Another aspect of the halakhot of kitchenware items is the requirement to immerse them in a mikva (ritual bath). The halakha states that many types of kitchen items that were owned by a gentile, even if they were never used, must be immersed in a mikva in order for them to be permitted for use by a Jew. Obviously, a used implement that was in the possession of a gentile also requires kashering if one wants to use it. Even a new kitchenware item that was manufactured in a factory owned by a gentile, which does not need to be kashered, must be immersed in a mikva before using.

The halakha of immersion applies by Torah law to kitchen items made of metal. Earthenware and wooden products do not require immersion. Those made of glass do need immersion (by decree of the Sages). A blessing is recited over the immersion. Earthenware does not require immersion, but some have the practice to immerse ceramic dishes without a blessing, and one should consult his rabbi about this. Plastic does not require immersion, but there are those who immerse even plasticware without a blessing.

An item that requires immersion, whether new or used, must be brought to a mikva for immersion. Most ritual baths include a separate mikva for kitchenware only. This is the preferred situation for practical reasons, but is not absolutely necessary. It is permissible to immerse dishes and utensils in a mikva that is designated for people, but one should first consult the caretakers of the mikva. Using such a mikva for kitchen items requires great caution, since a broken piece of glass or a sharp utensil falling into the water is an obvious hazard for the people who come to immerse themselves in the mikva.

Before immersing an item of kitchenware, one recites the following blessing:

“Blessed are You, Lord our God, King of the universe, who sanctified us through His commandments, and commanded us concerning the immersion of a utensil.” If one is immersing more than one item, he concludes with the words “of utensils” in the plural.

Immediately after reciting the blessing, one should put the item briefly into the water, and while it is in the water, release his grip on it for a moment, so that the water completely touches it from all sides at once. Alternatively, he can pass it from one hand to the other while it is under the water.

Regarding kitchenware items that have an electric element which might be damaged if it is placed in water, it is advisable to consult a rabbi, as there are often solutions for such cases.