This Halacha is an excerpt from our Sefer
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Using Chametz vessels for cold Pesach foods:
One may remove a clean Chametz vessel from its closed area in order to use it for cold Pesach foods, whether the food is dry of liquidly. However, on Pesach, past the 6th hour of Erev Pesach, this is only allowed to be done on occasion and is forbidden to be done on steady basis. Before the 6th hour of Erev Pesach one may do so even on steady basis. At all times, prior to using the vessel, one must wash it well to verify it does not contain any visible Chametz.
Earthenware vessels: The custom is to avoid using Chametz earthenware vessels on Pesach for even cold Pesach foods, even on mere occasion. This applies even if the Chametz vessel was only used for cold Chametz foods; nevertheless the custom is not to use it on Pesach even for cold foods.
Knife: It is permitted on Pesach on occasion to use a clean Chametz knife to cut cold non-Charif Pesach foods, if one stabs the knife in the ground ten times prior to using it. Before the 6th hour of Erev Pesach, one may use it even on steady basis through cleaning it in the above method.
Using Chametz vessels for non-eating purposes:
It is permitted to use Chametz vessels on Pesach for non-food purposes, such as to heat up water for bathing and for laundry. [Thus, there is no need to purchase new Negel Vasser cups, basins, or garbage cans for Pesach. There is likewise no need to Kasher them, and they are simply to be well cleaned.]
 Admur 451:2; 450:13
 The reason: This is due to suspicion one may come to use it for hot foods on Pesach. [Admur ibid]
 From the letter of the law this is permitted if the vessels is washed, as explained above. However, the custom is to forbid it. [ibid]
 Admur 451:43
 Admur ibid; Michaber Y.D. 121:7
 Admur 450:13; See M”B 450:27
 See Piskeiy Teshuvos 450:9