This is a permanent statute for the people: The one who sprinkles the water of purification must wash his clothes, and whoever touches the water of purification will be unclean until evening.

Exodus 27:21
In the Tent of Meeting, outside the veil that is in front of the Testimony, Aaron and his sons are to tend the lamps before the LORD from evening until morning. This is to be a permanent statute for the Israelites for the generations to come.

Numbers 19:7
Then the priest must wash his clothes and bathe his body in water; after that he may enter the camp, but he will be ceremonially unclean until evening.

And it shall be a perpetual statute to them, that he that sprinkles the water of separation shall wash his clothes; and he that touches the water of separation shall be unclean until even.