You may already know your computer keyboard and mouse can be incredibly germy items, but you may be surprised what a new study says is probably the dirtiest place in your office.

Kimberly-Clark Professional recently swabbed almost 5,000 surfaces in office buildings and then ran those swabs through a device that measures ATP, the energy molecule found in all animal, plant, bacteria, yeast and mold cells.

Keyboards did make the “dirtiest” list, but it was actually the faucet handles on break room sinks that took the dubious top honors. In fact, four out of the five worst offenders were found in break rooms, where you’ve probably eaten your lunch at least once.

The researchers were quick to point out that “dirty” doesn’t necessarily equal “germy,” but since dirty surfaces do provide a breeding ground for bacteria, it might be time to hire a cleaning crew.

Charles Gerba, PhD, of the University of Arizona, said, “People are aware of the risk of germs in the restroom, but areas like break rooms have not received the same degree of attention. This study demonstrates that contamination can be spread … when office workers heat up lunch, make coffee, or simply type on their keyboards.”

The five dirtiest workplace items

1. Break room sink-faucet handles
2. Microwave door handles
3. Keyboards
4. Refrigerator door handles
5. Water fountain buttons