Halachic guidelines compiled by Rabbi Yaron Ashkenazi, spiritual supervisor at the Kav HaHalacha hotline

Any utensil you use during the year may have absorbed the taste of chametz. If you want to use it on Pesach, you need to kosher it properly. The method of kashering follows its most common use. So, for glasses used only with cold, you can use them on Pesach after a good cold-water wash. But utensils used with heat require hag'alah (immersion in boiling water). This practice appears in the Torah (Numbers 31:23) in the section about the utensils of Midian: "Anything that comes into fire you shall pass through fire and it will be purified... and anything that does not come into fire you shall pass through water." And in the Gemara (Pesachim 74) we’re given the rule for kashering utensils: "As it absorbs, so it expels." So when kashering the kitchen, we look at how each item is used—and we kasher it accordingly.

Here are the types of utensils and how to kosher them:

Oven

Since an oven usually doesn’t absorb directly from chametz but from the steam rising off food—though crumbs do sometimes fall on the oven itself while baking—you can kosher it for Pesach as follows: wait 24 hours after the last bake, then clean the entire interior thoroughly, and run it on a high setting for an hour or more. Baking trays, however, cannot be kashered this way because they absorb directly from chametz and would require libun chamur (intense heating). Since you can’t practically do libun chamur on them, replace the trays.

About a pyrolytic oven (self-clean cycle at very high heat, above 500°C): you may run the cycle with the trays inside; afterward, wipe the oven and trays, and everything is kosher for Pesach.

Stovetop

The cooktop surface should be cleaned well and covered with heavy-duty aluminum foil. There’s no need to pour boiling water on it—just cover with thick foil. You do not need to open the top to reach the internal area beneath the burners with the wires, etc. Since hands don’t reach there, the pre-holiday nullification (bitul) done after the bedikat chametz and on Erev Pesach is sufficient for any crumbs in such inaccessible places.

The grates should be kashered with standard hag'alah. If they were kashered this way, there’s no need to cover them with foil. Alternatively, you may pour boiling water over them and then cover with foil (in this case, thinner foil that hugs the shape is better). Make sure the foil layer is sturdy enough not to tear during Pesach. If it tears mid-holiday, replace the covering.

The burners don’t need hag'alah; a good wash is enough, since they’re constantly exposed to direct flame and don’t absorb in a way that requires kashering.

Ceramic (Halogen) Cooktops

Ceramic cooktops are considered like glass and need only to be washed. One who is strict and runs them on empty is praiseworthy. (Responsa Ma'aseh Choshev, vol. 6, siman 10).

Hag'alah (Kashering by Boiling) – General Rules

Before the how-to of kashering each utensil, here are essential rules for hag'alah:

1. Clean the utensil thoroughly so it’s completely free of residue. Sometimes heavy use leaves stuck-on spots (black or brown specks) that can’t be removed. In that case, you cannot kosher the utensil; it must be perfectly clean.
2. Parts attached to the utensil—like pot handles, lid handles, etc.—do not need to be removed; they’re considered part of the same utensil. Still, clean well around screws and check there’s no chametz residue or rust.
3. If you’re kashering dairy and meat utensils together, add a taste-neutralizing agent (like dish soap) to the boiling water before immersing the utensils.
4. Order of operations: Wait until the water is at a rolling boil, then immerse the utensil and keep it in until the water returns to a rolling boil (a few seconds).
5. Remove the utensil and rinse it in cold water.
6. These guidelines are for those who cannot access a communal kashering station and need to do it at home. Since there are many details in hag'alah, it’s best, when possible, to use a supervised kashering site rather than doing it yourself.

Pots and Pans

Because they absorb through frying or cooking—i.e., through liquid—their kashering is by immersion in boiling water (hag'alah). Ideally, don’t rely on DIY home kashering since many details matter. If there’s no kashering site near you, you can consult the new halachic hotline of "Hidabroot" in partnership with the Kav HaHalacha organization for instructions on doing it at home.

Glass Pot or Baking Dish

All glass utensils are kashered by washing, even if used as a kli rishon (a first vessel) on the fire, because glass does not absorb. So all glassware can be prepared for Pesach with a thorough wash, even items used for cooking and baking; no hag'alah is required, provided the item is completely clean with no stuck-on residue. If there are black or brown specks that won’t come off, do not use that item on Pesach. Many Ashkenazim are stringent not to kasher glass at all and instead buy new glassware for Pesach.

Teflon (Nonstick) Pan

A Teflon pan can be kashered with hag'alah because the nonstick coating is considered plastic, and Maran Rav Ovadia Yosef held that plastic can be kashered by hag'alah. Year-round, if you want to switch a pan from meat to dairy or vice versa, you can kasher it with hag'alah. However, a pan that absorbed other prohibitions requires libun until sparks fly from it.

Grill Pan, Plancha, Grill, Liver Grate, etc.

Anything used for dry grilling without liquid requires libun with a torch until the utensil glows and sparks fly. Modern cookware is delicate and may be damaged, and people often underdo the process. Therefore, it’s best to replace these items before Pesach. A grill pan (plancha) should not be kashered for Pesach; buy a new one. A gas grill that can reach over 400°C can be kashered: clean the grill and grate well, then run it on its highest heat for about 30 minutes. Even so, it’s advisable to replace the grate for Pesach. A grate designated only for liver, since it’s used exclusively for liver and not with chametz in heat, may be used for liver on Pesach without kashering.

