Water key

A water key is a valve or tap used to allow the drainage of accumulated fluid, consisting mostly of saliva but partially of breath moisture, from musical instruments such as trombones or trumpets. It is otherwise known as a water valve or, less euphemistically, a spit valve. In valved instruments, they are found always on the main tuning slide, and sometimes on valve slides. On the trombone, it is on the downwind side of the bend in the hand slide. Baritone saxophones have a water key at the bottom of the loop at the top of the instrument.