Numbers 19:17-21
And for an unclean person they shall take of the ashes of the burnt heifer of purification for sin, and running water shall be put thereto in a vessel:
Nave's Topical Index—AKJV

Numbers 31:23
Every thing that may abide the fire, you shall make it go through the fire, and it shall be clean: nevertheless it shall be purified with the water of separation: and all that stays not the fire you shall make go through the water.
Nave's Topical Index—AKJV