What harmful chemicals and particles are in your tap water?

What's in your water

Tap water picks up contaminants at every stage of the supply chain, from the source to the pipes in your walls. Testing reveals microplastics, PFAS (forever chemicals), lead, and disinfection byproducts in water supplies across the country. You won't see, smell, or taste most of them.

Each contaminant comes from a different source. Microplastics enter through industrial runoff. PFAS come from firefighting foam and manufacturing sites. Lead leaches from aging pipes. Disinfection byproducts form when chlorine reacts with organic matter during water treatment.

What the research says

A 2026 study traced plastic particles through an entire drinking water supply chain in Milan, Italy. Researchers found microplastics at every stage, from the aquifer to the tap. A separate study tracking a water system near industrial facilities confirmed microplastic contamination and flagged it as a potential health risk.

An investigation of a PFAS spill in McKeesport, Pennsylvania showed that a single firefighting foam accident contaminated the public water supply with per- and polyfluoroalkyl substances, chemicals linked to cancer, thyroid disease, and immune problems.

A U.S. study found that lead in drinking water was associated with increased head and neck cancer risk. Another large study in Spain linked long-term trihalomethane exposure from tap water to higher colorectal cancer risk.

How to reduce your exposure

Install a water filter certified to remove PFAS, lead, and microplastics. Reverse osmosis filters are the most thorough. Activated carbon filters handle many contaminants but miss some PFAS types. Run the tap for 30 seconds before drinking to flush lead from pipes. Test your water annually if your home has older plumbing.