Mercury in Wastewater

Sources of Mercury

Sources of mercury in wastewater include:
  • Industry
  • Dental offices
  • Household products


The City of San Mateo Wastewater Treatment Plant (WWTP) operates under a municipal wastewater discharge permit that limits how much mercury and other pollutants can be discharged to San Francisco Bay. Beneficial uses of the Bay are impaired by high levels of mercury in fish, water, and sediment. It is imperative we all work towards preventing sources of mercury from coming in contact with our wastewater and stormwater.

Industrial and dental office sources are managed by Best Management Practices. Residents need to pay attention to how we dispose of certain household products. Household products that contain mercury include electronic wastes, fluorescent tubes/lights, and old thermometers and thermostats.

Electronic waste, consisting of discarded computers, televisions, cell phones, fax machines, stereos, and other electronic equipment cannot be put in landfills because of their heavy metal content. Computers under five years old and other working electronics can generally be reused, while older computers and broken electronics are generally recycled. For help in finding the proper location for drop-off of your E-waste visit RecycleWorks.

Fluorescent lights save electricity and are a good choice for energy conservation. However, they do contain small amounts of mercury sealed within the glass tubing, making the lights toxic and banned from being put in the trash. More information of the proper handling and disposal of fluorescent tubes/lights is found on the fluorescent lights webpage.