S'well · Insulated Travel Mugs
S'ip by S'well Travel Mug
Lower concern; brand silence on materials limits certainty.
S'well travel mugs use stainless steel construction, an inherently PFAS-free material. No public PFAS disclosures exist; plastic lid components remain unspecified.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel with plastic lid components
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
S'well does not disclose lid polymer type or BPA-free status; most commodity polypropylene lids are assumed BPA-free, but absence of third-party confirmation leaves low risk unquantified. Minimal contact risk since the lid contacts only the mouth opening and cool/warm (not boiling) liquids.
Source: FDA ↗Bacterial growth in lid crevices and seals
The lid threading and gasket interfaces can trap moisture and organic residue, creating microenvironments for mold or bacteria if not dried thoroughly or rinsed regularly. This is not a manufacturing defect but a usage/maintenance risk inherent to all reusable lidded drinkware.
Microplastic shedding from lid wear
Repeated threading, unthreading, and dishwasher cycles may gradually fragment or abrade the plastic lid seal, introducing micro-plastic particles into beverages. Visible degradation (cracks, cloudiness) is a signal to replace the lid component.
What’s reassuring
Safe base material
Made from ceramic, mineral, or natural fiber with no PFAS risk.
Stainless steel nickel leaching (18/8 alloy)
High-grade 18/8 stainless steel (18% chromium, 8% nickel) is well-established as safe for beverage contact; nickel migration is negligible at room temperature and neutral pH. People with severe nickel allergies may experience skin irritation from touching the lid, but internal beverage contact poses minimal risk.
Plastic lid off-gassing or VOCs
No published off-gassing data for S'well lids; commodity polypropylene generally shows minimal VOC release at room or warm beverage temperatures. Risk is much lower than for plastic-bodied drinkware or freshly molded containers.
The full breakdown
What it's made of and why it matters
The S'ip by S'well features a 18/8 stainless steel interior and exterior, which is highly resistant to corrosion and does not leach metals under normal use. The plastic lid components (typically polypropylene or similar commodity polymers) contact only the beverage opening and rim, limiting exposure surface compared to fully plastic drinkware. Stainless steel is chemically inert and does not degrade with hot or cold liquids, making it one of the safest long-term beverage container materials available.
The brand's record and disclosure
S'well does not publish detailed material sourcing, manufacturing process, or chemical certifications (BPA-free claims, etc.) on its public materials, which is a notable transparency gap for a premium product. The brand has not faced major safety recalls or documented chemical contamination incidents in consumer reports. S'well's silence on PFAS and detailed polymer composition suggests either standard industry practice or deliberate opacity; without independent testing or certification data, the brand's actual safety vetting remains opaque.
How it compares in its category
Stainless steel insulated tumblers are among the safest drinkware options; the S'ip compares favorably to glass (breakage, thermal shock) and plastic-heavy alternatives (BPA/BPS leaching risk). Premium brands like Hydro Flask and Yeti use similar stainless construction with comparable (or equally undisclosed) plastic lid components. The main competitive disadvantage is S'well's lack of third-party certifications or published test data versus some competitors who claim NSF certification or published lead/cadmium screening.
If you buy it
Wash the lid and threads regularly with warm soapy water and allow to air dry to prevent bacterial biofilm and odor buildup, especially if the mug sits unused for days. Avoid prolonged contact with acidic beverages (lemon water, vinegar) in the lid crevices, as they may degrade seals or gaskets over time, though the stainless body resists this. Do not subject the plastic lid to direct high heat (dishwasher upper rack only, or hand wash) to minimize polymer stress; replace the lid if it becomes cloudy, cracked, or develops persistent odor. The stainless steel body itself is durable for years; the lid gaskets and seals typically need replacement every 1-2 years depending on use.
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.
Safer alternatives in Insulated Travel Mugs
Thermos
Stainless Steel King Travel Mug
Stainless steel interior and exterior, plastic lid
Plastic lid polymer degradation
Limited concern
Gasket/seal material composition
Limited concern
Thermal shock stress on seals
Limited concern
Lower concern; bare stainless steel has minimal PFAS risk.
✓Bare metal or glass, no coating at all
Thermos
Icon 16 oz Stainless Steel Mug
stainless steel, no stated interior coating
Seal degradation and bacterial growth
Limited concern
Lid or cup material (not specified)
Limited concern
Lower concern; bare stainless steel has minimal PFAS risk.
✓Bare metal or glass, no coating at all
Thermos
18 oz. Icon Vacuum Insulated Stainless Steel Mug
stainless steel exterior, vacuum insulation, stainless steel interior
Nickel leaching from stainless steel
Limited concern
Chromium leaching from stainless steel
Limited concern
Thermal shock and seal degradation
Moderate concern
Lower concern; stainless steel mug has no water-repellent coating.
✓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.