What Is A Sink Flange?

What Is A Sink Flange

Installing a sink correctly requires quite a few parts. Aside from the sink itself, you need a sink drain flange and plumbing parts, among other things. While you may not recognize the part based on its name, the sink flange is essential to your setup.

Perhaps you’re troubleshooting a leaking sink, and the guide you’re using says to check the sink flange. Or, maybe you’re following an installation manual, and it keeps referring to the sink flange. Either way, you’ll need to know what the flange is before the next steps in your project. 

What Is A Sink Flange On A Kitchen Sink?

Delta Faucet 72010-CZ Flange and Strainer, Kitchen Sink, Champagne Bronze

The flange on a kitchen sink can look quite different from the one you find on a bathroom sink. The flange is the part that connects the sink drain to the section of pipe beneath the sink, called the tailpiece. It’s made of metal and looks somewhat like a ring. 

It sits snugly around the drain like a collar and usually features a grid-like section covering the drain that looks similar to a strainer. When you run the faucet, this is what prevents the water from leaking out of the plughole. 

If the flange becomes damaged or loose, you might notice water damage in the cabinet underneath the sink. 

What Is A Bathroom Sink Flange?

Bathroom Sink Drain Replacement Parts, (Pop-up Drain Assembly) Include Chrome Plug and Flange - By PlumbUSA

Bathroom sink drain flanges do the same thing as those you’d find in a kitchen. However, since the drain set up in a bathroom sink is different from that in a kitchen, the drain flange looks a bit different. 

Generally, the flange is narrower and doesn’t have the netted strainer-like piece in the bottom, as the stopper has to fit into place. So, while the purpose is the same as a kitchen drain flange, a bathroom drain flange looks a bit different. 

The flange may feature threads on the bottom of it, where the other parts of the drain assembly connect beneath the sink. 

How Do You Replace A Sink Flange?

You’ll have to disconnect the drain assembly beneath the sink to replace a faulty sink flange or troubleshoot issues. Before you start, make sure you shut off the water supply to the sink you’re working on. 

Here’s what you’ll need:

  • Wrench (as required)
  • Silicone lubricant (as needed)
  • Putty knife

Generally, this involves unthreading the tailpiece beneath the sink. If the tailpiece is plastic, you can probably unthread it by hand. However, if the tailpiece is metal, it’ll probably take extra elbow grease to get the job done.

Once you unthread the tailpiece, unscrew the large nut fixing the drain flange in place. If it doesn’t budge, spray a generous coating of silicone lubricant over it before trying again. In scenarios where there’s rust holding it in place, try to tighten the nut before loosening it. This can help break the corrosion bond, allowing it to move freely. 

After removing the nut, push up the flange firmly from beneath the sink. Once it pops free, remove it from the drain. Then, scrape away the plumber’s putty from the sink drain before installing the replacement (or reinstalling the old one).

To replace a bathroom sink flange, the process is the same. However, you’ll have to remove the sink stopper before lifting the drain out. 

How Do You Install A Sink Flange?

Installing a sink flange is a straightforward process and should only take a few minutes. Here’s what you’ll need:

  • Drain assembly
  • Plumber’s putty
  • Pliers
  • Clean cloth

If you’re replacing an old drain flange, make sure you scrape away the old plumber’s putty before starting on the replacement. Once the area is clean, make a thin, long rope of plumber’s putty. Ensure it’s long enough to wrap around the drain hole. It should be about ¼-inch thick. 

Once you ensure the rope is long enough, set it into place around the drain hole. Press the new flange down firmly onto the hole. There’s some variation in how these flanges are secured in place, so refer to the manufacturer’s instructions for securing them. 

Generally, there’s a nut you have to screw on to tighten the nut in place, but it varies from one assembly to the next. If there is a nut to secure, start by tightening it with your hand. Tighten it with pliers to secure it in place, but don’t overtighten it, or you’ll strip the threads.

Before you move on, make sure the flange sits flat and snug against the bottom of the sink. Next, use a clean cloth to wipe away any excess plumber’s putty that oozed out from beneath the drain flange. 

After you finish cleaning up the excess putty, you can secure the bottom of the flange to the tailpiece beneath the sink. If you’re starting from scratch with new plumbing, follow the manufacturer’s instructions for attaching the tailpiece and subsequent plumbing.