Klean Kanteen · Insulated Drink Tumblers
Klean Kanteen Stainless Steel Tumbler - Rust
Lower PFAS concern; bare stainless steel tumbler.
Klean Kanteen tumblers are made of uncoated stainless steel with no surface treatments known to contain PFAS. No brand PFAS disclosure found, but the bare material poses minimal risk.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel, bare uncoated
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Uncoated safe material
Bare, uncoated material (cast iron, stainless, carbon steel, or glass) with no surface treatment to contain PFAS.
Category baseline
other is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
The full breakdown
What it's made of and why it matters
This tumbler is constructed from 18/8 stainless steel (18% chromium, 8% nickel), which is one of the most chemically inert food-contact materials available. The "bare" uncoated design means there are no ceramic glazes, epoxy linings, non-stick coatings, or enamel layers that could degrade, chip, or leach over time. Stainless steel itself does not off-gas volatile organic compounds (VOCs) and is resistant to corrosion under normal use conditions.
The brand's record and disclosure
Klean Kanteen has built its market position around stainless steel drinkware and does not publicly disclose PFAS-related testing or third-party certifications (such as NSF or Berkeley or PFS test reports). The company's silence on PFAS is not unusual for stainless steel manufacturers, since the material class itself carries lower inherent PFAS risk than coated alternatives. No documented product recalls or safety controversies are on record for this product line.
How it compares in its category
Bare stainless steel tumblers occupy the lower-hazard end of the drinkware spectrum compared to ceramic glazed cups (potential lead/cadmium), plastic tumblers with linings (BPA/BPS, coatings), or vacuum-insulated models that may use epoxy or polyester coatings inside the walls. The trade-off is lack of insulation; this tumbler conducts temperature readily. As a category choice, uncoated stainless is one of the safest options available for repeated hot and cold beverage use.
If you buy it
Hand wash with mild detergent; dishwasher safe but hand washing extends appearance. Avoid prolonged contact with highly acidic or salty foods (vinegar, citrus, salt brines) which can slowly etch stainless over years, though this is cosmetic rather than a safety issue. Do not use with temperatures above 212F (boiling water is fine). Replace if dents accumulate or the material develops small cracks, as these can trap bacteria, though stainless steel itself resists corrosion.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Nickel leaching from stainless steel
18/8 stainless steel does contain nickel (approximately 8%). Under normal use with water and neutral foods, leaching is negligible; however, prolonged contact with acidic beverages or very hot liquids may increase microscopic nickel migration. This is relevant only for individuals with diagnosed nickel sensitivity or dermatitis.
Coating degradation (absent)
No enamel, glaze, ceramic, or resin coatings are present on this bare stainless steel tumbler, eliminating risks of chipping, peeling, or leaching that affect coated drinkware. This is a material strength of this product.
Thermal conductivity hazard
Bare stainless steel conducts heat readily; very hot liquids will make the exterior of the tumbler hot to the touch, posing a burn risk if held without caution. This is a use-related hazard, not a chemical one, but relevant to safe handling.
Chromium leaching from stainless steel
High-quality 18/8 stainless steel (like 304 grade commonly used in food ware) is highly resistant to corrosion and leaching of chromium under normal beverage use. Chromium release is not a documented concern for this material class in food contact applications.
Bacterial or mold growth inside seams
If the tumbler has welded or folded seams, bacteria or mold can accumulate in crevices if not dried thoroughly after washing. Inspect for accessible seams and ensure complete drying; this is a maintenance issue rather than an inherent material hazard.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 88% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Insulated Drink Tumblers
Reduce
Halo Tumbler
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✓Naturally PFAS-free material
Cuppa
To Go Tumbler
Stainless steel with plastic lid
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✓Naturally PFAS-free material
Klean Kanteen
Steel Pint
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Lower PFAS concern. Bare stainless steel container, no coatings.
✓Bare metal or glass, no coating at all
More insulated drink tumblers grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.