The Levites also purified themselves from sin and washed their clothes. Aaron presented them as a wave offering before Adonai, and, he made atonement for them to purify them.
He is to purify himself on the third day and on the seventh day. Then he will be clean. But if he does not purify himself on the third and seventh days, he will not be clean.
The clean person will sprinkle the unclean one on the third and seventh days. He is to purify himself on the seventh day, and on the seventh day he is to wash his clothes and bathe himself in water, and at evening he will be clean.
So Moses, Aaron and the entire community of Bnei-Yisrael did so with the Levites. All that Adonai had commanded Moses regarding the Levites, so Bnei-Yisrael did to them.
After that, the Levites came to do their tasks before Aaron and his sons in the Tent of Meeting, just as Adonai had commanded Moses concerning the Levites.
This is what you must do to them to make them clean: Sprinkle the purifying water on them, then have them shave their whole bodies and wash their clothes, thus purifying themselves.