UK Legal Limit
5 mg/L (residual)
WHO Guideline
5 mg/L
EU Standard
No specific limit
Primary Sources
Added as disinfectant
Chlorine in UK drinking water is regulated at 5 mg/L (residual). The WHO guideline is 5 mg/L and the EU standard is No specific limit. Chlorine is deliberately added to UK tap water as a disinfectant. At the levels used (typically 0.2-0.5 mg/L), it is not harmful to health.
At the levels used in UK drinking water (typically 0.2-0.5 mg/L), chlorine is not harmful to health. However, chlorine reacts with organic matter in water to form disinfection byproducts (DBPs), including trihalomethanes, which are linked to health risks at elevated levels. Some people find the taste and smell of chlorinated water unpleasant.
Chlorine is added at water treatment works as the final step before distribution. UK water companies use either free chlorine or chloramine (combined chlorine) to maintain disinfection throughout the pipe network. The level is highest at the treatment works and decreases as water travels through the distribution system.
| Jurisdiction | Limit / Guideline | Notes |
|---|---|---|
| UK (DWI) | 5 mg/L (residual) | Regulated under the Water Supply (Water Quality) Regulations 2016 |
| WHO | 5 mg/L | World Health Organization Guidelines for Drinking-water Quality |
| EU | No specific limit | EU Drinking Water Directive (2020/2184). The UK no longer automatically mirrors EU standards post-Brexit. |
Activated carbon
Porous carbon material (from charcoal or coconut shell) that adsorbs contaminants as water passes through. Best for organic compounds and some heavy metals.
Carbon block filters
Dense blocks of activated carbon that physically block particles and adsorb chemicals. More effective than granular carbon for lead and other heavy metals.
Reverse osmosis
A membrane filtration process that removes up to 99% of contaminants by forcing water through a semi-permeable membrane under pressure. Highly effective but produces some wastewater.
These list chlorine among what they reduce. Check your own report first — a filter is only worth buying for a contaminant your supply actually has.
Listed to reduce Chlorine
Doulton HIP Ultracarb
Under-Sink Filter · NSF/ANSI 42, NSF/ANSI 53
Typical price
£120approx.
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Listed to reduce Chlorine
Waterdrop G3P600 Reverse Osmosis
Reverse Osmosis · NSF/ANSI 58, NSF/ANSI 372
Typical price
£550approx.
Affiliate link: we may earn a commission at no extra cost to you.
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