S'well Review, Is S'well Non-Toxic?
PFAS Authority is a scoring system, not a laboratory. We do not test products ourselves. Grades are model-based, built from published ingredients, materials, certifications, brand disclosures and third-party lab results where they exist. See the rubric.
Across 7 graded products, S'well averages Excellent (88/100). On disclosure, the brand says nothing publicly about PFAS. 7 of its products grade Good or better. Grades are model-based estimates, not lab results.
Worth buying from S'well Good or better, safest first
S'well
40 oz Stainless Steel Traveler
18/8 stainless steel interior and exterior, plastic lid components
BPA & bisphenols
S'well does not disclose the specific plastic resin or additive chemistry of the lid.…
Plastic lid degradation over time
All plastic lids degrade through repeated thermal cycling, UV exposure, and contact with…
Lid seal integrity loss
The seal gasket (typically silicone or rubber) can deteriorate, crack, or harden over…
Lower concern; bare stainless steel vessel, verify lid material separately.
✓Bare metal or glass, no coating at all
S'well
Recycled Stainless Steel Explorer 24oz Green Jasper
Recycled stainless steel, no coating disclosed
Bacterial growth in seams or caps
The bottle's gasket, lid interior, and seams may harbor bacteria if not dried thoroughly…
Low concern. Bare stainless steel carries minimal PFAS risk.
✓Bare metal or glass, no coating at all
S'well
S'ip by S'well Takeaway Mug
Stainless steel exterior, insulated
BPA & bisphenols
S'well states products are BPA-free, but independent lab confirmation of all interior…
Bacterial growth in lid seals
Silicone or rubber gaskets can harbor Listeria, E. coli, or mold if moisture is trapped…
Thermal shock or seal failure from temperature cycling
Repeated exposure to boiling water followed by cold storage can stress the bond between…
Low concern. Stainless steel design with no reported coatings.
⚠Brand says nothing about PFAS
S'well
Vacuum Insulated Travel Mug with Handle
Stainless steel body, plastic handle and cap
Plastic cap/handle thermal migration
Polypropylene handles and caps may release trace amounts of oligomers or processing…
Undisclosed polymer type and additives in handle/cap
S'well does not publicly specify whether the plastic handle is virgin or recycled…
Vacuum seal degradation and mold growth
If the cap gasket or seal is damaged, moisture can enter the vacuum cavity, leading to…
PFAS
S'well has made no public commitment to PFAS testing, BPA-free certification, or heavy…
Low concern, though S'well discloses no PFAS information.
⚠Brand says nothing about PFAS
S'well
S'ip by S'well Travel Mug
Stainless steel with plastic lid components
BPA & bisphenols
S'well does not disclose lid polymer type or BPA-free status; most commodity…
Bacterial growth in lid crevices and seals
The lid threading and gasket interfaces can trap moisture and organic residue, creating…
Microplastic shedding from lid wear
Repeated threading, unthreading, and dishwasher cycles may gradually fragment or abrade…
Lower concern; brand silence on materials limits certainty.
⚠Brand says nothing about PFAS
S'well
Mug Pink
Stainless steel double-wall vacuum insulated
Nickel leaching from stainless steel
18/8 stainless contains 8% nickel. While FDA-approved for food contact, prolonged…
Vacuum seal degradation
Repeated temperature cycling or impact can compromise the seal integrity, allowing…
Lid or seal material hazards
S'well mugs typically include a plastic or silicone lid (product imagery suggests…
Low concern. Stainless steel construction unlikely to hold PFAS.
⚠Brand says nothing about PFAS
S'well
24oz Tumbler with Straw
Stainless steel double-wall with plastic lid and straw
BPA & bisphenols
Polypropylene lids and straws may contain trace additives (including plasticizers or UV…
Microplastics
Repeated washing, freezing, or UV exposure can cause the plastic lid and straw to…
Rubber gasket degradation and mold growth
User reports on consumer forums describe mold or odor buildup in the rubber seal if not…
Lid printing or coating adhesion
Some S'well lids bear printed logos or text. If the printing uses non-food-safe inks or…
Low concern. Stainless steel core unlikely to hold PFAS.
⚠Brand says nothing about PFAS
Every grade uses the same public rubric. How grades work →