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How do I kasher a dishwasher?

by Rabbi Dovid Bendory, 23 Sivan 5765 (June 30, 2005)

OK, so you need to kasher a dishwasher. How do you do it?

For those who hold that a dishwasher can be kashered, I recommend the following kashering procedure. This kashers the dishwasher by internal hagala — similar to boiling water in a pot:

  1. Remove the racks. Inspect the racks, the inside of the dishwasher, and especially around the drain filter for any pieces of food. Be especially careful to remove the filter, clean in and around it, and to check inside under it to be sure there is no food. Return the racks to the dishwasher. You must do this even if you are 100% sure there is no food in the dishwasher.
  2. Let the dishwasher sit unused for 24 hours.
  3. Run the empty dishwasher through a full cycle with soap on the highest temperature setting.
  4. Put two large stones in the oven on the highest temperature for at least one hour. (I use bricks.) The temperature should be at least 500 oF, but use a higher setting if you have one. (This will likely smell a bit as the moisture is cooked out of the rocks. Sorry.)
  5. Once the rocks are heated in the oven, put one on each rack of the dishwasher. Be VERY careful. If you drop one of these rocks, depending on your floor, you will have permanent damage. The rocks are hot enough to melt the plastic racks on contact and will cause serious burns if you touch them by accident. The way I handle the rocks is as follows:
    1. Prior to putting the rocks into the oven, I put pieces of wood onto the plastic racks in the dishwasher and practice placing the cold rocks onto them. In addition, I make sure the rack will slide in and out easily with the rocks in place.
    2. I put the rocks into the oven on small aluminum tins. When the rocks are fully heated, I carry them to the dishwasher by lifting the tins. I practice carrying them over to the dishwasher on the tins and putting them onto the wood.
    3. Finally, I punch lots of holes in the tins so that water fill flow through.
  6. Close the dishwasher and run it through a full cycle on the highest temperature setting with soap. Because of the hot rocks, the water inside will boil. Don't be surprised if you get steam seeping out of the dishwasher.
  7. At the end of the cycle, open the dishwasher, pull the racks out and let everything sit and cool for an hour or so. Don't touch the rocks — they will still be hot.
  8. After the rocks have cooled and you can safely remove them, you're finished. You now have a kosher dishwasher.

Before following this procedure it is essential that you check with your communal rav with regard to the dishwasher, as some hold that a dishwasher cannot be kashered at all.

References: See Hagalas Keilim 13:225-228.

Questions to ponder:

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