The status of Pareve foods cooked in a meat pot or vice versa:
If a Pareve food was cooked in a meat or dairy pot [or was cut with a meat or dairy knife while the Pareve food was hot] then the law regarding whether the food remains Pareve, and one may eat the Pareve food with the opposite type of food that the pot [or knife] belonged to, is dependent on the following factors:
- Was the Pareve food a Davar Charif or does it contain a Davar Charif?
- Was the pot [or knife] clean from residue of meat/milk?
- Is the pot [or knife] Ben Yomo?
Pareve food is Charif: If a Pareve Charif/sharp food was cooked in a meat pot then even if the pot was clean and not Ben Yomo, the food becomes meaty and is forbidden to be eaten with milk. Bedieved, if one cooked this sharp food with dairy, one requires 60x in the dairy food versus the sharp food in order for the dish to be Kosher.
Pot contains meat/dairy residue: If the meat pot contained meat residue [i.e. fat and oil] upon the non-Charif Pareve food being cooked in it, then the Pareve food is meaty and may not be eaten with milk. If, however, the Pareve food contains 60x versus the meat residue and the pot was not Ben Yomo, then the food remains Pareve. [In general, we assume that the Pareve food in the pot contains 60x versus the fat residue unless one knows for certain that it does not. However, if one only cooked a small amount of Pareve in the pot, then we assume it does not contain 60x, unless one knows for certain that it does.]
Pot is clean not Ben Yomo: If a Pareve non-Charif food was cooked in a clean non-Ben Yomo meat pot then the custom even according to the Rama, is to allow eating the Pareve food together with milk products even initially. [Regarding if this may be even initially be done, see Q&A!]
Pot is clean Ben Yomo: Coming up in part 2!
If one cooked Pareve food in a dairy pot then if one cooked a Davar Charif in the pot [in a way that is defined as a Davar Charif as explained above], such as onions or garlic, or the pot was dirty with dairy residue, then it is forbidden to eat the food together with meat. If the pot is clean, not Ben Yomo and does not include a Davar Charif, one may eat it together with meat.
May one even initially cook Pareve food in a non-Ben Yomo meat pot with intent to eat it with the opposite food?
Some Poskim rule it is forbidden to initially cook Pareve food in a non-Ben Yomo meat pot with intent to eat the food with milk products, or vice versa. Other, Poskim, however, rule that it is permitted to do so even initially with intent to eat with the opposite food. Practically, Sefaradim may be lenient even initially, and Ashkenazim may be lenient in a time of need, such as if there is no other pot available. According to all, if one already cooked the Pareve food in a non-Ben Yomo meat pot with intent to eat with milk, he may eat it with milk.
May one cook Pareve in a non-Ben Yomo meat pot in order to eat with dairy if he has no other pots available?
Yes, as explained above.
Having a special water pot:
Some are particular to have a special Pareve water pot for the sake of heating up water that will be used with other foods, and they do not heat up the water in a meat or dairy pot.
 Chavas Daas 95:5; Pischeiy Teshuvah 95:4; Kaf Hachaim 95:23
 Rama 95:2; Implication of Aruch 24; Rashba 449; See also Michaber 103:6
Other opinions & Ruling of Michaber: Some Poskim rule that according to the Michaber [mentioned in 96:1 regarding a knife which cut a Davar Charif that if it was not Ben Yomo it remains Pareve according to the first opinion then] if the pot was clean and not Ben Yomo, Bedieved if it was cooked with the opposite food it does not require nullification. [Hakashrus 10:113; See Kaf Hachaim 96:11] Other Poskim argue on the Rama’s conclusion based on Rashba and Aruch ibid and suggest that even according to the Rashba and Aruch who rule regarding a knife that Charif turns non-Ben Yomo into Ben Yomo, by a pot the rule is different and Charif does not make non-Ben Yomo into Ben Yomo. The reason is because the concept of Nat Bar Nat still applies even by Charif, and hence only when there are two Nats, such as by a knife, do we say the taste is Beiyn, however when there are three Nats, such as the case in the case of a pot, then it is permitted. Practically, this opinion concludes that by definite Charif one is to be stringent like the Rama while by questionable Charif one may be lenient. [Makom Shmuel 89, brought in Pischeiy Teshuvah 95:4]
Is the concept of a Davar Charif a Biblical or Rabbinical concept? See Chapter 96 Halacha ??
 The reason: As the sharp food enriches the meaty taste of the pot and effects that its taste be considered Beiyn [direct taste from meat] and is thus no longer considered Nat Bar Nat. [Shach 95:7]
 Michaber 95:1
 This follows the ruling of Rama 95:2, however according to the Michaber, the food remains Pareve even if the pot was was Ben Yomo, as explained next.
 Issur Viheter 33:2; Minchas Yaakov 57:11; P”M 95 S.D. 1; Zivcheiy Tzedek 95:11; Kaf Hachaim 95:13
Other opinions: Some Poskim rule that we do not assume the food contains 60x the residue, unless one knows for certain. [Peri Toar 95:3]
 Zivcheiy Tzedek 95:11; Kaf Hachaim 95:14
 Rama 95:2
Other opinions: Some Poskim rule that initially one may not eat Pareve foods cooked in a non-Ben Yomo meat vessel together with milk. [Rashal Issur Viheter Shelo on Shaareiy Dura; Yam Shel Shlomo Kol Habsar 63, brought in Taz 95:4]
 The reason: The reason for this is because the taste of the pot is considered spoiled and is Nat Bar Nat and thus we are lenient even initially.
 Hakashrus 10:94
 Devar Moshe Y.D. 9; Chochmas Adam 48:2
 Beis David Y.D. 42; Zivcheiy Tzedek 95:4; Kaf Hachaim 95:3
 The reason: As in such a case we have two reasons for leniency; 1) The pot is not Ben Yomo 2) The meat taste is Nat Bar Nat. [Kaf Hachaim ibid]
 Zivcheiy Tzedek ibid; Kaf Hachaim ibid
 Chochmas Adam ibid; See Rama 89:3 and Shach there; Hakashrus 10:95
 Peri Chadash 95:1; Lechem Hapanim 95:3; Kreisi 95:1; Kehilas Yehuda 95:1; Zivcheiy Tzedek 95:5; Kaf Hachaim 95:5
 Chochmas Adam 48:1
 See Shulchan Gavoa 1; Kaf Hachaim 95:4