Owala SmoothSip Slider Stainless Steel vs Cold Tumbler: which is safer?

Ember Cold Tumbler is the clear pick. Owala SmoothSip Slider Stainless Steel carries a failing PFAS grade, and we never recommend buying a failing product.

Cuppy

Owala SmoothSip Slider Stainless Steel

PFAS grade

F 55/100

Overall grade

F 47/100

Verdict

Skip

Hazard flags

⚑ 2

Material

Stainless steel body, silicone slider lid

Confidence

82%

PossibleMicrobial growth and biofilm in slider mechanism

PossibleStainless steel manufacturing residues (oil, metal fines)

Why this grade

Our pick

Ember

Cold Tumbler

PFAS grade

A 100/100

Overall grade

A 92/100

Verdict

Buy

Hazard flags

⚑ 2

Material

stainless steel with silicone seal

Confidence

72%

PossibleSilicone seal degradation and microbial growth

PossibleCoatings or adhesives on printed logos

Why this gradeBuy

Both products run through the same public rubric: materials, coatings, brand disclosure, lab findings, and recalls, plus a beyond-PFAS hazard analysis. Grades are model-based estimates, not lab tests. How grades work →

More insulated travel drinkware: see the full ranking