Short definition
Plumber’s putty is a soft, non-hardening, clay-like sealant rolled into a thin rope and bedded under sink-drain flanges, faucet bases, and pop-up drain assemblies. It seals against seepage and stays workable indefinitely. Don’t use it on plastic fixtures, stone counters, or pressurized supply joints — wrong product.
What it is
A blend of clay, fish oil, and other oils with the consistency of fresh modeling clay. You knead a ball, roll a rope about a quarter-inch thick, lay it under whatever flange or base needs sealing, and tighten the fixture down. The putty squishes into the gap, and excess gets wiped away.
Unlike silicone caulk, plumber’s putty doesn’t cure or harden — it stays flexible forever, which makes it easy to remove later. Unlike thread sealants, it isn’t rated for pressurized joints; use only where a fixture rests on a surface and water might seep around the perimeter.
Standard brands — Oatey, Hercules, Harvey, Danco — all stock current 2026 product. Stain-free formulations exist specifically for stone counters and white plastics.
Why it matters to a homeowner
If you’ve installed a kitchen basket strainer or a bathroom-sink pop-up drain, you’ve used (or should have used) plumber’s putty. It’s cheap, simple, and forgiving — apply too much and the excess just squeezes out for cleanup.
The trap is using it where you shouldn’t. Plumber’s putty on a plastic flange leaches oils that discolor the plastic. On natural stone (granite, marble, soapstone), the oils stain the stone permanently — use stain-free putty or silicone caulk instead. On a faucet swivel joint or any pressurized water-supply fitting, putty fails because it can’t bond — those joints need silicone, thread sealant, or a proper compression seal.
WA toilet-base sealing is a separate question — most jurisdictions require silicone caulk at the toilet base, not putty. We cover that in the toilet entry.
Common failure modes
- Used under a plastic flange. Oil leaching discolors the plastic; the seal still works but the fixture looks bad.
- Used on stone. Oil stain in the counter that doesn’t come out.
- Rolled too thin. Gaps left in the seal; perimeter leaks.
- Used on a moving or pressurized joint. Fails immediately. Wrong product.
Common variants
- Plumber’s putty (this entry). Non-hardening, non-pressurized fixture seating.
- Stain-free plumber’s putty. Reformulated for stone and white plastics; slightly pricier.
- Silicone caulk. Pressure-tolerant adhesive sealant; stays flexible; harder to remove. Use for tubs, tile, toilet bases.
- Plumber’s tape (PTFE thread tape). For threaded supply joints.
- Pipe dope. Thread-sealant compound; alternative to PTFE tape.