As always, buyer – or giftee – beware.  Not all stainless steel water bottles are the same.  Here is a mini cheat sheet to help identify substandard canteens:

• Material: You want 304 or 18/8 stainless steel, which is food-grade material used by the food processing industry.  Avoid Eco Canteen – it is made of a cheap non-food-grade 201 stainless that may dent when dropped.  Also avoid Sigg – this metal water bottle is actually epoxy-lined aluminum that has had a history of leaching bisphenol A (BPA).
• Finish: You want a tough powder-coated finish that won’t chip or flake.  Urban Canteen stainless steel water bottles are finished in the U.S. using a lead-free Dupont powder-coat paint that is hard baked on at 400° F.  Klean Kanteen bottles are liquid painted in China.    
• Caps: You want a cap made of stainless steel or a safe BPA-free plastic.  Urban Canteen offers both in a total of six cap types.  Unlike Kleen Kanteen, any cap can be paired with your bottle purchase. 

There is a reason Eco Canteens sell so cheap - they are made of non-food-grade 201 stainless