Replacing a toilet flange isn’t always as simple as swapping out an old part for a new one. In the YouTube video “Replacing a Toilet Flange | Plumbing 101,” I walk through a real-life scenario: removing a failing flange, discovering potential cracks in the PVC, and installing a new, properly anchored flange. Below, you’ll get a detailed look at every step, including how to prepare, which tools to use, and key mistakes to avoid. If you’re dealing with a wobbly toilet or suspect your flange is past its prime, this guide will help you tackle the project with confidence.
A faulty toilet flange can lead to water leaks, bad odors, and structural damage around the bathroom floor. In this post, we’ll cover the process of removing your toilet, diagnosing flange damage, and installing a new flange that provides a watertight seal. Follow these steps, and you’ll restore your toilet’s stability and performance, all without having to rip up more of your floor than necessary.
Why a Properly Installed Flange Matters
A toilet flange is the critical connection between the drain pipe and the toilet itself. It creates the seal that prevents water and sewer gas from escaping into your home. When the flange is broken, cracked, or set too low or high, the toilet can wobble, leak, or fail to flush efficiently. In the worst cases, you might have to jackhammer concrete or replace sections of pipe—usually a last resort if the issue extends into your subfloor or drainage system.
Common signs of a failing flange include:
- Toilet movement or noticeable rocking
- Water seeping around the toilet base
- Persistent sewer smells despite a clean bowl and wax seal
- Visible cracks or metal corrosion around the old flange
The best solution is to replace a damaged flange promptly. A stable, properly positioned flange means no leaks, no odors, and no headaches down the line.
Gathering the Tools and Supplies
Before you begin, stock up on the essentials. Having the right tools on hand will save time and reduce frustration:
- Adjustable wrench or a small ratchet for the closet bolts
- Wet/dry vacuum for removing standing water in the toilet bowl or trap
- Putty knife or scraper to clear old wax residue
- Safety glasses and work gloves (especially if you’ll be dealing with concrete or debris)
- Replacement flange sized for your drain pipe (often 3-inch or 4-inch PVC)
- Toilet anchor bolts
- Drill and bits for concrete or wood anchoring (depending on your subfloor)
- PVC primer and cement if you’re working with a PVC flange
- Inflatable test ball or plug (optional but useful for preventing debris from going down the drain)
Make sure the replacement flange you buy matches your existing drain material and diameter. Some flanges fit inside the pipe, while others fit over it. If the subfloor is concrete, you may need masonry bits to secure the new flange.
Step 1: Turn Off Water and Drain the Toilet
You can’t replace a flange without removing the toilet first. Before any disconnections, turn the toilet’s shutoff valve clockwise to stop water flow. Next, flush the toilet to remove as much water as possible from the bowl and tank. There may still be some residual water, so:
- Use a wet/dry vacuum to suck out the remaining water in the bowl.
- Disconnect the supply line from the tank by loosening the coupling nut with a wrench.
Removing as much water as you can ensures no messy spills when you lift the toilet off the flange.
Step 2: Remove the Toilet
Locate the two bolts (closet bolts) on either side of the toilet base. These hold the toilet to the flange. Use a wrench or socket to remove the nuts. If they’re corroded or stuck, you might need penetrating oil or a small hacksaw to free them.
Once the nuts are off, gently rock the toilet from side to side to break the wax seal. Lift the toilet straight up and set it aside on a protective surface like cardboard or old towels. Take care not to tilt or drop it—porcelain can crack.
Step 3: Inspect the Old Flange
With the toilet removed, examine the flange. Look for:
- Hairline or visible cracks in the plastic or metal ring
- Corroded metal edges
- Broken bolt slots that prevent the toilet bolts from seating properly
- Separation between the flange and the drain pipe
In many cases, you’ll see an old wax ring that’s worn out or partially stuck. Scrape off the leftover wax with a putty knife to get a clear view of the flange. If you notice a significant crack or gap, you know the flange needs replacing.
Step 4: Remove the Existing Flange
If the old flange is in decent shape (no cracks), you could consider a repair ring. But if you spot clear damage, you’ll need to remove it entirely:
- Check for Screws or Bolts: Some flanges are screwed into the subfloor or concrete. Unscrew or pry them up carefully.
- Cut Away the Flange: For PVC flanges that fit inside a 4-inch pipe, you can use a special internal pipe cutter or carefully slice the flange to peel it out. Wear safety glasses to protect from flying debris.
- Test Ball or Plug: To prevent plastic chips and dirt from entering the main drain, insert a test ball (an inflatable plug) into the pipe. If you don’t have a test ball, place a rag in the drain, but remember to remove it later.
In certain tricky situations—like if the flange is cast iron or deeply embedded in concrete—you might need more specialized tools or a professional plumber. In the video, we initially thought we’d have to jackhammer part of the floor, but once we investigated more closely, we found a simpler approach.
Step 5: Prepare the Surface and Dry Fit
Once the old flange is out, vacuum any debris and ensure the subfloor or concrete is clean. The new flange must sit flush (or just above) the finished floor for a proper seal. In some older installations, the flange is set below the floor level:
- If the flange is lower than the finished floor, you may need to add flange extenders or use a thicker wax ring.
- If your new flooring is thicker than the old one, confirm the flange sits at the right height.
