Lev 15:16-18

16If a man has an emission of semen, he shall bathe his whole body in water, and be unclean until the evening.17Everything made of cloth or of skin on which the semen falls shall be washed with water, and be unclean until the evening.18If a man lies with a woman and has an emission of semen, both of them shall bathe in water, and be unclean until the evening.