'Impurity' in the Bible
Then the priest will make her swear an oath, and he will say to the woman, "If a man has not slept with you, and if you have not had an impurity affair under your husband, go unpunished from the waters of bitterness that brings this curse.
“A man who is clean is to gather up the cow’s ashes and deposit them outside the camp in a ceremonially clean place. The ashes must be kept by the Israelite community for preparing the water to remove impurity; it is a sin offering.
That one shall purify himself from uncleanness with the water [made with the ashes of the burned heifer] on the third day and on the seventh day, and then he will be clean; but if he does not purify himself on the third day and on the seventh day, he will not be clean.
Anyone who touches a body of a person who has died, and does not purify himself, defiles the tabernacle of the Lord. That person will be cut off from Israel. He remains unclean because the water for impurity has not been sprinkled on him, and his uncleanness is still on him.
But a person who is unclean and does not purify himself, that person will be cut off from the assembly because he has defiled the sanctuary of the Lord. The water for impurity has not been sprinkled on him; he is unclean.
This is a permanent statute for them. The person who sprinkles the water for impurity is to wash his clothes, and whoever touches the water for impurity will be unclean until evening.