Teagasc experts in water pollution breakthrough
Their new findings on Escherichia coli, a common soil bacterium, also raise doubts about EU drinking water standards.
E coli is used internationally as an indicator that a drinking water supply has become contaminated with human or animal waste, or that the disinfection system is not operating adequately.
Detection of E coli in drinking water is a breach of EU drinking water standards.
Wherever it is found the water services authority is obliged to consult with the HSE to determine whether the supply of water constitutes a potential danger to human health.
However, research by Teagasc scientists at the Johnstown Castle Environment Research Centre and NUI Galway has shown that E coli can become integrated into soil microbes and survive for more than nine years – considerably longer than scientists initially thought.
“This has important implications for the indicator status of E coli, suggesting that the presence of E coli in surface or ground waters may not be indicative of recent faecal contamination,” said researcher Fiona Brennan, in the latest edition of Teagasc’s TResearch magazine.
It has long been thought that E coli can survive only for short periods in the environment – hence its almost universal use as an indicator of recent faecal contamination of waterways. “E coli’s ability to survive for prolonged periods of time in soil may compromise its use as the sole indicator of faecal contamination of water,” said the Teagasc experts.
In contrast, an EPA drinking water advice note issued last November said: “The most important indicators of drinking water quality in Ireland are the microbiological parameters and, in particular, E coli. E coli is present in very high numbers in human or animal faeces and is rarely found in the absence of faecal pollution. As such its presence in drinking water is a good indication that either the source of the water has become contaminated or the treatment process at the water treatment plant is not operating adequately. E coli is often not in itself a harmful organism but indicates that harmful organisms may be present.”
