Numbers 19:11

A man who is clean shall gather up the ashes of the heifer, and lay them up outside of the camp in a clean place; and it shall be kept for the congregation of the children of Israel for a water for impurity: it is a sin offering.

He who gathers the ashes of the heifer shall wash his clothes, and be unclean until the evening: and it shall be to the children of Israel, and to the stranger who lives as a foreigner among them, for a statute forever.

the same shall purify himself with water on the third day, and on the seventh day he shall be clean: but if he doesn't purify himself the third day, then the seventh day he shall not be clean.

Whoever touches a dead person, the body of a man who has died, and doesn't purify himself, defiles the tabernacle of Yahweh; and that soul shall be cut off from Israel: because the water for impurity was not sprinkled on him, he shall be unclean; his uncleanness is yet on him.