Watertight vs Impermeable - What's the difference?

As adjectives the difference between watertight and impermeable

is that watertight is so tightly made that water cannot enter or escape while impermeable is waterproof.

raincoat.

(en adjective)

So tightly made that water cannot enter or escape.

So devised or planned as to be impossible to defeat, evade or nullify.

a watertight''' contract; a '''watertight regulation.

* watertight alibi * watertightness

(en adjective)

impossible to permeate

not allowing passage, especially of liquids; waterproof

* sealed

* permeable