I don’t buy bottled water. Apart from the plastic pollution problem, it takes 2L of water (some sources say much more than this) to manufacture a 1L plastic bottle, and who knows how far it has had to travel to get to you. These points really make it a ridiculous choice. Overall, Tap water has 1% the environmental impact of bottled water (reference).
Choosing tap water over other drinks when out and about is also important for reducing waste. So before grabbing that takeaway glass bottle of juice or can of soft drink, think twice about whether you need that treat today (this works for me). And if you do need it, make sure you recycle the packaging.
It’s a good idea to get in the habit of having a glass or stainless steel water bottle handy at all times. OR you could slow down, sit down and order something like a freshly squeezed juice – just make sure you refuse the straw.