S'well 17oz Water Bottle With Flip Straw Cap
Lower concern, standard insulated bottle with no known PFAS-prone components, but cap material undisclosed.
Stainless steel vacuum insulation poses lower PFAS risk. BPA-free plastic flip-straw cap is claimed, but S'well doesn't disclose whether cap plastic or seals contain PFAS.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel double-wall vacuum insulation; BPA-free plastic flip-straw cap
Lab data
No public lab test
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What S'well 17oz Water Bottle Flip Straw Cap is made of, ingredients and materials
The S'well 17oz uses 18/8 stainless steel (austenitic grade) for the double-wall vacuum insulation layer, which is chemically inert and does not leach metals into water under normal use. The flip-straw cap is plastic (material type not publicly specified by brand), marketed as BPA-free. Stainless steel is a material not linked to PFAS concerns for water bottles because it has no polymer matrix to degrade or off-gas, and 18/8 grade resists corrosion even with acidic beverages.
What’s concerning
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Cap plastic composition and leaching
The flip-straw cap material is not disclosed by S'well despite BPA-free labeling. Unknown plastics may include polypropylene or other polymers; risk of minor leaching or off-gassing increases if cap is heated or aged, but is lower for cold water storage at room temperature.
Cap adhesive or coating degradation
The joint between the plastic cap and stainless bottle body may use adhesives or gasket materials not disclosed by the brand. Over years of use, thermal cycling and wear could theoretically cause minor degradation, but no consumer reports of this issue are documented.
Mold or bacterial growth in straw
The flip-straw design creates a narrow interior passage that can trap moisture and food residue if not cleaned thoroughly after use. While S'well does not market antibacterial technology, this is a maintenance risk common to all straw bottles; regular disassembly and drying mitigates it.
What’s reassuring
Bare uncoated material
Recorded as a bare, uncoated material with no surface coating or treatment.
Stainless steel nickel content
18/8 stainless steel contains 8% nickel. People with nickel sensitivity may theoretically experience reaction; however, nickel migration from properly manufactured stainless bottles into drinking water is negligible under normal conditions because the oxide layer is stable and non-reactive.
Volatile organic compound (VOC) off-gassing from cap
No VOC testing or off-gassing complaints are on record for S'well caps. Stainless steel does not off-gas; risk is limited to the plastic cap, which is likely minimal for room-temperature water storage but cannot be confirmed without material disclosure.
How is this PFAS grade calculated?
The brand's record and disclosure
S'well (owned by Igloo Products) does not publish detailed material composition or third-party safety certifications on its website. The brand markets products as BPA-free but does not disclose cap polymer type, manufacturing standards, or responses to consumer safety inquiries. No recalls or regulatory actions against S'well bottles have been publicly documented. The lack of proactive disclosure is typical for the direct-to-consumer drinkware category but limits independent verification of cap material safety.
How it compares in its category
Insulated stainless steel bottles (S'well, Hydro Flask, Klean Kanteen) carry lower chemical risk than plastic-bodied alternatives because the primary contact surface is inert metal. S'well's pricing and design positioning place it in the mid-to-premium segment; it does not filter water (unlike Brita or LifeStraw bottles) so there is no risk of bacterial colonization in a filter cartridge. The main differentiator from competitors is the flip-straw cap design, which is convenient but introduces a plastic component whose material composition remains undisclosed.
If you buy it
Hand-wash the cap and straw to avoid prolonged exposure to hot dishwasher water, which may accelerate plastic degradation or off-gassing if the cap polymer is not heat-resistant. The stainless steel body is durable and temperature-safe for hot and cold beverages. Inspect the cap regularly for cracks, discoloration, or odor; replace if visible damage occurs or after 2-3 years of daily use, as plastics degrade over time. Avoid leaving acidic drinks (lemon water, apple juice) in the bottle for extended periods, though stainless steel resists most household liquids.
What is not known about PFAS in this product?
- Basis
- Model estimate, 72% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- S'well has made a specific claim
Formulations change between production runs, so check the current label. How we grade.
More water filters 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.