Leviticus 15:16-18

And if any man's seed of copulation go out from him, then he shall wash all his flesh in water, and be unclean until the even. And every garment, and every skin, whereon is the seed of copulation, shall be washed with water, and be unclean until the even. The woman also with whom man shall lie with seed of copulation, they shall both bathe themselves in water, and be unclean until the even.