Plumber's putty is a type of putty used as a sealant in plumbing. It is a pliable substance used to make watertight seals around faucets and drains. The putty is a basic component of a plumber's toolkit and is often used when replacing plumbing fixtures. Plumber's putty formulations vary but commonly include powdered clay and linseed oil. Other formulas use limestone, talc, or fish oil. RTV silicone or epoxy sealants may be used in place of putty.
A different material also used to make threaded joints watertight is thread seal tape.