Waiting 24 Hours Before Kashering
One must wait twenty-four hours after a utensil has become treif before it can be kashered through hag'alah (using boiling water); additionally, the utensil has to be completely clean. Alternatively, a utensil can be kashered within twenty-four hours provided that the kashering pot contains shishim (sixty times more water than the volume of the utensil bring kashered). However, it is customary to always wait twenty-four hours before kashering, even if the kashering pot contains shishim. Kashering utensils at a public kashering station raises the following issues: it is difficult to ascertain whether other people kashering their utensils in the same kashering pot have indeed waited twenty-four hours after their item has become treif (non-kosher), and whether the water contains shishim. To circumvent these problems, and to avoid impacting the kashrus of the other utensils being kashered at the same time, bleach or a similar liquid—which alters the water’s taste—should be added to the water. Nevertheless, lechatchilah (preferably), one should use pure boiling water for kashering, and not water with another liquid added.
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