Question: If a drain has a rubber grommet, do I need plumber’s putty?
Answer: Usually, no. If the drain uses a rubber grommet, that gasket is meant to make the seal.
You pulled the drain apart to clean it. You also found old plumber’s putty there. That can be confusing.
Many older drain installs used putty under the flange. That was common for metal sink drains.
But newer drains often use rubber, foam, or silicone gaskets. These parts seal when compressed.
Adding putty can sometimes hurt the seal. It can stop the gasket from sitting flat.
That can leave a small path for water. A small path can become a slow leak.
Always check the drain instructions first. Some drains still call for putty under the top flange.
Oatey says plumber’s putty is used between rigid surfaces. It also warns against use on some plastic parts.
You can read more at
Oatey’s plumber’s putty guide.
When You Should Not Use Putty
Do not use regular putty on acrylic, ABS, or some plastic drains.
It can damage some materials over time. Use the product directions as the final guide.
For acrylic tubs or showers, Oatey recommends 100% silicone instead.
You can see more in
Oatey’s drain installation FAQ.
What To Do After Cleaning
Clean off all old putty first. The surface should be smooth and dry.
Inspect the rubber grommet closely. Replace it if it is cracked, flat, hard, or torn.
Reinstall the drain with the gasket in the correct spot. Tighten it evenly.
Do not overtighten the nut. Overtightening can deform the rubber seal.
After assembly, run water for several minutes. Then dry the area and check for drips.
Fill the sink or tub if possible. Then drain it while watching below.
If it leaks, take it apart again. Check the gasket position and drain alignment.
Simple Rule
If the drain came with a rubber grommet, use the grommet first.
Use plumber’s putty only when the instructions call for it.
When in doubt, silicone may be safer on plastic, acrylic, or fiberglass parts.
I’m Chris Mayer, writing for Plumbing 101.
