As-salaam-alaikum.
In the book Tibb-e-Nabawi, it is mentioned that we should NOT drink water during & immediately after meals EXCEPT to drink
after a break/gap of over 1/2 hour.
Also, the Hakeems in India insist on the same theme. I am sure it is wise.
I remember that I was told that it is sunnah but I do not have hadiths to back.
BUT I would request quotation of one or two authentic “Hadith” of Prophet Mohammed (s.a.s), in this regard since it will be very
easy for Muftis to quote from the vast treasure, alhamduliAllah, which they possess.
I shall be obliged to receive a positive response to my request, at an early date, for the benefit of my family & friends and the Ummah at large.
Jazakum Allahu khairan.
الجواب وبالله التوفيق
It has been documented in Fatawah Darululoom ZakriyahPg. 248, Vol. 6 with reference to Madarij, that Rasulullah Sallallaho Alyhi Wasallam did not drink water immediately after eating.
It is injurious for the stomach and the digestive system to drink water immediately after eating; therefore one should wait for some time before drinking water.
Fatawah Darululoom Zakriyah, reference to Shumail-KubrahPg. 248, Vol. 6
واللہ اعلم بالصواب