Nalgene is one of the most durable water bottle brands available — virtually unbreakable, lightweight, and used by outdoor enthusiasts for decades. Nalgene transitioned from polycarbonate to Tritan plastic after BPA concerns, and Tritan is BPA-free and BPS-free. For many users, Nalgene Tritan is a meaningful improvement from the original BPA-containing version. However, it is still a plastic bottle, and plastic leaches small amounts of chemicals over time — particularly with heat, UV exposure, and repeated use with acidic beverages.
Klean Kanteen uses 18/10 food-grade stainless steel with no interior coating. Stainless steel is not a polymer — it does not have plasticizers, stabilizers, or polymer additives that could migrate into water. The material is stable across temperature extremes and does not degrade over time the way plastics do. Klean Kanteen is also a Certified B Corp with published material sourcing transparency.
Klean Kanteen rates 'best'; Nalgene Tritan rates 'caution.' If you currently use a Nalgene and experience no issues, it is not a high-risk product. But for anyone evaluating a new bottle purchase — especially for daily all-day hydration, hot beverages, or children — stainless steel is the more defensible long-term choice. The switch from Nalgene to stainless is one of the most cited low-tox swaps in the reusable bottle space.