S'well · Insulated Travel Mugs
S'well 24oz Tumbler with Straw
Low concern. Stainless steel core unlikely to hold PFAS.
Stainless steel double-wall construction is inherently PFAS-free without coating. The brand doesn't disclose PFAS testing, and the plastic lid and straw are lower risk than treated products.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel double-wall with plastic lid and straw
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
What’s concerning
Category baseline
PFAS exposure happens more often with clothing products.
No PFAS disclosure
The company has not publicly discussed PFAS in this product.
BPA & bisphenols
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.
Source: FDA ↗Microplastics
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.
Source: EPA ↗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.
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’s reassuring
Safe base material
Made from ceramic, mineral, or natural fiber with no PFAS risk.
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.
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.
What we don’t know
- Basis
- Model estimate, 72% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- S'well has made none
Formulations change between production runs, so check the current label. How we grade.
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✓Bare metal or glass, no coating at all
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.