If you’re a regular at your local organic coffee shop, here’s a great way to reduce your impact on the environment: Bring your own mug.

As environmental activists Kim McKay and Jenny Bonnin state in their excellent resource book, True Green: 100 Everyday Ways you Can Contribute to a Healthier Planet, it’s time to dispense with the disposables.

“Life-cycle analysis of the energy and waste from producing, transporting and disposing of cardboard or polystyrene cups shows the ceramic mug to be far more eco-efficient—even taking into account the water needed to wash it between uses,” note the authors, the forces behind Clean Up the World.

A ceramic mug, on the other hand, can be used some 3,000 times, they note, creating “30 times less solid waste and 60 times less air pollution than using the equivalent number of cardboard cups.”

Baristas seldom object to serving you in your own mug, McKay and Bonnin say. After all, their establishments save money, too!