Using a pre-emptied plastic bottle is definitely not healthy as it is designed for one use and will begin to break down after one use, emitting carcinogenic pthalates.
Glass is ideal for water but it isn't easy to find a good glass bottle and it also has problems of weight and safety if you're taking it walking.
Polycarbonate is the only safe plastic for water storage. You will get thousands of uses with a polycarbonate bottle.
Holds a handy 1 litre.
Ok