'Impurity' in the Bible

Now a man who is [ceremonially] clean shall collect the ashes of the heifer and deposit them outside the camp in a clean place, and the congregation of the Israelites shall keep it for water to remove impurity; it is [to be used for] purification from sin.

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.

Whoever touches a corpse, the body of anyone who has died, and does not purify himself, defiles the tabernacle of the Lord; and that person shall be cut off from Israel [that is, excluded from the atonement made for them]. Because the water for impurity was not sprinkled on him, he shall be unclean; his uncleanness is still on him.

So it shall be a perpetual statute to them. He who sprinkles the water for impurity [on another] shall wash his clothes, and he who touches the water for impurity shall be unclean until evening.

everything that can stand fire, you shall pass through fire, and it shall be clean. Nevertheless, it shall also be purified with the water of purification [to remove its impurity]; and all that cannot stand fire [such as fabrics] you shall pass through water.