There were only two failures out of almost 3,500 tests of the quality of the public water supply in Dundee last year, the industry watchdog has revealed.
The Drinking Water Quality Regulator for Scotland (DWQR), which is responsible for overseeing Scottish Water’s work in sourcing, treating and distributing supplies to consumers, has published data for 2012 showing 3,491 water samples were taken in the city.
These were often from household taps to check for the presence of potentially harmful bacteria such as E coli and metals such as iron, lead and manganese. Only one of the 144 samples checked for coliform bacteria failed.
The DWQR said: “They are common in the environment and do not necessarily indicate faecal contamination, but should not be present in the water supply as they are readily deactivated by chlorine, which is added in controlled amounts to all of Scottish Water’s supplies.
“The greatest risk to public health is associated with the consumption of drinking water that is contaminated with faecal material.
“Many raw water sources contain significant levels of bacteria, which serves to demonstrate the importance of adequate treatment, especially disinfection, in order to ensure our water is safe to drink.”
The failed Dundee sample was among 61 found across Scotland during 2012.
“Scottish Water has increased its efforts in investigating failures at consumers’ taps during the past year and this improved understanding of the root causes of microbiological failures needs to result in proactive action to reduce the number of samples containing coliforms,” the regulator said.
There were 152 samples from the city’s water supply tested for iron, with a single failure that exceeded the limit of 200 microgrammes per litre. There are no health risks from such a failure.
The DWQR said: “The most common cause of failures of the iron standard at consumer taps is corroding cast iron water mains.”
The tests had no failures for aluminium, manganese or lead, or for E coli or chemicals called trihalomethanes. The colour, cloudiness and acidity of the test samples also met the required standards.
The overall pass rate for the water samples from the city’s public supply was 99.94%.