PVC Toilet Flange Replacement: How to Cut Out a Bad Flange and Set a New One
I'm Ricky Cox, master plumber with Sewer Studs Plumbing & Drain. This is our most-watched how-to video for a reason: a toilet flange is a small part that causes big problems when it fails.
On this job, the problem showed up when I went to set the toilet. The bolts were spinning in the flange and just wouldn't tighten down. When the bolts won't hold, the toilet can't hold either — so the fix isn't a new bolt or a bigger washer. The old flange has to come out and a new one has to go in.
Step One: Pull the Toilet
Every flange replacement starts the same way: the toilet comes off first. That exposes the flange so you can see exactly what you're dealing with and work on it without the bowl in the way.
Step Two: Cut the Old Flange Out From Inside the Pipe
The way we cut this flange out is with an inside pipe cutter. It cuts the pipe right below the flange, from the inside, so the flange comes out clean without tearing up the pipe below it.
Once the old flange is cut out, look inside the pipe. On this one there was old glue left in the pipe, so I took sandpaper and cleaned the inside of the pipe up before the new flange went anywhere near it. A new flange glued over a rough, glue-covered surface is a leak waiting to happen — clean pipe first, then glue.
Before anything gets glued, dry-fit the new flange and make sure it fits correctly. Glue gives you one shot; the dry fit is where you find out if something's off.
Step Three: Prime, Glue, and Anchor the New Flange
The new flange on this job is a 4x3 PVC closet flange with a stainless steel ring.
The install goes in this order:
- Prime the inside of the pipe and the outside of the flange.
- Glue the inside of the pipe and the outside of the flange.
- Push the flange down and give it a quarter turn — that spreads the glue and seats it.
- Anchor it to the floor with Tapcon screws once it's glued in, so the flange is fixed to the floor and not just to the pipe.
That stainless ring matters for the problem that started this job: the toilet bolts need a ring that will actually hold them when you tighten down.
Step Four: Reset the Toilet on a New Wax Ring
With the new flange glued in and anchored down, the toilet goes back on:
- Put a new wax ring on the bottom of the toilet — the old one doesn't get reused.
- Set the toilet down onto the flange.
- Tighten down the bolts — and this time they hold, because they're tightening against a sound flange.
- Put the bolt caps on.
- Hook the water supply line back up.
- Turn the water on and check for leaks before you call it done.
On this job the toilet set clean with no leaks, and the last step was caulking around the base of the toilet.
Why This Matters More Than It Looks
A flange that won't hold its bolts leaves you with a toilet that rocks, and a rocking toilet works its wax seal loose — which is how a small hardware problem turns into water under the floor. If your toilet moves when it shouldn't, our guide to related toilet work is a good next read, and the same failure shows up in real jobs in our toilet pull and reset vlog from Carrollwood.
Thinking About Toilet Work at Your House?
A flange replacement is one piece of toilet work. Our fixture installation page covers how we handle toilet installs and the change-order items that can surface once a toilet is pulled — the flange and the wax ring are exactly that kind of item. If the problem is smaller — a running toilet, a flush that isn't right — start with small plumbing repairs, and if your toilet uses a pressure-assist flush, our pressure-assist cartridge guide walks through that fix. We serve homeowners across Tampa Bay — see our Tampa plumber page.
Frequently Asked Questions
How do you know a toilet flange needs replacing instead of repairing?
On this job the tell was simple: when I went to set the toilet, the bolts spun in the flange and wouldn't tighten down. If the flange can't hold the bolts that hold the toilet, the toilet can't be set solid — and the flange gets replaced.
What kind of flange did you install?
A 4x3 PVC closet flange with a stainless steel ring. It was dry-fit first to confirm the fit, then primed and glued, pushed down with a quarter turn, and anchored to the floor with Tapcon screws.
Why clean the inside of the pipe before gluing the new flange?
Because cutting the old flange out left glue inside the pipe. Sanding that clean gives the primer and glue a proper surface to bond to, so the new flange seals instead of sitting on old residue.
Do you reuse the wax ring when you reset the toilet?
No. This reset went on a new wax ring, set on the bottom of the toilet before the toilet went down onto the new flange. After the bolts, caps, and supply line, we turned the water on and checked for leaks.
Ready to Talk About Your Toilet?
If your toilet rocks, leaks at the base, or the bolts won't tighten down, we'll give you a straight answer and a firm quote. Call Sewer Studs Plumbing & Drain at (813) 680-2284, Monday through Friday, 8 AM to 5 PM.