Gemara:

Sotah 

Halacha:

Beit HaKenesset,  Tefillah 

Collections: R' Grunstein Eating and Drinking in Shul

References: Sotah: 44B  

Description

From the perspective of the laws that govern davening Shacharit: 1) One shouldn't drink during ברכות קריאת שמע and obviously during the Amidah 2) If possible, not during חזרת הש"ץ through תחנון 3) During Pesukei Dezimra believe it's allowed, with room to be stringent 4) Between ישתבח to the onset of ברכות קריאת שמע it's permitted, as it is from אשרי onwards