Numbers 19:20-21

20The person who is not clean might not wash himself and his clothes. If he does not do it, you must make that person separate from the people. That is because he has made the Lord's Holy Place become unclean. Because the priest did not splash special water on him he will not be clean.

21This rule is for now and for ever. The man who splashes the special water must also wash his clothes. Any person who touches the special water will not be clean until evening.