The default method of fasting is to abstain from all food and drink, including water, until the prescribed hour - such as 3 pm, for example. As a technical matter, the consumption of anything at all breaks the fast. (Thus, there is no such thing as "fasting foods" - technically speaking.)
Metropolitan George likely refers to alcoholic drinks as is evidenced by the use of the word 'упиватися' - hardly a term that is often used for water. Additionally, the normative fast in the Studite Typikon in use in the 11th century always includes water at the meal which breaks the fast on Wednesdays and Fridays; thus, the instruction not to drink must refer to alcoholic drinks. Furthermore, the instruction to eat two meals on feast days and to drink three cups at the first meal and two at the second also appears to refer to alcohol. the Metropolitan was a Greek and likely drank wine (albeit, diluted with water in the customary manner of the Greeks), which was also available at the Prince's court. It is not clear whether wine was in wide use outside the court - especially, as one travels further north. It is more likely that kvass and small beer was consumed on any day of the year, including at the Wednesday or Friday meal, and mead or ale was offered on feast days.
I'm curious if drinking refers to water or wine?
The default method of fasting is to abstain from all food and drink, including water, until the prescribed hour - such as 3 pm, for example. As a technical matter, the consumption of anything at all breaks the fast. (Thus, there is no such thing as "fasting foods" - technically speaking.)
Metropolitan George likely refers to alcoholic drinks as is evidenced by the use of the word 'упиватися' - hardly a term that is often used for water. Additionally, the normative fast in the Studite Typikon in use in the 11th century always includes water at the meal which breaks the fast on Wednesdays and Fridays; thus, the instruction not to drink must refer to alcoholic drinks. Furthermore, the instruction to eat two meals on feast days and to drink three cups at the first meal and two at the second also appears to refer to alcohol. the Metropolitan was a Greek and likely drank wine (albeit, diluted with water in the customary manner of the Greeks), which was also available at the Prince's court. It is not clear whether wine was in wide use outside the court - especially, as one travels further north. It is more likely that kvass and small beer was consumed on any day of the year, including at the Wednesday or Friday meal, and mead or ale was offered on feast days.