you're allowed to take and drink bottled water in court

I missed out on jury duty here some years ago specifically because I wasn't allowed to do this! Up until late last year I was chugging down Questran three times a day - an especially awkward medication which comes as a gritty white powder you have to mix with water. I was told this couldn't be accomodated in court and had to keep faxing them the same medical certificate over and over for months. ffs