- Drinking Water 2024 – Summary of the Chief Inspector’s report for drinking water in Wales
- Foreword
- Water supplies and testing
- Compliance with standards
- Learning from compliance failures
- Learning from events
- Consumer contacts
- Asset health
- Water safety planning and risk assessment
- Raw water
- Poly and perfluoroalkyl substances (PFAS)
- Audit programme
- Recommendations
- Enforcement
- SEMD
- NIS
- Materials in contact with drinking water (Regulation 31)
- Research publications
- Whistleblowers
- Working with stakeholders
- Annex A – Number of tests carried out by companies
- Annex B – Compliance with standards
- Annex C – Compliance failures and events
Annex B – Compliance with standards
Microbiological compliance at water treatment works
| Parameter | Current standard | Total number of Tests | Number of tests not meeting the standard | Number of tests not meeting the standard per company |
|---|---|---|---|---|
Clostridium Perfringens (sulphite-reducing clostridia) | number/100 mL | 600 | 0 | |
| E. coli | number/100 mL | 12,108 | 0 | |
| Turbidity – indicator | NTU | 12,093 | 0 | |
| Total coliforms | number/100 mL | 12,108 | 2 | DWR(2) |
Microbiological compliance at service reservoirs
| Parameter | Standard | Total number of tests | Number of tests not meeting the standard | Number of tests not meeting the standard per company |
|---|---|---|---|---|
| E. coli | 0 number/100 mL | 20,057 | 0 | |
| Total coliforms | 0 number/100 mL | 20,057 | 12 | DWR(10) HDC(2) |
Microbiological compliance at consumers’ taps (water supply zones)
| Parameter | Standard | Total number of tests | Number of tests not meeting the standard | Number of tests not meeting the standard per company |
|---|---|---|---|---|
| Coliform bacteria (indicator) | 0 number/100 mL | 8,703 | 30 | DWR(26) HDC(4) |
| E. coli | 0 number/100 mL | 8,703 | 1 | DWR(1) |
| Enterococci | 0 number/100 mL | 753 | 0 |
Detection of E. coli and Enterococci at treatment works, service reservoirs and consumers’ taps, by company
| Company | E. coli in water leaving treatment works | E. coli in water leaving service reservoirs | E. coli at consumers’ taps | Enterococci at consumers’ taps |
|---|---|---|---|---|
| ALE | 0 – 0 | 0 – 0 | 0 – 12 | 0 – 4 |
| DWR | 0 – 11,166 | 0 – 16,189 | 1 – 8,067 | 0 – 638 |
| HDC | 0 – 942 | 0 – 3868 | 0 – 624 | 0 – 111 |
Chemical parameters
| Parameter name | Number of tests | Number of tests not meeting the standard | Number of tests not meeting the standard per company |
|---|---|---|---|
| 1,2-Dichloroethane (total) | 466 | 0 | |
| Aluminium (total) | 3,152 | 0 | |
| Ammonium (zone) | 921 | 0 | |
| Antimony | 755 | 0 | |
| Arsenic (total) | 755 | 0 | |
| Benzene (total) | 466 | 0 | |
| Benzo[a]Pyrene (total) | 761 | 0 | |
| Boron | 455 | 0 | |
| Bromate | 583 | 0 | |
| Cadmium (total) | 754 | 0 | |
| Chromium (total) | 755 | 0 | |
| Colour | 3,187 | 1 | HDC(1) |
| Copper (total) | 755 | 0 | |
| Cyanide (total) | 462 | 0 | |
| Electrical conductivity | 2,959 | 0 | |
| Fluoride (total) | 462 | 0 | |
| Gross alpha | 1 | 0 | |
| Gross beta | 1 | 0 | |
| Hydrogen ion (pH) – indicator – zone | 3,186 | 0 | |
| Iron (total) | 3,155 | 13 | HDC(1) DWR(12) |
| Lead (10) | 755 | 1 | DWR(1) |
| Manganese (total) | 3,156 | 1 | DWR(1) |
| Mercury (total) | 465 | 0 | |
| Nickel (total) | 755 | 2 | DWR(1) HDC(1) |
| Nitrate (total) | 756 | 0 | |
| Nitrite – consumers taps | 755 | 0 | |
| Odour | 3,183 | 4 | HDC(1) DWR(3) |
| Pesticides (total by calculation) | 704 | 0 | |
| Polycyclic aromatic hydrocarbons (total by calculation) | 727 | 0 | |
| Residual disinfectant – free | 8,746 | 0 | |
| Residual disinfectant – total | 8,121 | 0 | |
| Selenium (total) | 755 | 0 | |
| Sodium (total) | 755 | 0 | |
| Sulphate | 462 | 0 | |
| Taste (quantitative) | 3,183 | 8 | DWR(7) HDC(1) |
| Tetrachloromethane (total) | 464 | 0 | |
| Trichloroethene & Tetrachloroethene – sum of 2 substances (total by calculation) | 465 | 0 | |
| Trihalomethanes (total by calculation) | 757 | 0 | |
| Tritium | 1 | 0 |
Pesticide parameters
| Parameter name | Standard | Total samples | Total failures | Detected pesticides |
|---|---|---|---|---|
| Individual Pesticides | 0.1 µg/L | 9,243 | 0 | |
| Total | 9,243 | 0 |