Owala SmoothSip Slider Coffee Tumbler Review: Real Lab Testing Results

We tested it in the Lab to be sure.

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Owala has become a mainstay in the trendy water bottle landscape for its playful colorways, but it deserves just as much credit for the innovative bottle designs. Its new SmoothSip Slider is a perfect example: This tumbler is specifically designed to hold coffee without fear of spillage, thanks to its leakproof lid.

In case you didn't already know, this isn't the brand's first venture into the coffee tumbler space. The existing SmoothSip tumbler is made with a strawless spout for easy sipping, but the newer SmoothSip Slider makes for a great travel coffee mug since the lid slides closed to keep spills at bay. Our experts at the Good Housekeeping Institute got their hands on the SmoothSip Slider to see if it's worth the hype.

Available in 12-ounce and 20-ounce capacities, this tumbler fits well in cup holders no matter the size. Plus, our testers confirm that it'll withstand spillage with its tight-fitting sliding lid. "This tumbler is confirmed leakproof when the slider is locked, but not leakproof when the slider is open," says Eva Bleyer, Kitchen Appliances Lab Reviews Analyst. She warns that if the slider is open, your liquid will pour out, so you do have to make sure it's locked correctly.

For safe measure, double check to ensure the lid is locked before throwing the tumbler in your bag. One quirk here: "It's slightly hard to know if your lid is locked unless you know which position the slider shoulder be in, there isn't a visual cue like other tumblers like something that covers drinking spout," Bleyer shares.

Also different from the original SmoothSip tumbler, the SmoothSip Slider is made with triple-walled insulation instead of double-walled insulation. Overall, a triple-wall design tends to be heavier but can help your drinks maintain temperature. After conducting a temperature test on the SmoothSip Slider, Bleyer found that the contents stayed hot for nearly six hours. Other testers also found the insulation to be a highlight, with one reviewer noting that their "ice water stayed cold" in their hot car when parked in the sun for four hours.

The manufacturer says that the lid is dishwasher-safe but the cup is handwash only. Take note that the slider might be hard to disassemble when cleaning. "Because I have arthritic thumbs, it was very difficult for me to remove the slider to wash before initial use," one tester says. "You have to press and push."

All in all, GH experts give this new tumbler a positive review for its spill-resistant and general user-friendly qualities. "The top is easy to unscrew," one tester adds. "It does not leak when full and set on its side (as long as the slider is secure)."

Like most new drops from Owala, it was in high demand and already sold out in six of the eight colors, but some options are still in stock. And if you'd like to add to your collection, we've shared more Owala best-sellers below, including top-tested picks like the FreeSip and kids' water bottles. These water bottles are available on Amazon for quick delivery, usually with a two-day shipping turnaround.

Nashia Baker is a commerce editor at Hearst Magazines; she covers all things home and lifestyle across brands such as Oprah Daily, Cosmopolitan, Delish, and Esquire. Before joining Hearst, she highlighted small business owners, creatives, and the best shoppable content.

Eva (she/her) is a reviews analyst in the Kitchen Appliances and Innovation Lab, where she tests kitchen gear, home appliances and culinary innovations. She graduated from NYU with a bachelor of science in food studies, nutrition and public health and is a trained chef through the Natural Gourmet Institute. Eva has more than 10 years of experience in the food industry, working as a food stylist, personal chef and marketing manager.

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