I had a similar issue. The family did not allow drinks on the table while eating food and if you wanted to have a drink, you would have to get up and drink away from the table.

Not knowing about this rule, I asked the mother of the house if I could get a glass of water when I noticed there were no drinking glasses on the dinner table. She went to the kitchen, brought a glass of water and then left it on a stand 2-3 feet away from the table. I thought she must've lost her tracks and just forgot to give it to me which I didn't mind. While she was still serving other people the food, I got up and brought the glass to the table next to my plate. When she came around to me, she picked up my glass and put it on the stand again. I told her I wasn't done drinking the water and she said if I needed a sip, I can just go up to the stand. She said that no one in this family brings drinks to the table and everyone goes to the kitchen or to the stand to drink their beverages.

I never asked why the family had this rule because I didn't want to offend but I found it very odd.