Since Singapore is such a hot country, it is important for students and adults to keep hydrated to avoid heatstroke. One of the most popular and best brands of water bottles is Nalgene, which is made in the USA.
It is BPA free, which is very important to avoid drinking toxic plastic particles that may leach into your water. (I think by now Singaporeans know it is not good to reuse Coca Cola bottles as your water bottle; 10 years ago it was very common to do that.)
It is quite hard to find Nalgene bottles in supermarkets. NTUC Fairprice, Giant does not seem to carry them in their stock.
Interested buyers may purchase Nalgene bottles from Qoo10 (see image link below). Do choose this store as it has many positive reviews, it has an actual store in Pasir Ris, but buying online would be much more convenient.
For our international readers, Nalgene is also available on Amazon: