Tritan is an Eastman Chemical product marketed as BPA-free and BPS-free, and it has been widely adopted in water bottles, food containers, and children's products as a safer plastic alternative. The BPA-free claim is accurate — Tritan does not use bisphenol-A in its formulation. However, 'BPA-free' does not mean chemically inert. Research has identified other estrogenic activity in Tritan-derived leachates, and the plastic still contains additives and stabilizers not fully disclosed publicly.
Stainless steel is a metal alloy, not a polymer, and it does not leach chemicals into water under normal conditions. High-quality 18/10 stainless steel (food-grade) is remarkably stable and used in everything from surgical instruments to water supply infrastructure. With no polymer additives, no stabilizers, and no plasticizers, there is essentially nothing to migrate into the water.
Stainless rates 'best'; Tritan rates 'caution.' Tritan is a significant improvement over polycarbonate (BPA-containing) plastic, but it is still plastic — and the question of what is in plastic beyond the disclosed ingredients remains open. Stainless steel sidesteps that question entirely. For anyone who has already switched away from polycarbonate to Tritan and wants to go further, a stainless steel bottle is the natural next step.