In Keurig's own words, using the rinse pods is only to "reduce flavor carry-over between brews." It's not a mysterious brew of chemicals either, just maltodextrin, sodium bicarbonate, citric acid ...

Making a good cup of coffee really comes down to the beans, and if you have a pod-style coffee maker ... your consumption of one-use plastics. Turn your Keurig or other single-cup coffee maker ...

The Keurig K-Duo makes 6-, 8-, 10- and 12-ounce single servings of pod coffee or a 12-cup glass carafe of any ground coffee you have on hand via its brew basket. It has a hefty 72-ounce water ...