Thermometers Hazardous Waste Illegal in Garbage or Drains Contains Mercury Find out what to do with hazardous waste How to Check for Mercury A silver, metallic liquid will be visible from inside the bulb or vial if the thermometer contains mercury. Digital Thermometers Are E-Waste Remove batteries and dispose of them as household hazardous waste. Next recycle digital thermometers as e-waste, because they contain small electronic parts. Ways to Reduce Don't Purchase Mercury If you avoid purchasing mercury, you can reduce the amount that is available to leach into lakes and rivers. Did You Know? Mercury-Free Medical Devices Only Healthcare facilities contributed the most amount of mercury to the environment in the US and Europe decades ago. Once they realized the dangers of mercury exposure, they phased out the use of medical devices containing mercury.