Lead, Nitrate and Chlorine: A Practical Guide to Tap Water Contaminants
A clear overview of the most common drinking water contaminants in Europe and North America, the health effects, and the right filter for each.
Tap water in most developed countries is tightly regulated, yet specific contaminants still show up in measurable amounts. Here is what to watch for, why it matters, and which technology actually addresses each issue.
Chlorine and chloramines
Used by utilities to disinfect water. Safe at regulated levels, but cause a noticeable taste and odour and can react with organic matter to form disinfection by-products. Activated carbon filters remove chlorine reliably.
Lead
Mostly originates from old lead service lines and brass fittings. Especially risky for infants and pregnant women because lead damages neural development. NSF/ANSI 53 certified carbon block filters with explicit lead reduction or reverse osmosis are effective.
Nitrate
Comes from agricultural runoff and fertilisers. High nitrate is dangerous for bottle-fed infants (methaemoglobinaemia). Standard carbon filters do not remove nitrate. Use reverse osmosis or ion exchange.
Pesticides and pharmaceutical residues
Trace amounts of glyphosate, atrazine and various drug residues appear in many surface waters. Good activated carbon block filters and reverse osmosis both reduce them.
Microbiological contamination
E. coli, coliforms, Legionella in stagnant pipes. Carbon filters do not help. Boiling, ultrafiltration (less than 0.1 micron) or UV disinfection do.
Microplastics
Filters with pore sizes below 1 micron, including most reverse osmosis systems and dense ultrafilters, capture the bulk of detectable microplastics.
How to find out what is in your water
Most European utilities publish annual water quality reports. In the United States the EWG Tap Water Database is a useful starting point. For private wells, an accredited laboratory test is essential at least once a year.