What's the most dehydrated a person can get without it making them ill? I was just feeling incredibly thirsty then I realised ove I've only had the past weekend I only had 1/2 a bottle of wine, a can of lager and 3 cups of tea to drink. And today just a cup of tea when I got to work. Plus, I haven't drank water in about 6 or 7 days. I suspect I should feel awful based on that, but don't.