I have a habit of drinking Fiji water. It's a terrible habit but it tastes great. The bottle I have in my recycling bin has another year and a half on its best by date. Microplastics might be a concern, but I'd be surprised if it's not safe to drink for many years after the best by date.
Bottled water in France at least has a 1-year expiration date. I have drunk water well past this date without noticing any particular taste.