Hydro Flask Standard Mouth Water Bottle (Stainless Steel, Flex Cap)

Important Note on Water Bottles & Drinkware

When I’m choosing bottles, I focus on what actually contacts my drinks. I avoid nonstick coatings, per- and polyfluoroalkyl substances (PFAS), aluminum in the liquid path, heavy metals like lead and cadmium, and materials that rely on chemical finishes or nanoparticles. I look for borosilicate glass or stainless steel where the liquid sits, knowing that not every bottle will be completely plastic-free. If you want reusable water bottles to last, I recommend opting for 18/8 stainless steel and purchasing from brands that are clear about their material details. Some bottles use 430 stainless steel (18/0) — meaning 18% chromium and 0% nickel — which tends to be less corrosion-resistant than 18/8, so I personally look for 18/8 when durability matters.

Product Description

The Hydro Flask Standard Mouth water bottle features a double-walled vacuum-insulated stainless steel body with a flexible cap. It’s designed to keep drinks cold or hot for hours and is marketed as BPA-free and dishwasher-safe.

What I Like

I like that the drink-contact surface is stainless steel, which doesn’t require coatings and won’t leach into liquids. Hydro Flask clearly states the bottle is BPA-free, which feels like the next best option when a design includes plastic components in the lid.

Things to Keep in Mind

The cap and surrounding components include plastic and silicone parts. While those don’t contact the liquid directly, they are still present in the design. If minimizing all plastic contact is your priority, consider bottles with borosilicate glass bodies or all-metal lids where possible. That said, this bottle does a good job keeping your drinks in stainless steel and avoiding PFAS, coatings, and aluminum in the liquid path.