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The actual sink: A sink needs to be Kashered. The Kashering of a sink is dependent on its material. A metal sink can be Kashered through Iruiy Keli Rishon. Most sinks, however, are made of porcelain or enamel which are non-Kasherable materials. Nevertheless, the custom is to do Iruiy Keli Rishon on even non-Kasherable material sinks. One then places a plastic sink insert into the sink which will be used throughout Pesach. [If one does not have a sink insert available, he is to cover the interior of the sink with tinfoil.]
The spout: The custom is to clean and wash the spouts of the sink, as throughout the year they have been used with hands that are dirty from Chametz. [One is to pour boiling water over the spout, and leave it open with the hot water running for a few moments.]
Knobs: One is to wash and clean the knobs of the faucet.
The drain: One should pour boiling water that contains bleach or Drano down the drain.
Metal strainer: The metal strainer which rests in the spout is to have Iruiy Keli Rishon performed on it.
Not to pour hot water in an unKashered sink on Pesach: One is initially to be careful not to use hot water that is over Yad Soledes [110° F] on Pesach, in a sink that is not Kasherable. This applies even if one has a sink insert. Thus, one should not turn on the hot water to the point of Yad Soledes and is likewise not to pour hot water into the sink so long as it is Yad Soledes, even if it is in a Keli Shelishi or Revi’i. [Accordingly, if one has a pot with hot water, he is to wait until it cools down prior to pouring it into a non-Kashered sink. One can mix cold water into the hot water in order to achieve this quicker.] If the water is warm, below Yad Soledes, it may be poured into the sink. Nonetheless, Bedieved, if one poured hot water into the sink, everything remains permitted, even it was very hot and was poured from a Keli Rishon.
 Piskeiy Teshuvos 451:11
 The reason: As it has likely absorbed Chametz through a) Pouring hot Chametz, or Chametz water into it [i.e. draining the pot of pasta]; b) Having Chametz soak in it for 24 hours. C) Washing Chametz dishes with Yad Soledes water. [See Admur 451:21 regarding the handle of a pot and the same should apply here as well; Admur 451:46 regarding a grinder] and we are initially stringent to follow minority usage. [Admur 451:27] Now, if it is not Kashered, we suspect that perhaps one will pour hot Pesach food into it [Nitzuk], or have Chametz vessels soak in it for 24 hours, or wash Pesach dishes with hot water, during Pesach and make everything prohibited according to our custom to prohibit the food even if the pot is not be Ben Yomo. [However, if its majority usage is with cold, then the food remains Kosher.]
 Admur 451:77 regarding the spouts of wine barrels
 Piskeiy Teshuvos ibid
 The reason: As the sink has absorbed Chametz, as stated above, and on Pesach we are initially stringent even regarding a Keli Sheiyni transfer and even if not Ben Yomo, and even if the Chametz absorption was only due to minority usage. [Admur 451:27 and 33; 72]
 See Admur 451:34
 As Bedieved we follow majority usage by a non-Ben Yomo Chametz vessel [Admur 451:27 and 31 and 72] and hence since the sink’s majority use is with cold products, it is therefore Kosher Bedieved.