S'well · Insulated Drink Tumblers
S'well Recycled Stainless Steel Explorer 32oz Onyx
Low risk. Bare stainless steel has minimal PFAS risk.
S'well's recycled stainless steel bottle is bare metal with no reported surface treatments or coatings. No PFAS-specific claims exist, but the material itself poses lower PFAS risk.
We flunk more products than we pass. This one earned its grade. How we grade
Material
recycled stainless steel, no known coating
Lab data
No public lab test
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What S'well Recycled Stainless Steel Onyx is made of, ingredients and materials
This bottle is constructed from recycled stainless steel (grade not publicly specified, but S'well typically uses 18/8 or similar food-grade alloys) with no applied interior coating or enamel. Bare stainless steel is chemically stable and does not leach metal ions into room-temperature beverages in meaningful amounts. The recycled content adds environmental value but does not alter the safety profile compared to virgin stainless steel.
What’s concerning
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
Seal and gasket off-gassing (rubber or silicone)
The lid seal and gasket composition is not disclosed; typical S'well lids use food-grade silicone or rubber, which have no hazard of this kind on record but are not formally certified by S'well. Minor VOC off-gassing from new seals is possible but dissipates quickly with use.
Nickel sensitivity from stainless steel contact
Stainless steel contains nickel (typically 8-12% in 18/8 alloy). Individuals with severe nickel allergy may experience skin irritation on lips during drinking, though systemic nickel ingestion from water contact is negligible. This is an edge case and not a concern for most users.
What’s reassuring
Bare uncoated material
Recorded as a bare, uncoated material with no surface coating or treatment.
Lead
Bare stainless steel does not leach significant amounts of heavy metals into cold or room-temperature beverages. S'well has not published independent testing for lead or cadmium content, but the material class itself carries minimal risk at rest.
Source, ATSDR ↗Microplastics
This product has no interior coating (polymer, enamel, or ceramic), eliminating the risk of coating flaking or microplastic release. This is a material advantage over many insulated bottles.
Source, EPA ↗How is this PFAS grade calculated?
The brand's record and disclosure
S'well does not publish detailed material disclosures or third-party certifications (BPA-free claims, lead testing, etc.) on their website, and the brand has made no public commitment to PFAS avoidance or testing. This silence is not unusual for drinkware makers, but it means independent verification of heavy metal content or manufacturing process controls is unavailable. No recalls or safety controversies have been established in public records for S'well stainless steel bottles.
How it compares in its category
Bare stainless steel has lower concern for coating-degradation and microplastic risks compared to plastic bottles and has not been linked to the potential leaching issues associated with some ceramic or enameled alternatives. S'well's premium positioning and recycled material marketing are consistent with market leaders like Hydro Flask and Klean Kanteen, which also offer uncoated stainless options without extensive third-party safety disclosure.
If you buy it
Hand wash or use a bottle brush to avoid abrasive dishwasher damage to the exterior finish; stainless steel is durable enough for everyday use and unlikely to degrade in normal conditions. Avoid prolonged contact with acidic beverages (lemon juice, vinegar) if concerned about minor surface oxidation, though this does not pose a health risk. The bottle should last many years; replace only if the seal degrades or visible damage occurs.
What is not known about PFAS in this product?
- Basis
- Model estimate, 82% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- S'well has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
What are the PFAS-free alternatives to S'well Recycled Stainless Steel Explorer 32oz Onyx?
- Stainless steel bottle, stainless steel cap
- The brand calls it PFAS-free, which we have not verified
- Powder-coat cap degradation over time
3 hazards checked on this product, all on its full breakdown.
- Stainless steel body, powder-coat finish
- The brand calls it PFAS-free, which we have not verified
- Powder-coat finish degradation
3 hazards checked on this product, all on its full breakdown.
- Stainless steel bottle, plastic cap and silicone gasket
- The brand calls it PFAS-free, which we have not verified
- Silicone gasket degradation and leaching
3 hazards checked on this product, all on its full breakdown.
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.