UK legal limit
0 per 100ml
WHO guideline
0 per 100ml
EU standard
0 per 100ml
Primary sources
Sewage, animal waste
E. coli in UK drinking water is regulated at 0 per 100ml. The WHO guideline is 0 per 100ml and the EU standard is 0 per 100ml. UK regulations require zero E. coli in treated drinking water. Any detection triggers immediate investigation by the water company and the Drinking Water Inspectorate.
While most E. coli strains are harmless, some produce toxins that can cause severe illness. E. coli O157:H7, the most dangerous strain, can cause bloody diarrhoea, kidney failure (haemolytic uraemic syndrome), and in rare cases death — particularly in children and elderly people. Any detection in treated water is treated as a serious public health event.
E. coli reaches water sources through sewage discharges, agricultural runoff carrying animal waste, and combined sewer overflows during heavy rainfall. In treated water, detection usually indicates a failure in the treatment or distribution system — such as a broken pipe, cross-contamination, or a treatment plant malfunction.
| Jurisdiction | Limit / Guideline | Notes |
|---|---|---|
| UK (DWI) | 0 per 100ml | Regulated under the Water Supply (Water Quality) Regulations 2016 |
| WHO | 0 per 100ml | World Health Organization Guidelines for Drinking-water Quality |
| EU | 0 per 100ml | EU Drinking Water Directive (2020/2184). The UK no longer automatically mirrors EU standards post-Brexit. |
UV disinfection
Ultraviolet light at 254nm wavelength damages the DNA of bacteria and viruses, preventing them from reproducing. Highly effective against microorganisms without adding chemicals to the water.
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.
Chlorination
Adding chlorine or chloramine to water kills bacteria and viruses. The standard disinfection method used by UK water companies. Effective against E. coli and most waterborne pathogens.
No filter we list names e. coli specifically. Reverse osmosis is shown because it rejects dissolved contaminants broadly rather than by name. Check your own report before buying.
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.
Waterdrop 10UA Under Sink
Under-Sink Filter · NSF/ANSI 42
Typical price
£70approx.
Affiliate link: we may earn a commission at no extra cost to you.
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