Flatware, Plates, and Cups

Material matters: Metal utensils require kashering and can be kashered. Glass does not absorb and needs only washing. Earthenware does not have a kashering process (as explained in the Gemara). Flatware (made of metal) typically absorbs from hot liquid in a kli sheni (second vessel)—for example, when hot water is poured from an electric kettle (kli rishon) into a plate with the flatware (kli sheni). You can kasher flatware by pouring boiling water over it. Plates: if made of earthenware or porcelain, they cannot be kashered. If plastic, you can pour boiling water over them. If glass, washing suffices. The same applies to cups: earthenware has no kashering; glass requires only washing.

Countertops

Many modern countertops are engineered stone (stones bonded with resin), and manufacturers warn against placing hot pots directly on the surface. Typically, matching hot pads (small movable slabs) are provided for hot pots. Therefore, the countertop itself doesn’t require kashering—washing is enough. In fact, pouring boiling water on it can crack it. Even if a hot pot was placed on the counter once, washing suffices since its usual use is cold; no covering is needed. For the small matching hot pads used for hot pots, pour boiling water over them or cover them with heavy-duty foil. The same applies to older-style stone counters used directly for hot pots: kasher by pouring boiling water, or cover with heavy-duty foil.

Sinks and Ceramic Tile

During the year, people often pour hot water with chametz into the sink—for example, draining cooked noodles into a colander in the sink. Therefore, kosher the sink by pouring boiling water from a kli rishon (a pot from the stove or an electric kettle). It’s proper to be stringent and pour boiling water three times, because sinks often include ceramic components and there are stricter views about ceramic. Hence, three pours are recommended.

The kitchen's ceramic tile doesn’t require hag'alah, even if hot splashes sometimes reach it or a hot pot brushes it. Its typical use is cold, so washing with water and soap is enough.

Kitchen Faucet and Strainer

The faucet needs only washing. Even though steam can rise from the sink toward the faucet, it doesn’t absorb in a way that requires kashering since that steam isn’t truly boiling. Sometimes there’s rust or grime where the faucet meets the ceramic. That’s not chametz, and technically it doesn’t need cleaning, though it’s good to tidy it. Faucet handles should be washed well with water and soap; no kashering needed.

Also clean the sink strainer, and it’s good to pour boiling water from a kli rishon over it.

Order of kashering: Before pouring boiling water in the sink, dry it thoroughly. Start from the drain area at the bottom, then move up to the sink walls and the countertop (if you’re kashering the counter).

Refrigerator and Freezer

Washing is sufficient. You don’t need to open hollow plastic parts in the freezer, etc., since they’re inaccessible to hands, and any crumbs there wouldn’t add up to a kezayit. The nullification (bitul) after the bedikat chametz and the biur chametz on Erev Pesach covers that.

Kitchen Cabinets

A thorough cleaning is enough; there’s no need to line the shelves.

Electric Kettle

Since it’s used only to boil water and not with chametz, a good rinse with cold water suffices. However, citric acid is produced from chametz; if you used citric acid in the kettle to remove scale, do hag'alah: fill the kettle to the brim with water and boil until the water overflows out of it.

Shabbat Urn

If the urn is used only to heat water and nothing is warmed on top, rinsing with cold water is enough. If citric acid was used, kasher it like the electric kettle above. Note one more point with a Shabbat urn: people sometimes warm bread or bourekas on top. If the top lid has holes, crumbs may have fallen into the urn and become stuck within layers of scale. Even if you later descale, scale is never fully removed, and we’re concerned a crumb remains in some corner—so that urn has no kashering option. If the top lid has no holes, you can do hag'alah: fill the urn itself with water to the top and boil, and kasher the lid in the regular way.

Sandwich Toaster

Requires libun chamur. Since that’s not feasible, it cannot be kashered; buy a new one for Pesach.

Toaster Oven

Kasher like a regular oven: clean thoroughly with a cleaning agent, then run on the highest heat for one hour. Trays, however, can only be kashered with libun chamur until sparks fly.

Blender (Magimix) and Meat Grinder

If you didn’t grind chametz together with something pungent (charif), washing suffices. If you did grind chametz with a pungent ingredient, or you ground hot chametz, kasher with hag'alah (boiling water).

Microwave

Clean the microwave thoroughly, place a cup of water with a bit of soap inside, and run it until the water boils and steam reaches all corners and vents. That kasheres it for Pesach.

Dishwasher

A dishwasher first rinses with cold water, then adds detergent, then sprays hot water. To kasher: clean the machine completely so no food residue remains in the unit or on the racks, then run it empty with detergent on a hot cycle.

Hand Whisk, Mixer, Filtered-Water Devices, etc.

These are generally used cold, so washing is enough. If a hand whisk is used to mix flour, it has no kashering option, since flour crumbs may enter the device’s ventilation openings and can’t be reached. A stand mixer that’s fully sealed with air vents located completely away from the bowl can be kashered by washing, and its plastic bowls can also be kashered by washing (of course, when these bowls are used cold).

Filtered-water machines: even if they dispense hot water, they have no contact with chametz. An exterior wipe-down is enough, and they’re kosher for Pesach.

Espresso Machine

Because some capsules may contain a mixture involving chametz, kasher all brew-path components and the milk frother with hag'alah. The rest of the unit can be kashered by washing.

Click here to download these guidelines as a PDF.