So, how do you know if a stainless steel water bottle is really safe to drink from? Flaske, a maker of environmentally friendly products like water bottles, recommends buying only those made from high-quality 18/8 stainless steel.
What is 18/8, and why is it so safe? According to Corrosionpedia, 18/8 (also known as 304 grade) denotes stainless steel made using a composition of 18% chromium, and 8% nickel. This form of stainless steel is durable, easy to clean, and is resistant to oxidation and corrosion (like from acidic liquids).
As Flaske notes, scratches, dents or aging won’t transform 18/8 stainless steel into a material that leaches chemicals into water. Further, these water bottles require no liner, unlike aluminum bottles, ensuring the taste of the water remains free of “bad tastes.” Iron Flask, another maker of insulated stainless steel water bottles, echoes this 18/8 recommendation, saying that among the many reasons to go with 18/8 stainless steel, safety is No. 1.