Health Effects of Tap Water Contaminants

Chlorine is added intentionally as a disinfectant and is generally safe at regulated levels. The taste and smell concern most people, not acute health risk. However, chlorine reacts with organic matter to form disinfection byproducts (DBPs) such as trihalomethanes (THMs), which are classified as possible human carcinogens. Long-term exposure to high THM levels has been associated with increased bladder cancer risk in some epidemiological studies.

Sources: WHO Chlorine Guidelines ↗ · EEA ↗

The WHO states there is no known safe level of lead exposure. Lead enters drinking water primarily from old lead service pipes and leaded solder in home plumbing — a problem in pre-1970s buildings across Southern Europe. Children and pregnant women face the greatest risk. Effects include cognitive impairment, developmental delays, and cardiovascular damage. The EU revised its lead limit from 10 µg/L to 5 µg/L in 2021, but older plumbing often exceeds this.

Sources: WHO Lead Fact Sheet ↗ · EU Drinking Water Directive 2020/2184

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals that persist in the environment and human body. Linked in research to thyroid disruption, immune suppression, certain cancers, and developmental effects in children. A 2023 EEA study found PFAS above health advisory levels in drinking water sources across 17 EU countries. Standard carbon filters do not remove PFAS — reverse osmosis or specialised activated carbon is required.

Sources: EEA PFAS Report ↗ · EFSA ↗

Microplastics have been detected in tap water, bottled water, and virtually all global water sources. A 2019 WHO review concluded current evidence is insufficient to determine health risk, but called for further research. More recent studies have found microplastics in human blood and lung tissue. The EU has added microplastics monitoring requirements to its 2021 Drinking Water Directive. Hollow-fiber ultrafiltration and some ceramic filters can remove microplastics.

Sources: WHO Microplastics Report 2019 ↗

Nitrates leach into groundwater from agricultural fertilisers and are a known concern in rural southern Spain, Portugal, and parts of Greece. High nitrate levels (above 50 mg/L) cause methemoglobinemia ("blue baby syndrome") in infants under 6 months. For adults, long-term exposure above guidelines has been associated with colorectal cancer in observational studies. Standard carbon filters do not remove nitrates — ion exchange or reverse osmosis is required.

Sources: EU Nitrates Directive ↗

Water hardness — caused by dissolved calcium and magnesium — is not a health concern and is associated with reduced cardiovascular risk in some studies. The practical problems are limescale damage to appliances, dry skin, and flat-tasting coffee. Southern European water is typically very hard (200–500 mg/L CaCO₃). Softeners reduce hardness but increase sodium content — not ideal for people on low-sodium diets. Most filter tests score hardness reduction as a secondary metric.

Sources: WHO Hardness Guidelines ↗

Copper piping is common in European buildings from the 1970s–1990s. Slightly acidic water (common in mountain-source supplies) corrodes copper pipes, releasing copper ions. While copper is an essential trace mineral, excess intake causes nausea, vomiting, and liver damage over time. The EU limit is 2 mg/L. Corrosion risk is highest in first-flush water after pipes sit idle overnight.

Sources: EU Drinking Water Directive 2020/2184 · WHO Guidelines for Drinking-water Quality

Municipal water treatment in the EU reliably removes bacterial pathogens. Risk increases in rural areas with private wells, areas affected by flooding, and very old distribution infrastructure. Immunocompromised individuals, elderly people, and infants face higher risk. UV filters and 0.2-micron ceramic/hollow-fiber filters provide an additional barrier without altering water chemistry.

Sources: ECDC Water-borne Disease Reports ↗

✅ Chlorine, chloramines, VOCs, some pesticides
✅ Taste and odour improvement
❌ Does not remove heavy metals, PFAS, nitrates, bacteria

✅ PFAS, heavy metals, nitrates, microplastics
✅ Bacteria, viruses, dissolved solids
❌ Removes beneficial minerals too · Slow · Produces wastewater

✅ Bacteria, viruses, protozoa
❌ Does not remove chemical contaminants, heavy metals, or PFAS
⚠️ Best used as a final stage after particle filtration

✅ Sediment, bacteria, cysts, microplastics (0.2µm)
❌ Does not remove dissolved chemicals, chlorine, heavy metals
✅ Long filter life · No wastewater