What is plumber’s putty used for?

Plumber’s putty is a soft, moldable sealant used to create watertight seals around sinks, drains, and other low-pressure plumbing fixtures. It’s easy to work with and long-lasting, but it’s not safe for every surface or every type of plumbing job.

TL;DR

• Plumber’s putty creates watertight seals for sinks, drains, and low-pressure fittings.
• It should not be used on granite, marble, plastics, or other porous surfaces.
• It is not designed to withstand water pressure inside pipes.
• For toilets, leave a small gap unsealed so leaks can be detected early.
• Always check manufacturer labels to ensure compatibility with your countertop or fixture.

Sinks

You can use plumber’s putty around the rim of a sink to form a watertight barrier, but avoid using it on granite, marble, or other porous stone countertops. It is compatible with laminate surfaces such as Formica.

To create a proper seal during a sink installation, apply the putty to the underside of the sink rim and press the sink firmly into place. Some sinks include mounting clips that apply consistent pressure, helping the putty seal evenly and preventing water from leaking below the countertop.

Drains

Plumber’s putty is commonly used to seal sink or bathtub drains. Place a bead of putty under the drain flange, then tighten the drain to compress the putty and create a watertight seal.

Toilets

Plumber’s putty can be used to seal the toilet base to the floor, but use caution. If you seal the base completely and a leak develops, water can become trapped and damage the subfloor without visible warning. Leave a small section unsealed so any leak becomes noticeable early.

Pipes and Plumbing

Plumber’s putty is not designed to withstand internal water pressure and should not be used on pressurized pipes. On low-pressure threaded fittings, it may be used to help create a seal by applying putty to the threads before tightening. Wipe away any excess and allow time for the putty to set.

Always check product labels, as plumber’s putty contains oils that can discolor or damage some materials. Some manufacturers produce specialized formulas that are compatible with surfaces like stone or certain plastics.