The Cleaning Mistake That Is Ruining Your Thermos

When you purchased your trusty Thermos, you probably envisioned using it for years to keep your beverages warm; but one day, you notice your bottle is no longer maintaining the contents at a suitable temperature — why? A tried-and-true tip to best clean your kitchen is to boil dirty or hard-to-clean items to kill off bacteria. It's true that boiling water will eliminate almost any kitchen-based germ, and the Thermos is designed to be exposed to high temperatures, so it should be safe to clean your bottle with boiling water, right? Not so fast.

Somewhat confusingly, exposing your Thermos to water temperatures of 212 degrees Fahrenheit or above may result in collateral damage to your container as you attempt to decimate bacteria populations. While Thermos containers are made to withstand temperatures that other bottles would melt when exposed to, using excessively high temperatures when cleaning a Thermos can damage it, thus weakening its ability to maintain heat. The use of boiling water can risk melting some of the key components responsible for keeping a Thermos' warmth in, making this cleaning approach one to avoid.

It goes without saying that you do need to deep-clean your reusable bottle regularly — once a week if you use the bottle daily, once a month if used only periodically — but not with boiling water. Baking soda and vinegar pack a powerful cleaning punch at virtually no cost, and they are gentle enough in their approach that your Thermos will be well-protected against damage.

Pour 1-2 teaspoons of baking soda into the bottom of your pre-washed Thermos (you should already be using a bottle brush and warm soapy water to clean it after every use), add white vinegar to the bottle until it is half full, and allow the mixture to bubble. You'll want to bust out your bottle brush to scrub away any loosened film or particles from inside the bottle before rinsing it thoroughly with warm water. If your Thermos has a lid with a removable seal, straw, or other component, you can clean these pieces by putting them in a bowl and adding baking soda and vinegar so they can soak. Remember to dry the bottle and its smaller pieces completely before reassembling them and putting them back into storage.