Annex B – Compliance with standards

Parameter	Standard	Total number of tests	Number of tests not meeting the standard	Number of tests not meeting the standard per company	Percent compliance (3dp)
Clostridium Perfringens (sulphite-reducing clostridia) (confirmed)	0 number/100 ml	604	–		100%
Turbidity – indicator	1 NTU	11,940	1	HDC (1)	99.992%
E. coli (confirmed)	0 number/100 ml	11,943	–		100%
Total coliforms (confirmed)	0 number/100 ml	11,943	3	DWR(3)	99.975%
Total		36,430	4

Table 22 – Microbiological compliance at water treatment works

Parameter	Standard	Total number of tests	Number of tests not meeting the standard	Number of tests not meeting the standard per company	Percent compliance
E. coli (confirmed)	0 number/100 ml	19,462	2	DWR(2)	99.99%
Total coliforms (confirmed)	0 number/100 ml	19.462	18	DWR(17) HDC(1)	99.91%
Total		38,924	20

Table 23 – 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	Percent compliance
Coliform bacteria (indicator)	0 number/100 ml	8,871	33	HDC(9) DWR(24)	99.628%
E. coli (confirmed)	0 number/100 ml	8,871	2	DWR(1)	99.977%
Enterococci (confirmed)	0 number/100 ml	751	0
Total		18,493	35

Table 24 – Microbiological compliance at consumers’ taps (water supply zones)

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 – 12
DWR	0 – 10,990	2 – 15,747	1 – 8223	3 – 34,960
HDC	0- 953	0 – 3,715	1 – 636	1 – 5,304

Table 25 – Detection of E. coli and Enterococci at treatment works, service reservoirs and consumers’ taps, by company

Chemical parameters

Parameter name	Standard	Total number of tests	Tests not meeting the standard	Tests not meeting the standard per company
1,2-Dichloroethane	3 µg/L	468
Aluminium	200 µg/L Al	3,188
Ammonium (zone)	0.5 mg/L NH₄	929
Antimony	5 µg/L Sb	749
Arsenic	10 µg/L As	749
Benzene	1 µg/L	468
Benzo[a]Pyrene (total)	0.01 µg/L	754
Boron	1 mg/L B	458
Bromate	10 µg/L BrO₃	581
Cadmium	5 µg/L Cd	749
Chromium	50 µg/L Cr	749
Colour	20 mg/L Pt/Co	3,225	1	HDC(1)
Copper	2 mg/L Cu	749
Cyanide	50 µg/L CN	459
Electrical conductivity	2500 µS/cm at 20°C	2,997
Fluoride	1.5 mg/L F	460
Gross alpha	0.1 Bq/L	1
Gross beta	1 Bq/L	1
Hydrogen ion (pH) – zone	6.5 – 9.5 pH Value	3,220
Iron	200 µg/L Fe	3,188	17	HDC(2), DWR(16)
Lead	10 µg/L Pb	747	2	DWR(2)
Manganese	50 µg/L Mn	3,190	1	DWR(1)
Mercury	1 µg/L Hg	458
Nickel	20 µg/L Ni	749
Nitrate	50 mg/L NO₃	751
Nitrite – consumers taps	0.5 mg/L NO₂	751
Odour	Acceptable to consumers and no abnormal change	3,222	5	DWR(5)
Pesticides (total by calculation)	0.5 µg/L	725
Polycyclic aromatic hydrocarbons (total by calculation)	0.1 µg/L	752
Residual disinfectant – free	2 mg/L	8,897
Residual disinfectant – total	2 mg/L	8,261
Selenium	10 µg/L Se	749
Sodium	200 mg/L Na	749
Sulphate	250 mg/L SO₄	460
Taste (quantitative)	Acceptable to consumers and no abnormal change	3,220	5	DWR(5)
Tetrachloromethane	3 µg/L	466
Trichloroethene & Tetrachloroethene – sum of 2 substances	10 µg/L	464
Trihalomethanes (total by calculation)	100 µg/L	754
Tritium	100 Bq/L	1
Total		58,956	30

Table 26 – chemical parameter sample numbers and number of failures

Parameter name	Standard	Total samples	Total failures	Detected pesticides
Individual Pesticides	0.1 µg/L	9,275	0	0

Table 27 – individual pesticide sample numbers and number of failures