A clean man gathers the gray dust from the fire. He puts it in a clean place outside the camp. The gray dust is kept to make water that makes people clean. ⚫️➡️️
Then a man who is ceremonially clean is to gather up the ashes of the heifer and store them in a ceremonially clean place outside the camp. They must be kept by the congregation of Israel for preparing the water of purification; this is for purification from sin.
KJV
And a man [that is] clean shall gather up the ashes of the heifer, and lay [them] up without the camp in a clean place, and it shall be kept for the congregation of the children of Israel for a water of separation: it [is] a purification for sin.
ASV
And a man that is clean shall gather up the ashes of the heifer, and lay them up without the camp in a clean place; and it shall be kept for the congregation of the children of Israel for a water for impurity: it is a sin-offering.