Numbers 19:7-8
19:7 Then the priest must wash his clothes and bathe himself in water, and afterward he may come into the camp, but the priest will be ceremonially unclean until evening.
19:8 The one who burns it must wash his clothes in water and bathe himself in water. He will be ceremonially unclean until evening.
Numbers 19:10
19:10 The one who gathers the ashes of the heifer must wash his clothes and be ceremonially unclean until evening. This will be a permanent ordinance both for the Israelites and the resident foreigner who lives among them.