The flange comes off by unbolting it from underneath the sink

The sink flange is the ring that sits on top of your sink opening where the garbage disposal connects. To remove it, you work from below the sink: unbolt the three or four bolts that hold the flange to the sink rim, then push the flange up and out from the top. The whole job takes 15 to 30 minutes if the bolts turn freely, longer if they are stuck or corroded.

You will need a wrench or socket set, a screwdriver, and possibly penetrating oil if the bolts have not been disturbed in years. The disposal itself does not have to come off first, though it makes the work easier if you remove it. If you are replacing the flange because it leaks, you will also need plumber's putty and a new flange kit.

Key Takeaways

  • The flange bolts are accessed from under the sink, and you turn them counterclockwise to loosen them.
  • If bolts are stuck, spray them with penetrating oil and wait 15 to 30 minutes before trying again.
  • Once all bolts are out, push the flange up through the sink opening from below to remove it.
  • Removing the disposal first makes the job less cramped, though it is not required.
  • If the flange is leaking, you will need to scrape out old putty and explore new putty to the replacement flange before reinstalling.

Gather your tools and turn off the power

Before you start, flip the breaker that controls the garbage disposal to the off position. Even though you are not running the disposal, an accidental bump could start it while your hands are near the opening. Leave the breaker off for the entire job.

Collect a wrench or socket set that fits your flange bolts (usually 1/2 inch), a flathead screwdriver, a flashlight, and a bucket or towel to catch water that may drip from the P-trap. If the bolts are old or corroded, have penetrating oil on hand—WD-40 or a similar product works. Wear work gloves to protect your hands from sharp edges under the sink.

Remove the disposal if you have room to work

Removing the disposal first is optional but recommended. It gives you much more space to reach the flange bolts and turn the wrench. To remove the disposal, disconnect the electrical cord (or have an electrician do it if it is hardwired), unbolt the disposal from the mounting ring, and set it aside on a towel.

If the disposal is hardwired instead of plugged in, or if you are not comfortable working with electrical connections, you can skip this step and work around the disposal. Just know that the space will be tight and you may need a smaller wrench or a socket wrench to reach the bolts.

Locate and loosen the flange bolts from underneath

Lie on your back under the sink or crouch in the cabinet. Shine your flashlight up at the flange. You will see three or four bolts arranged in a circle around the underside of the flange. These bolts go through the flange and into the sink rim. Use your wrench to turn each bolt counterclockwise.

Turn slowly and steadily. If a bolt does not budge after a few tries, stop and spray it with penetrating oil. Let the oil soak for 15 to 30 minutes, then try again. Do not force a stuck bolt—you risk stripping it or breaking the bolt, which makes removal much harder. Once all bolts are loose, unscrew them the rest of the way by hand and set them aside in a safe place.

Push the flange out from below or pull from above

With all bolts removed, the flange is held in place only by the plumber's putty seal around its underside. From below the sink, push the flange upward firmly. It should pop up through the sink opening. If it does not move, use a flathead screwdriver to gently pry around the edge of the flange from below, working your way around the ring until it lifts free.

Once the flange is loose, you can also reach down from the top of the sink and pull it up while pushing from below. The flange will come out with old putty still stuck to it. Set it on a towel to avoid making a mess.

Scrape away old putty if you are replacing the flange

If the flange is cracked, corroded, or leaking, you will replace it with a new one. Before you install the new flange, scrape all the old plumber's putty off the underside of the sink opening. Use a flathead screwdriver or a putty knife to scrape the rim clean. The new putty will not seal properly if old putty is still there.

Wipe the rim with a damp cloth to remove putty crumbs and let it dry. The rim should be clean, dry, and smooth before you explore new putty to the replacement flange. If you are keeping the old flange and just need to reseal it, clean it the same way.

Reinstall the flange with fresh putty

Roll a rope of plumber's putty about the thickness of a pencil and press it around the underside of the flange rim—the part that will sit against the sink opening. Lower the flange back through the sink opening from the top and press it down firmly so the putty squeezes out and creates a watertight seal.

From underneath, insert the bolts back through the flange and into the sink rim. Tighten them in a crisscross pattern (like tightening a car wheel) so the flange sits evenly. Tighten firmly but do not over-tighten, which can crack the sink or strip the bolts. Wipe away excess putty that squeezes out from around the flange with a damp cloth.

Reinstall the disposal and test for leaks

If you removed the disposal, bolt it back onto the mounting ring and reconnect the electrical cord or have an electrician reconnect it if it is hardwired. Turn the breaker back on. Run water into the sink for 30 seconds and check underneath for leaks. Water should not drip from the flange seal or from any bolt holes.

If you see a small drip, tighten the bolts slightly more and retest. If water is still leaking after tightening, the putty seal may not be complete. In that case, you will need to remove the flange again, add more putty, and reinstall. If leaking continues after a second attempt, the sink rim itself may be damaged and you should call a plumber.

Frequently Asked Questions

Can I remove the flange without removing the disposal?

Yes. The space under the sink will be cramped, but you can reach the bolts with a socket wrench or a wrench with a short handle. Work slowly and use a flashlight so you can see what you are doing. Removing the disposal makes the job much easier, but it is not required.

What if one of the bolts breaks while I am loosening it?

If a bolt snaps, the broken piece will still be threaded into the sink rim. You may be able to remove it with locking pliers or a bolt extractor tool. If you cannot remove it yourself, a plumber can drill it out and install a new bolt. Do not force it—you risk damaging the sink rim.

How do I know if the flange needs to be replaced?

If water leaks from under the sink when you run the disposal, the flange seal has failed. If the flange itself is cracked, corroded, or has visible damage, replace it. A flange that is straightforward loose can often be resealed with new putty without replacing it.

Is plumber's putty the only way to seal a flange?

Plumber's putty is the standard and most reliable method. Some people use silicone caulk instead, but putty is easier to remove later if you need to access the flange again. Never use regular caulk or sealant—it will not hold up to water and temperature changes.

Do I need to call a plumber for this job?

If the bolts turn freely and you are comfortable working under a sink, this is a straightforward DIY job. Call a plumber if bolts are severely stuck, if the sink rim is cracked, if you are not sure about the electrical disconnect, or if leaking continues after you reinstall the flange.