IDEXX, the global leader in rapid microbiological testing for water, has announced that South West Water has selected the Colilert-18 method to detect the presence of E. coli and coliforms in its drinking water.
The switch to Colilert-18 from the traditional agar plate method followed a six-month comparison study between the two. The study concluded that Colilert-18 was faster, more accurate and met the goals of the laboratory and operational scientists.
South West Water supplies a customer base of 1.7 million people throughout Cornwall and Devon and in small areas of Dorset and Somerset, and welcomes more than 7.0 million visitors during the peak summer tourism months.
Accurate and timely microbiological analysis is essential in delivering their goal of supplying good, safe drinking water that has the trust of their consumers.
South West Water is the latest major UK utility to adopt the Colilert-18 test, which is also used extensively by Thames Water, South East Water and Essex & Suffolk Water.
Providing confirmed results in 18 hours compared to the 48 hours it takes to run agar based tests and requiring no confirmation steps, Colilert-18 was made the ISO 9308-2 standard for the enumeration of E. coli and coliform bacteria in all types of water in 2012 and was added to the European Drinking Water Directive in 2015, where it is now included as one of only two reference methods for coliform and E. coli detection.
Claire Coppin, South West Water’s Laboratory Manager, said: “Switching to the Coliert-18 test enables us to get water quality results in half the time compared to the agar tests that we ran previously. It is quick and simple to use and our studies showed it to be more accurate.”
Andrew Headland, Senior Business Manager for IDEXX EMEA, said, “Colilert-18 has again demonstrated real value to a water operations team, providing accurate, rapid and cost effective results which facilitate confident decision-making. The value of a long shelf life also means that South West Water will only need to order two to three batches per year compared to two to three batches per week for the agar based test.”
Colilert-18 consists of a reagent powder, which is added to a standard 100ml water sample and then incubated for 18 hours in the case of presence/absence determination.
