- 1). Scrub the pumice stone under hot water. Run the water as hot as you can stand and apply firm pressure with a scrub brush. If you like, you can place a few drops of mild detergent on the stone while you are scrubbing. Continue to scrub until the water runs clear and there are no more soap suds.
- 2). Mix a cleaning solution of four cups water and one cup bleach in the pot and add your pumice stone. If this is not enough liquid to cover your pumice stone, then add more cleaning solution in the same 4:1 ratio.
- 3). Bring the bleach and water mixture to a boil. This will kill any bacteria in the interior of the stone and any crevices you may not have been able to reach with the brush. Allow the stone to boil for 10 minutes before removing the mixture from the heat.
- 4). Remove the pumice stone from the pot and allow it to dry. You can place it on a drying rack or towel. It is best to let it dry in direct sun if possible. Once the stone is completely dry it is ready for use once more.
Source...