Skip the NI Direct Bar
Department of the Environment logo
Northern Ireland Environment Agency logo

Quality of Water Leaving Water Treatment Works

Last updated: 29 May 2007

European Directive Standards

Parameter Prescribed Concentration
or Value		 Total Number
of Tests		 Number of Tests
Failed		 % of Tests
Failed		 Number of Works
with Failures
Nitrite (works)                   0.1 mg NO2/l 864 5 0.58 2
TOTAL   864 5 0.58  


National Standards

Parameter Prescribed Concentration
or Value		 Total Number
of Tests		 Number of Tests
Failed		 % of Tests
Failed		 Number of Works
with Failures
Coliform Bacteria              0/100ml 9,886 12 0.12 9
Escherichia Coli 0/100ml 9,886 6 0.06 6
TOTAL   19,772 18 0.09  


Additional European Monitoring Requirements

Parameter Prescribed Concentration
or Value		 Total Number
of Tests		 Number of Tests
Failed		 % of Tests
Failed		 Number of Works
with Failures
Colony counts @ 220C    No abnormal Change 9,885      
Colony counts @ 370C No abnormal Change 9,888      
Residual disinfectant
(Free chlorine mg/l)		   9,875      
Residual disinfectant
(Total chlorine mg/l)		   9,875      
Turbidity 1 NTU 9,884 153 1.55 29
TOTAL   49,407 153 0.31  


Northern Ireland Requirement

Parameter Reporting
Value		 Total Number
of Tests		 Number of Tests
> 1 oocysts/100mls		 % of Tests
Reported		 Number of Works
Reported
Cryptosporidium oocysts <1 oocysts per
10 litres		 1,495 0 0.00 5*
TOTAL   1,495 0 0.00  

*Continuous monitoring at five water treatment works assessed at being at risk, out of a total of 48 water treatment works