In its annual report, the DWQR stated in 2014 there had been a “deterioration throughout the water supply system” relating to microbiological parameters – with the indicator organisms being coliforms and E.coli – in particular for tests carried out at treatment works rather than from customers’ taps.
There were 40 failed tests for coliform during the year, and two for E.coli out of a total of 63,858 tests at water treatment works. In 2013, only 17 samples contained coliforms and one contained E. coli.
The Drinking Water Quality Regulator for Scotland Sue Petch said: “I am disappointed to have to report this position and have requested that Scottish Water examine disinfection processes, in detail, at all of its treatment works.”
However, the report shows that of 318,111 regulatory tests carried out on Scotland’s drinking water last year, 99.89 per cent met the required standard.
This figure has remained the same from 2013, with improvements on some parameters set against deterioration in others. The long-term trend shows that water quality has improved since Scottish Water was formed in 2002, when 99.28 per cent of samples were compliant.
The report adds that metal parameters – aluminium, iron and manganese – had shown “significant improvement” following Scottish Water’s recent investment in its pipe network.
This should feed through into reduced incidence of discoloured water and fewer customer complaints in future, predicted the regulator.
Petch stated: “It is satisfying to be able to report that in 2014 Scottish Water have maintained their high level of compliance, which reflects their efforts over the past year.
She added: “This by no means indicates that further improvements cannot be delivered. Work is still needed to make sure that all of Scotland’s water assets are well maintained and sufficiently resilient to deal with challenges presented by changing source water quality.”
This article first appeared on WWTonline.