Q. How many seconds does one have to drink a reviis of water to make a borei nefashos? Does it make a difference if it is soda or wine? Thank you.

A. Mishna Berura (210: 1) quotes O.H. (612: 12) that in regards to drinking a reviis for the purpose of reciting a bracha achrona or compliance of a mitzvah, if one drank and stopped a bit and then drank again until he completed dinking the full reviis, it is not considered as having drank a full reviis. In Shaarei Tzion (ibid. 11) he mentions that most people drink a reviis while stopping once and it is still counted as one single act. He also quotes the opinion of the Gr”a that maintains that when drinking we also use the same time measure we use when eating solid food. Namely, the time it takes to consume a prass measure of bread, which can be from two to nine minutes, following the opinion of different Poskim. Mishna Berura (ibid.) maintains that in regards to drinking hot tea and coffee, which is consumed slowly, the established minhag is not like the Gr”as’ opinion and we do not recite the bracha achrona after drinking done within achilas prass. He also mentions that it is proper to leave a reviis in the cup until it cools enough to be drunk as required, and then recite the last bracha. (Shaarei Teshuva ibid. disagrees).
Hagadah Kol Dodi (20: 11) rules that the above applies only to unsweetened wine, that people consume in two sips. However, sweet wine and other drinks, people may drink a reviis in one single sip. He also explains that sipping the drink into ones mouth is not the same as swallowing, which may require a few more gulps for swallowing a full reviis.
Horav Shlomo Miller’s Shlit’a opinion is that you may relay on the Gr”as’ opinion if you include other doubtful conditions such as the shiur or amount that constitutes a reviis. E.g., although normally we maintain the smallest reviis shiur to be 86cc (approximately three ounces), for the purpose of bracha achrona even two ounces or 58 cc, would suffice when consumed in one or two sips, if also a regular reviis (86 cc) was drunk within a three or four minutes period. Alternatively, one should consume an olive sized solid food (approximately 28 grams) and recite Bore Nefashos on both the solid and the liquid.

Rabbi A. Bartfeld as revised by Horav Shlomo miller Shlit”a