Industry maintains drinking water quality
Posted: Thursday 28th June 2007
During 2006, the water industry maintained drinking water quality at the same overall level achieved in 2005 with 99.6 per cent of all tests meeting national and European standards.
Based on the 40 parameters used by the Drinking Water Inspectorate to describe overall compliance with drinking water standards at consumers’ taps, the changes in drinking water quality between this year and last were as follows: in Wales and also in two English regions (Eastern and Southern) the figure was the lowest at 99.95 per cent. Elsewhere in England it improved, reaching 99.98 per cent in both the Midlands and Thames regions. There was a smaller rise in the figure for the Western region, which now stands at 99.96 per cent. The position in the Northern region was unchanged and remained the lowest at 99.94 per cent.
While the report points out that the water quality results are not wholly within the control of water companies to deliver (for example, some parameters are influenced by the nature and condition of water systems within buildings), it does stress that, for parameters that are for the water industry alone to control properly (the vast majority), results have been mixed.
For example, most companies exhibited excellent results for the control of disinfection by-products as measured by the trihalomethane parameter. However, companies not picking up quickly on a failure in the supply chain for water treatment chemicals caused an increased number of failures of the bromate standard.
Areas of concern highlighted in the DWI report “Drinking Water in England and Wales” include:
the quality of treated water leaving works and service reservoirs was marginally worse than 2005;
four companies showed a deteriorating position in terms of turbidity monitoring - the DWi states that it is ‘inexcusable’ when a company’s sampling arrangements are so defective as to generate unrepresentative results;
the microbiological quality of water leaving service reservoirs declined in 2006, with more samples containing coliform bacteria and E.coli;
Professor Colbourne, Chief Inspector of Drinking Water, commented: “When fully investigated, most microbiological failures were seen to have signalled the existence of a, hitherto, undetected structural defect. The overall picture leads the Inspectorate to question whether the industry’s approach towards maintenance of these assets has become reactive and failure driven.”
To support this claim, Professor Colbourne highlighted the worst case, where, after multiple detections of E.coli, Yorkshire Water inspected inside the service reservoir and found the decomposing carcass of a rodent on the floor.
Professor Colbourne also called for an improvement in the setting of, and adherence to, critical control measures for water quality risk management, saying that it is a recurring theme that water industry staff fail to respond adequately to alarms, alerts or consumer reports. On a more positive note, the report notes that the industry delivered the year’s drinking water quality investment plans, with 70 out of 80 programmes of work being completed on time, with a further four schemes scheduled for delivery in 2007 being completed early.
Responding to publication of the report, a spokesperson for Water UK said: “The report demonstrates that the quality of tap water in England and Wales is one of the highest in the world. Consumers can confidently turn on their tap and get a safe supply of healthy, refreshing water. Where quality falls short, the report shows that consumers can be assured that mechanisms are in place to remedy problems.”
