The man who is ceremonially clean is to sprinkle the unclean person on the third day and on the seventh day. After he purifies the unclean person on the seventh day, the one being cleansed must wash his clothes and bathe in water, and that evening he will be clean.
Jewish Publication Society of America Version (JPS1917) - Numbers 19:19 >And the clean person shall sprinkle upon the unclean on the third day, and on the seventh day; and on the seventh day he shall purify him; and he shall wash his clothes, and bathe himself in water, and shall be clean at even.