Moses sprinkling water on them was symbolic of their atonement. AT: "Sprinkle on their the water that symbolizes atonement" (See: [[rc://en/ta/man/translate/translate-symaction]])
# wash their clothes
The Levites are supposed to wash their own clothes. You can make clear the understood information. AT: "then make them wash their clothes" (See: [[rc://en/ta/man/translate/figs-ellipsis]])
# a young bull and its grain offering
When offering a young bull, a grain offering was usually required to accompany it.