Detecting viruses in drinking water

DR WENDY WILLIAMSON
In general, the virus detection work that the water group is doing is to support Ministry of Health making standards for safe drinking water. As the quality of water improves in many, many countries through good treatment and good standards being used, that there are occasions now where water has passed the bacterial standards, is still making people sick in some cases, and it has been found that that water has viruses in it, and it’s those viruses that are making people sick. So therefore, it has become obvious that we need some degree of virus monitoring within the standards. So our work is to help provide the Ministry of Health with the scientific rigour to produce those standards, and we are doing that mainly by having a look at the viral load in the rivers around New Zealand that provide our source of drinking water for different communities. And we do that by taking samples of water regularly, so we take them every two to three weeks at the moment, and we have a look at what viruses we might find in there. We look at a suite of viruses, that is, what are most likely to be found and of health significance. One of the things that we are not yet sure – because this work is still, you know, very much in its early stages for the Ministry of Health – is whether we would ever ask water treatment plants to actually monitor viruses. My opinion is that is unlikely. It would be extraordinarily expensive, and it would take a lot of very specialist techniques to do it, which makes its impractical from a day-to-day perspective. What we are much more likely to do is try and understand the load of viruses in the source water, so we can understand the degrees of treatment that a plant must put in place in order to reduce that load down to a level that the risk involved of people drinking treated water is so greatly reduced that the likelihood of illness is almost nothing.