What Is the Level of Chlorine in UK Tap Water?
- SustainWater
- Sep 10, 2025
- 2 min read
Updated: Oct 30, 2025
What is Chlorine?
Chlorine is a chemical disinfectant widely used to prevent the spread of waterborne diseases. It is one of the most common treatment chemicals in drinking water worldwide.
What levels are found in UK water?
Chlorination was first introduced into UK drinking water in 1905 in Lincoln, after a deadly typhoid outbreak killed more than 100 people. The emergency use of chlorine eliminated the outbreak, and by the 1920s, routine chlorination became standard across the UK.
Today, UK water companies maintain chlorine at around 0.5–1.0 mg/L at treatment plants, gradually reducing to 0.1–0.8 mg/L by the time water reaches consumers’ taps. This “residual chlorine” ensures protection against bacterial regrowth in the distribution system.
Levels are carefully regulated and kept well below the WHO safe guideline of 5 mg/L. Still, variations can occur depending on local infrastructure, distance from treatment works, and seasonal adjustments (e.g., higher chlorine levels in summer when bacteria multiply faster).
What are the health effects of Chlorine?
At regulated levels, chlorine is considered safe by UK health agencies. However, concerns exist:
Short-term exposure: Some people notice taste, smell, or mild skin irritation. Those with sensitive skin conditions (eczema, psoriasis) sometimes report flare-ups.
Respiratory effects: Studies suggest that chlorinated water vapour (e.g., during showering) may irritate asthma sufferers.
Disinfection by-products (DBPs): When chlorine reacts with organic matter, it forms by-products like trihalomethanes (THMs). Research links long-term exposure to an increased risk of bladder cancer and possible reproductive issues. The EU sets THM limits at 100 µg/L.
Gut microbiome impact: Emerging research indicates that chlorinated water could subtly alter the balance of beneficial gut bacteria, though findings remain debated.
What can be done?
If taste or smell bothers you, letting tap water stand uncovered or chilling it in the fridge can help chlorine dissipate. But the only way to know the actual chlorine and DBP levels in your home is through testing.
Activated carbon filters are the most effective way of removing chlorine. Our Stainless Steel Stand filters remove 99% of Chlorine and DBP.
Conclusion: Chlorine protects public health, but its by-products and side effects raise valid concerns. Testing ensures you know whether your exposure is minimal or higher than average.
Check out our High Sensitivity Testing Kit, Accurate to 0.05ppm
Check out out Stainless Steel Stand Filter With 2x Ceramic Activated Carbon Filters
Comments