Asked Questions

Can I replace a wax seal without removing the toilet?

No. The wax ring sits between the toilet base and the flange, so you must lift the toilet to access it. Any product claiming to seal a wax ring without removal is not a real repair.

What's the difference between a wax ring and a wax-free seal?

Wax rings are traditional and cost $5 to $15. Wax-free seals (rubber or foam) cost $15 to $30 and are easier to reuse if you remove the toilet again. Both work equally well if installed correctly. Wax-free seals are a good choice if you think you'll need to access the toilet again in the next few years.

How long does a wax seal last?

Most wax seals last 20 to 30 years. They fail sooner if the toilet rocks, the house settles unevenly, or the flange is damaged. Once replaced, a new seal should last another 20 to 30 years if the toilet stays stable and level.

What if water leaks after I reinstall the toilet?

Check that the toilet is level and the bolts are snug but not over-tightened. If it still leaks, the wax may not have compressed evenly. You'll need to remove the toilet, scrape off the old wax, and install a new seal. This is common on the first try; don't be discouraged.

Do I need to caulk around the toilet base?

Yes. Caulk prevents water from running under the toilet and bypassing the wax seal. Use silicone caulk, not acrylic, because it resists moisture better. Run a bead around the entire perimeter where the toilet meets the floor.