Dry fit the new flange over or inside the drain to confirm it aligns with your toilet’s bolt holes. Also check that the bolt slots will be parallel to the back wall, so the toilet sits straight.
Step 6: Attach the New Flange
For a PVC flange, use a combination of PVC primer and cement. This typically involves:
- Mark the Orientation: Position the flange so the bolts align symmetrically with the bathroom walls.
- Prime and Cement: Apply primer to both the outside of the drain pipe and the inside of the flange hub. Then apply cement in the same areas, push the flange down firmly, and give it a slight twist to ensure an even bond.
- Secure to the Floor: Insert anchor bolts or screws through the flange’s mounting holes into the subfloor or concrete. If drilling into concrete, use masonry bits and concrete anchors. Tighten until the flange is snug and flat.
Let the PVC cement cure according to the manufacturer’s instructions—often just a few minutes is enough for a strong hold.
Step 7: Choose the Right Wax Ring (or Wax-Free Seal)
A correct seal between the toilet base and flange prevents leaks and odors. Standard wax rings are fine if the flange is even with or slightly above floor level. If the flange is lower, consider a thicker wax ring or one with a plastic funnel extension. Wax-free toilet seals made of rubber or foam are another option—they’re less messy and can be repositioned if needed.
Step 8: Set the Toilet
With the flange secure, place two new closet bolts in the flange’s slots. Position them so they won’t shift when you lower the toilet. Then:
- Center the Wax Ring: Press the new wax ring gently onto the bottom of the toilet outlet. Alternatively, you can place the ring on the flange itself—just be careful when lowering the toilet to avoid misalignment.
- Lower the Toilet: Carefully align the bolt holes on the toilet with the closet bolts and lower it straight down. Rock gently to compress the wax ring. The toilet should rest firmly on the floor.
- Secure the Nuts: Slide washers and nuts onto the bolts. Tighten them in small increments, alternating sides to keep the toilet level. Don’t overtighten—porcelain can crack.
- Check for Rocking: If the toilet still wobbles, insert plastic shims around the base before final tightening. Cut off any excess shim material.
Step 9: Reconnect the Water and Test
Attach the water supply line back to the tank’s fill valve and open the shutoff slowly. Watch as the tank fills; if there are no leaks or drips, flush a few times to ensure everything works smoothly. Check for:
- Water around the base: Indicates a poor wax seal or flange alignment.
- Leaking supply line: Could mean the coupling nut isn’t tight enough or needs a new washer.
- Strange noises: Sometimes a loose fill valve or supply line can cause vibration.
If you see no issues, congratulations—your new flange is installed!
Troubleshooting and Tips
- Concrete Floors: When installing on concrete, anchor the flange firmly with masonry screws or tapcons. This ensures the flange—and toilet—won’t shift over time.
- Flange Depth: If the flange is more than 1/4 inch below the finished floor, consider a flange extender ring. Stacking multiple wax rings can work in a pinch, but it’s more reliable to bring the flange closer to floor level.
- Repair Flange vs. Full Replacement: If the PVC pipe itself is in good shape and only the metal ring is corroded, a repair ring can solve the problem without removing the entire flange. Be sure to confirm no cracks in the pipe or subfloor.
- Double-Check Bolt Orientation: After gluing the flange, make sure the toilet bolts line up exactly where you need them. Quick adjustments are possible if the cement hasn’t fully set, but you have to act fast.
Frequently Asked Questions
Q: Can I reuse the old wax ring if it looks okay?
A: It’s generally best to replace the wax ring every time you lift a toilet. Old wax won’t reseal reliably, and the cost of a new ring is minimal compared to the hassle of fixing a leak.
Q: What if I see hairline cracks in the drain pipe?
A: Hairline cracks can become bigger problems down the road. If the crack is superficial, you may use a repair epoxy or sealant. Otherwise, consult a plumber for options like partial pipe replacement.
Q: Is it acceptable to install an additional layer of flooring around the flange?
A: If you add flooring (e.g., tile or hardwood), the flange needs to remain flush with the new surface. That might mean installing a flange extension or removing and reinstalling a new flange at the correct height.
When to Call a Professional
While many DIY enthusiasts can handle a routine flange replacement, certain scenarios require professional help:
- Extensive subfloor damage: If water leaks have rotted or molded the subfloor, you might need to rebuild the area before installing a new flange.
- Cast iron or lead drain pipes: These older materials can demand specialized cutting or joining techniques that go beyond a typical PVC replacement.
- Slab homes: When your drain lines run through concrete slabs, repairs often involve jackhammering and repouring concrete—better left to a pro with the right equipment.
Final Thoughts
In “Replacing a Toilet Flange | Plumbing 101,” we tackled a straightforward but essential plumbing job that can quickly escalate if you find cracks beneath the surface. The key is careful diagnosis, proper preparation, and precise fitting of the new flange. Once everything is in place, the new toilet should sit firmly, free from leaks or rocking, and give you peace of mind for years to come.
Replacing your flange not only stops immediate issues like leaking or bad odors—it also preserves the integrity of your bathroom floor and subfloor. If you ever hear a slight creak or notice water around the base, don’t wait for the problem to worsen. A solid flange replacement is an investment that pays off in a stable, well-sealed toilet.
