S'well · Insulated Travel Mugs
S'well 24oz Tumbler with Straw
Lower concern. Stainless steel core unlikely to contain PFAS.
S'well tumblers use stainless steel construction, a PFAS-free material. Brand does not disclose PFAS testing. Plastic lid and straw merit caution but are lower risk than coated or treated products.
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Stainless steel double-wall with plastic lid and straw
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Safe base material
Made from a material with no inherent PFAS use (ceramic, mineral, or natural fiber).
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
The S'well tumbler uses food-grade stainless steel (typically 18/8) as its inner and outer walls, which is chemically inert and does not leach metals or require non-stick coatings. The plastic lid and straw are the points of concern: these are typically polypropylene (PP) or similar thermoplastics. Because the stainless steel core does not come into contact with hot liquids directly (the double-wall design insulates), migration of plasticizers or other additives from the plastic components is minimal under normal use.
The brand's record and disclosure
S'well has not published detailed material certifications or PFAS statements; this silence is typical for lifestyle drinkware brands but limits transparency. No recalls or confirmed safety incidents involving this product line are on public record. The brand markets durability and safety implicitly through its premium positioning, but does not independently verify third-party testing of its plastic components.
How it compares in its category
The S'well tumbler is safer than ceramic or coated-aluminum tumblers that may shed glazes or corrode. It avoids the non-stick coating hazards (Teflon-type coating off-gassing risk) present in some insulated cookware. The main trade-off versus glass or borosilicate options is that plastic lids and straws introduce minor chemical exposure; however, stainless steel core design keeps that risk lower than single-wall plastic bottles.
If you buy it
Do not heat the tumbler in a microwave or boiling water; hand-wash the lid and straw to avoid dishwasher heat stress on plastic. Inspect the rubber gasket and plastic seals annually for cracks or discoloration, which indicate degradation. Replace the straw or lid if they show cloudiness, cracks, or odors. The stainless steel body itself should last years; focus maintenance on the plastic components.
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.”
BPA/BPS and plasticizers in lid and straw
Polypropylene lids and straws may contain trace additives (including plasticizers or UV stabilizers) not publicly disclosed by S'well. Risk is low if lid/straw do not contact hot liquids directly; cold or warm (under 60°C) use presents minimal leaching.
Microplastics from plastic degradation
Repeated washing, freezing, or UV exposure can cause the plastic lid and straw to micro-fracture over time. Fragments are unlikely to be ingested in meaningful quantities, but replacement after 2-3 years of heavy use is prudent.
Rubber gasket degradation and mold growth
User reports on consumer forums describe mold or odor buildup in the rubber seal if not dried immediately after washing. This is a maintenance issue, not a material defect, but indicates the design traps moisture; regular disassembly and air-drying are necessary.
Stainless steel corrosion and nickel leaching
Food-grade 18/8 stainless steel is highly corrosion-resistant and does not leach nickel under normal beverage use. No incidents reported for this product. Risk is effectively zero for this material grade.
Lid printing or coating adhesion
Some S'well lids bear printed logos or text. If the printing uses non-food-safe inks or adhesives, prolonged contact with acidic beverages (lemon water, vinegar) could cause flaking. S'well does not publicly detail ink or coating specifications.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 72% 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.
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More insulated travel mugs 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.