Leach & Leech

Leach means to remove a chemical, a metal, etc. from a substance by the action of a liquid passing through the substance: “Lemon can leach certain stains from clothes if rubbed on them.”
Leech, on the other hand, has the following meanings:-
1. Any of several blood sucking worms; to use a blood sucking worm for medicinal purposes: “In ancient times, the doctors used leech to suck the blood of the ailing person in order to treat him.”