If you make your morning cup of joe in a pod-based espresso maker, you might be brewing more than coffee. A recent study by researchers at the University of Valencia has found that the drip trays that catch run-off liquid in coffee makers are often host to a pretty wide range of weird bacteria. 

The researchers observed ten Nespresso brand espresso machines, monitoring bacterial growth over the course of two months. They found that, although caffeine usually has antibacterial properties, several strains of caffeine-resistant bacteria started to develop in the drip trays of the machines.

“They found that nine of the ten machines harbored residues rich in Enterococcus bacteria, a typical marker of human fecal contamination,” Scientific American notes. “And another common resident was Pseudomonas—which has both benign and pathogenic strains.”

Pseudomonas isn’t just resistant to caffeine—it can actually break it down. That means, it may serve a purpose beyond reminding us how gross our coffee makers are: Eventually, when scientists learn more about it, pseudomonas “might be put to work decaffeinating coffee, or cleaning caffeine residues from our waterways,” Scientific American explains

While these findings may be unsettling, they don’t mean the coffee we’re drinking is contaminated. The study noted that bacteria was discovered in the drip tray, but not in the Nespresso pods themselves—which means our coffee is safe, though it might be a good idea to clean out the drip tray every once in a while.

[h/t: Scientific American]