How to Remove a Sink Drain Flange: A 3-Step Guide

by Team HomeServe
Closeup overview of stainless steel sink drain shows where the circular sink flange inserts into the sink basin.

Removing a Sink Drain Flange at a Glance

  • Step 1: Remove coupling nut
  • Step 2: Remove locknut
  • Step 3: Pull out drain flange

Removing a sink flange to replace or repair it is a reasonably straightforward DIY task that you can accomplish without any expertise. However, residue and rust buildup can often turn an easy plumbing job into a frustrating experience.

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Fortunately, there are some simple ways to remove a sink flange, even if it's firmly stuck in the assembly. Use these step-by-step instructions to remove a sink drain flange.

How Do You Remove a Sink Flange?

Before you begin, empty everything from underneath the sink and place a cushion or two on the floor for comfort. It's also worth switching off the water supply to the faucet so that you don't get a nasty surprise if someone turns the tap on while you're working under the sink.

Removing a sink flange should be a quick task, even if it’s wedged in tightly. Here’s what to do:

Underside view of kitchen sink shows where the cylindrical sink flange connects to the sink basin.

Step 1: Remove the Coupling Nut

The coupling nut is a large ring-shaped nut that joins the flange basket to the drain pipe. Grasp it firmly with a set of slip-joint pliers and twist it to the left to loosen it. If it doesn't budge, try turning it in the opposite direction. Doing this can break any residue or rust that's jamming the nut, letting you unscrew it more easily. Loosen it until you can remove it from the threads.

Step 2: Remove the Locknut

Using your slip-joint pliers, twist the locknut between the flange assembly and the bottom of the sink to remove it. If the flange is rusty or caked with residue, this may cause it to spin.

Allowing the flange to spin while you loosen the locknut could lead to damage, so it's important to hold it still while you work. You can do this by inserting the handles of a pair of pliers into two of the holes in the drain basket. Place a screwdriver or other rigid tool between the handles, and ask a helper to hold it in place to stop it from turning.

Step 3: Pull Out the Drain Flange

Finally, you can use a utility knife to cut away any hardened plumber's putty holding the flange in place and gently pry the flange upwards. Once you've chipped away any putty causing the flange to stick, you should be able to pull it out by hand.

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How Do You Remove a Rusted Sink Flange?

Rust is one of the most common reasons people find it difficult to remove their old sink flange. One of the easiest and most effective ways to break down the rust is to spray the threading thoroughly with silicone lubricant and leave it to soften. The package should tell you how long you need to let it sit. If you still can't loosen it, try tightening the nut instead. While it may sound counterintuitive, this can break the stubborn rust and solve the issue.

If lubricant doesn't work or the issue is compounded by a thick layer of putty holding the flange in place, you may need to apply a bit more force to get it out. Place a block of wood under the sink against the bottom of the flange and hit the wood firmly with a hammer. The sudden force should be enough to break any stubborn rust or putty and loosen the flange.