S'well · Filtered Water Bottles
S'well Stainless Steel Water Bottle
Lower PFAS concern, stainless steel construction avoids typical Teflon-family coating coatings, but brand makes no public PFAS commitment.
S'well bottles are made from food-grade stainless steel with no reported non-stick or water-resistant coatings that would typically require PFAS. The material itself poses lower inherent PFAS risk compared to coated or treated products.
Shop S'well on Amazon →Material
Double-wall 18/8 stainless steel
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
No PFAS disclosure
No public statement about PFAS in this product.
Uncoated safe material
Bare, uncoated material (cast iron, stainless, carbon steel, or glass) with no surface treatment to contain PFAS.
The full breakdown
What it's made of and why it matters
S'well bottles use double-wall 18/8 stainless steel (austenitic grade containing 18% chromium and 8% nickel), which is a food-contact-safe alloy that does not leach metals into water under normal use. The double-wall design creates an air pocket for insulation without requiring chemical coatings, polymeric liners, or adhesives that could degrade. Unlike aluminum or coated steel bottles, 18/8 stainless steel resists corrosion and does not require protective enamels or ceramic coatings that historically contained lead or cadmium.
The brand's record and disclosure
S'well has not published explicit PFAS avoidance statements or third-party certifications (NSF, FDA, or similar) on its website. The brand does not appear in major product safety controversies or FDA recalls related to leaching. S'well's marketing emphasizes durability and material purity but lacks transparent testing disclosures or ingredient documentation typical of premium consumer-safety-focused brands. No independent testing of S'well bottles for heavy metals or contaminants has been published in accessible sources.
How it compares in its category
Stainless steel bottles are among the safest options in the water bottle market because they avoid epoxy-lined aluminum (which can leach BPA or other estrogenic compounds) and plastic bottles that may off-gas or degrade. S'well competes with Hydro Flask and Klean Kanteen, which similarly use 18/8 stainless steel with vacuum insulation. S'well does not use filters, so it avoids bacterial colonization or filter-media leaching risks present in filtered bottles (like Clearly Filtered or GRAYL models).
If you buy it
Wash the bottle with warm soapy water before first use and hand-wash regularly to prevent mineral deposits or biofilm. Avoid dropping the bottle, as impact can compromise the seal and allow water to enter the insulation chamber, which is difficult to dry and may harbor mold. Do not expose to extreme heat (dishwasher or boiling water) repeatedly, as thermal cycling can stress the double-wall seal over years. Replace the cap gasket if it becomes visibly cracked or if the seal no longer holds; replacement gaskets are readily available.
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.”
Metal leaching (chromium, nickel)
18/8 stainless steel is passivated during manufacturing to form a protective chromium oxide layer. Under normal use with neutral pH water (no acidic or highly alkaline liquids), leaching is negligible and well below FDA food-contact thresholds. No recalls or contamination reports for S'well stainless bottles have been published.
Coating degradation and flaking
S'well uses bare stainless steel construction without enamels, ceramic glazes, or non-stick coatings. There is no interior or exterior coating to peel or degrade. Exterior powder coating or paint (if present on color finishes) is not in contact with beverage.
Bacterial or mold growth
The insulation air gap in double-wall bottles is not accessible for cleaning. If the seal is compromised (crack or worn gasket), water can enter the gap and stagnate, potentially harboring mold or bacteria. This is a design limitation of vacuum-insulated bottles, not a material defect.
Microplastics or polymer degradation
Stainless steel bottles do not shed microplastics. The cap gasket (typically silicone) may degrade very slowly with repeated thermal cycling or wear, but silicone does not readily fragment into microplastics under normal handling.
Cap and closure safety (choking or leaching)
S'well caps are typically plastic or plastic-lined. The cap material, gasket, and threaded seal are not independently tested or disclosed. If the cap plastic is low-grade or degraded, it could theoretically leach unidentified compounds, though no specific recalls or complaints are documented.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 78% 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.
More filtered water bottles 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.