Borders water supply tests reveal cancer link

polluted tap water.
polluted tap water.

THREE samples of drinking water supplies in the Borders failed a test for a substance linked to cancer, according to a new report.

The information was revealed as part of an annual study on the standard of drinking water in Scotland for 2009 by the industries regulator, Colin McLaren.

Mr McLaren noted a drinking water sample supplied by Scottish Water in the Borders which failed a test for trihalomethanes (THMs), which has been linked to increased risk of cancer and damage to vital organs and the central nervous system. And among the region’s 1,455 private supplies, there were 194 fails, notably two for THMs, which Mr McLaren described as a “poor” result.

For a second year in a row, there was a rise in the number of THMs fails across Scotland, described as “striking” by Mr McLaren, who died last month of prostate cancer.

He said: “The percentage of THMs failures in 2009 was higher than that for every year since 2005, with more than one in 20 samples not meeting the standard.

“This is disappointing and surprising given the investment in treatment processes that has brought about an improvement in compliance for other parameters such as hydrogen, iron and colour.”

Among the 194 fails in private water supplies, there were 59 related to coliform bacteria, and 46 cases of unacceptable E-coli levels, which Mr McLaren suggests came from faecal contamination. Both bacterias can lead to cramps and diarrhoea.

As a result, Mr McLaren named microbiological standards of private supplies as “poor”.

However, he noted an improvement on last year’s figures when more than half of private supplies failed coliform tests and 40 per cent did not pass E-coli standards.

Mr McLaren noted: “Failure of the Total Coliforms standard does not necessarily mean that there is a risk to health; it does, however, indicate that there is no disinfection, that the disinfection is inadequate or that there has been a breach in the water supply system.”

Mr McLaren also criticised pH readings, with around 1 in 10 private samples failing. “Exceedances of the pH standard increases the risk of metals from plumbing materials dissolving into water supplies,” he wrote.

Among the nine fails recorded from 7,406 tests to Scottish Water’s supply to the Borders, there were two instances of failures for iron.

Meanwhile, Roberton water treatment works near Hawick was singled out after recording a raw water sample with the highest level of cryptosporidium in Scotland, and also being one of only three works to fail a nitrite sample test. Nitrite in water can present dangers to the health of infants, while cryptosporidium can led to diarrhoea and vomiting.

But Mr McLaren added: “Roberton was an effective treatment process which means that this does not represent the situation in the final water. An appropriate, well-optimised treatment process should minimise the risk of cryptosporidium oocysts being present in the final water.”

Roberton was also one of Borders’ two treatment works to record incidents affecting drinking water quality in 2009. Levels of aluminium in its water exceed the maximum allowed in October 2009 at Roberton, while in November last year households supplied by Yarrowfeus’ treatment works were told to boil water after cryptosporidium was detected.

Responding to concerns surrounding THMs in drinking water, Scottish Water said 2009 levels around Scotland were within healthy parameters and that THM compliance had improved since last year.

A spokesperson said: “Across Scotland water quality is at an all-time high.

“We work closely with the drinking water quality regulator to ensure that we work to improve water quality across Scotland. Scottish water is safe to drink and poses no long-term health effects. We recognise there was a drop in 2009 from the performance in 2008, and we are taking positive steps to address this.”