Lo Basi Ella L’orer: Being Pogem Water

A common way to heat products is through the use of a water loop. Steam from a boiler is used to heat water which then cycles through a loop and in turn heats products. This same water loop can be used to heat multiple products either simultaneously or one after the next. The water which heats the non-kosher products will become non-kosher based on the halacha of “tipas chalav shenafal al hakdairah mibachutz” (Y.D. 92:5). Even a dedicated kosher kettle will become non-kosher if it is heated with “tainted” water.

There are basically two approaches to resolving this problem. One is to drain the water loop and the other is to be pogem the water.

If one plans on draining the water and kashering the kettles, the draining should be done 24 hours before the kashering. Recently we had a situation where although the Mashgiach instructed the company to drain the water loops and kettle jackets, these instructions were ignored and only came to light after the huge kettle was on its way to being boiled. The kettle, loop and jacket were subsequently drained and idled for 24 hours and a second kashering performed. It is worthwhile when to talking to companies to stress the importance of following every detail of the kashering protocol.

In some cases the company cannot wait 24 hours, and we allow for being pogem the water in the jacket or water loops. What level of pegima is necessary? Is it enough if the water is pagum (tastes bad) or must it be nifsal mai’achilas adam?

The Shulchan Aruch (Y.D. 95:4) says that if ashes were added to a pot of water and then milchig and fleishig dishes were added the dishes remain kosher since the ta’am of meat will mix with the ashes and will impart a ta’am lifgam. The Pri To’ar (Y.D. 95:6) crystallizes this point by commenting, if issur was cooked in a pot with ashes, the issur would remain forbidden. However, the ta’am that emanates from the issur would not assur the kli since it is ta’am lifgam. We see clearly that although the issur does not reach the level of nifsal mei’achilas adam and as such the piece of issur remains assur, nevertheless it cannot assur since what is absorbed will be a ta’am lifgam. Based on these sources, Rav Belsky has said that it is enough if the water tastes bad. However, the Chazon Ish (Y.D. 23:1) seems to require enough ash to make the water nifsal mai’achilas adam. Rav Schachter recommended that whenever possible we should require enough pegima to make the water pagum ligamrei.1

Which chemicals are effective as a pogem?

The best pogmim are items that have no food application such as Bitrix (3-5 ppm), caustic soda2 (1-2%) and boiler chemicals. Propylene glycol at 15% concentration is completely nifsal mai’achilas adam, however at much lower percentages it is added to foods. The concern is that perhaps only a small amount of the ta’am of propylene glycol will transfer and actually give a good taste into the food, Still Rav Schachter has said that this is acceptable; since in its current state it is nifsal.

Boilers present an additional challenge because many pogmim do not travel with the steam but simply remain behind in the boiler. Even if one is properly pogem the boiler, the steam and subsequent condensation might not taste pagum. Is this acceptable? Rav Belsky has said that if the boiler water was originally nifsal ligamrei then it is acceptable. One of the reasons for this is leniency is since “nifsal mai’achilas adam” water has a chezkas kashrus, we can assume it remains kosher unless we know otherwise. Therefore, even if much of the davar hapogem is removed through distillation, we can assume that ta’am issur (if there was any) was removed as well.3

Te’ima (tasting without swallowing) of issur is forbidden mi’dirabanan.4 If so, how is one permitted to taste boiler water to make sure that they are sufficiently pagum?

Tzemach Tzedek (siman 47) permitted those who make soap to be to’em the soap, to see if it needs more salt, since te’ima is dirabanan and soap is pagum.

The Mateh Yehonasan (Y.D. 108:5) explains that te’ima is only forbidden in situations where there is a concern that one might come to swallow the issur, however if the issur is pagum and this concern does not exist (as in the case of soap) then te’ima is permitted. Boilers usually contain hazardous chemical treatments and davarim marrim. Since one would definitely be careful not to swallow this water the issur would not apply.

Another reason to allow tasting boiler water is based on Taz (98:2), who indicates that whenever the issur is only a safek, te’ima is permitted.5

In summary:

  • 24 hours before kashering, water loops and jackets should be drained
  • If one is pogem water, it should taste bad. Lechatchila it should be nifsal mai’achilas adam
  • When one is pogem a boiler, if there is concern that the pogem is distilled from the steam, it is necessary that the boiler be pagum ligamrei.
  • It is best to use chemical pogmim that have no food application
  • One may taste and spit out boiler water to make sure it is sufficiently pagum


  1. Although bitul of ta’am lifgam is not permitted lichatchila, in situations where there is no kavana to be mivatel the issur and the bliya (through the kli) is only a safek, it is permitted.
  2. A standard CIPcaustic cycle contains 1-2% caustic in combination with other surfactants
  3. Additionally, it is possible that enough davar hapogem did travel with the steam to impart a ta’am lifgam into the next product. Since the product initially had a chezkas pagum, we remain with that chazaka.
  4. Rivash (siman 258) cited by Rama (Y.D. 108:5)
  5. Shach 42:4 offers a differing approach that would not necessarily allow te’ima on safek issur. However, there is no reason to assume that he would not allow te’ima by a davar pagum.
OU Kosher Staff