How do I fix a broken toilet flange?

The closet flange sits where the toilet meets the floor. It does two jobs at once. First, it bolts the toilet down. Two closet bolts rise up through slots in the flange ring and pass through the holes in the base of the toilet, where nuts hold everything tight. Second, the flange connects the toilet's outlet to the drain pipe that carries waste away. A wax ring (or a rubber seal) sits between the toilet and the flange and forms a watertight, airtight seal.

The flange is usually screwed to the subfloor and glued or fitted to the top of the drain pipe. Most are made of PVC, ABS plastic, or metal such as cast iron or brass. The ring should sit level with or just above the finished floor. When it sits too low, the wax ring cannot reach the toilet to make a good seal.

Because the flange both holds the toilet and seals the drain, a small failure here causes outsized trouble. A loose bolt slot lets the toilet move, and movement breaks the wax seal. Once the seal is gone, water and gas escape every time the toilet is used.

A failing flange shows a few clear signs. Catching them early keeps a cheap repair from turning into rotted subfloor or a ceiling stain below.

• A rocking or wobbly toilet. If the bowl shifts when you sit or lean, the toilet is no longer held firmly. The cause is often a cracked flange or stripped bolt slots, though loose nuts can do it too.
• Water around the base. A puddle or a damp ring at the foot of the toilet after a flush points to a broken wax seal, which a moving or cracked flange almost always causes. The EPA notes that household leaks waste nearly 1 trillion gallons of water nationwide each year, so a small base leak is worth fixing fast.
• A sewer smell. That airtight wax seal also blocks sewer gas. When the seal fails, the rotten-egg odor of hydrogen sulfide can drift up around the base.

Rule out look-alikes first. Tank or supply-line drips run down the outside and can fool you. Condensation on the tank in a humid bathroom can also drip to the floor. Wipe everything dry, then watch where the water returns. If it shows up at the base only after a flush, the flange and wax seal are the likely cause.

Match the fix to the failure. Picking the wrong one wastes a trip and may not hold.

1. 1Broken bolt slots: use a flange repair ring. The most common failure is a cracked or snapped slot where a closet bolt anchors. You do not always have to cut out the whole flange. A metal or plastic repair ring, such as the Oatey Fix-It ring, lays over the old flange and gives you fresh, solid bolt slots. Oatey makes the same point in its repair guidance: "If the flange is cracked or broken, you may be able to repair it with a repair ring or replace it entirely." Set the ring so its slots line up with the toilet, then screw it down to the subfloor.
2. 2Flange sits too low: use a spacer or extender. New tile or a new floor often raises the finished surface above the old flange. A flange that sits more than about a quarter inch below the floor leaves the wax ring stretching too far to seal. A stackable flange spacer or extender ring lifts the surface up to the right height. Stack the spacers, seal each layer per the maker's instructions, and bolt through.
3. 3Cracked, badly corroded, or loose: replace the flange. If a metal flange has rusted thin or a plastic one is split through the ring, it needs to come out. A full replacement removes the old flange and fits a new one to the drain pipe, glued for plastic or fastened for metal. This is the most involved option and the one most likely to call for a plumber, since it can mean working inside the drain line.

When in doubt, a sturdy repair ring is the safe first move for broken slots, and a spacer is the right answer for a flange that is simply too low.

Work in order. Most of the difficulty is in handling the toilet, not the flange itself.

1. 1Shut off the water. Turn the supply valve behind the toilet clockwise until it stops. Flush and hold the handle to drain the tank, then sponge out the rest of the water from the tank and bowl.
2. 2Disconnect and remove the toilet. Unhook the supply line. Pop the caps off the closet bolts, loosen the nuts, and lift the toilet straight up. Set it on a towel or cardboard. Plug the open drain with a rag to block gas while you work.
3. 3Clean and assess the flange. Scrape off the old wax ring completely with a putty knife. Now look at the flange. Are the bolt slots broken? Is the ring cracked or rusted? Does it sit below the floor? Your answer points to the repair ring, spacer, or full replacement above.
4. 4Fit the repair. Install the repair ring, spacer, or new flange per the product instructions. New closet bolts should stand straight up in the slots, set across from each other so the toilet lands square.
5. 5Set a new wax ring. Never reuse an old one. Press a fresh wax ring onto the flange (or onto the toilet's outlet horn). A wax ring with a built-in plastic funnel gives extra guidance into the drain. Oatey advises that you "do not use the toilet until the wax ring has set," so plan to leave it undisturbed.
6. 6Reseat the toilet. Lower the bowl straight down over both bolts in one motion, then press down with your weight to compress the wax. Add washers and nuts and tighten them gently and evenly. Do not overtighten, since too much force can crack the porcelain base.
7. 7Shim if needed. If the toilet still rocks on an uneven floor, slide thin plastic shims under the base, then snug the nuts again. Trim the shims and apply a bead of caulk around the base, leaving a small gap at the back so a future leak can show itself.
8. 8Test. Turn the water back on, let the tank fill, and flush several times. Watch the base for any sign of water. A toilet uses a real share of household water, since the EPA reports toilets account for about 30 percent of a home's indoor water use, so a clean seal matters.

Many Phoenix homes are built slab-on-grade, meaning the floor sits on a concrete slab with the drain pipes cast right into it. That setup puts the flange at concrete level and makes a clean repair ring or spacer fix especially handy, because cutting into a slab to replace a flange is hard, dusty work. Older metal flanges in these homes also corrode over the years, and the region's hard water speeds up mineral buildup and wear on toilet parts in general.

You can handle most flange jobs yourself if you are comfortable lifting a toilet and you find broken bolt slots or a low flange. A repair ring, a spacer, a new wax ring, and an hour or two are usually all it takes. Call a licensed plumber when the flange is set into a concrete slab and needs full replacement, when the drain pipe itself is cracked, when the subfloor around the flange is soft or rotted, or when the toilet still leaks after a careful reseat. Those cases can mean opening the slab or the drain line, which is beyond a basic swap.

If you are still tracing the problem, see our guide on a toilet leaking at the base to confirm the source. If the toilet itself is old, cracked, or wasteful, the cost to replace a toilet walks through whether a full swap makes more sense than another repair.