A drain flange is the finished, visible part around your drain hole that helps seal the joint between the tub and the drain assembly below. If you notice it is no longer sealing properly and water is entering this area, you need to replace and reseal this flange immediately. Water leaking beneath your tub can become a major problem before you know it. This replacement is fortunately easy to do and requires only one special tool: a tub drain wrench.
Step 1 - Remove the Drain Cover
The drain flange is usually hidden by a cover that acts both as a strainer and ornamental concealment. It’s held in place by a single screw, so take a screwdriver, loosen it, and lift the cover out of the way.
Step 2 - Remove the Drain Flange
This step is what makes use of a tub wrench, which looks something like the rook on a chess board. Each end is sized to fit a different type of drain, so test each to see which fits best before you use it.
Set the tool in the tub shoe so that the teeth grab onto the crosspieces in the drain. Then, turn the tub wrench counterclockwise by gripping the shaft with an adjustable wrench and applying force. Pull this piece out of the hole as it gets unscrewed completely.
Step 3 - Clean the Drain Opening
Dampen a clean rag with acetone and wipe down the area around the drain. Scrub if needed to remove all dirt, debris, and old plumber's putty that may interfere with the new seal.
Step 3 - Seal the New Drain Flange
The plumber’s putty plays a vital role in this repair as it is what makes the drain flange watertight. Roll out a rope of putty about the thickness of an ordinary pencil and spread it below the rim of the flange, letting it fill the entire underside. Then, place the new flange in the hole and screw it down with the tub wrench in a clockwise direction. The putty will squish out of the gap as you tighten it down; this seals the flange to the tub. Wipe away the excess after you're finished.
Step 4 - Fit the Cover and Test
Screw the cover back onto the drain and prepare to test your work. Fill the tub half full with water, stop up the drain, and then watch the edges of the refitted flange for bubbles. Now it should hold the water and the tub should drain only when you release the stopper.
Mark Vander Sande, professional plumber, contributed to this article.