Numbers 19:11

And a man [that is] clean shall gather up the ashes of the heifer, and lay [them] up without the camp in a clean place, and it shall be kept for the congregation of the children of Israel for a water of separation: it [is] a purification for sin.

And he that gathereth the ashes of the heifer shall wash his clothes, and be unclean until the even: and it shall be unto the children of Israel, and unto the stranger that sojourneth among them, for a statute for ever.

He shall purify himself with it on the third day, and on the seventh day he shall be clean: but if he purify not himself the third day, then the seventh day he shall not be clean.

Whosoever toucheth the dead body of any man that is dead, and purifieth not himself, defileth the tabernacle of the LORD; and that soul shall be cut off from Israel: because the water of separation was not sprinkled upon him, he shall be unclean; his uncleanness [is] yet upon him.