1. No harmful plastic chemicals potentially leaching into my water.
2. Washable and reusable
3. More frugal than plastic - if I were to purchase 10 water bottles per month at the gas station (which are around $2.00 each) I would spend $20 + tax. Multiply that by 12 months out of the year and I would spend $240 + tax. A stainless steel water bottle is usually between $20 and $30 and should last a long time.
4. Less waste
5. The stainless steel bottle that I have (more to come on the awesome bottle I have) is triple walled so there is no condensation on the outside when I put ice in my water.
6. I put water and ice in it the other morning and I had to fill it up with water 3 times during the day because I drank it all, but the ice did not melt until later that evening.
7. Because of the triple wall my water stays cold for a LONG time.
8. Stainless Steel (if food grade) is non porous so it is easy to clean.
9. It is pretty :)
10. I can use it for hot drinks too.
11. I would much rather drink my well water than bottled water that I have no idea how it has been treated or where it came from. If you research this, you may not want to drink another plastic water bottle from the store :)