The boil or sterilise advice from the Health & Social Welfare Directorate remains in place for water consumers at Ruperts Valley, 4 days after being announced on Thursday 6 September. Low levels of e-coli contamination was detected during routine water sampling last week.
Martin Squibbs, Head of the Water Division, is responsible for the water supply on the island. I asked how often does the water supply get checked? “We check the water supply every week. We take six samples around the island in the water mains so we don’t check the water quality at people’s taps, that’s the function of Public Health. We look at the water that we treat, where we treat water and distribute so we are only checking on the treated water. We check the chlorine level and also any contamination.”
Is that water in the water tanks or in the reservoirs? “It’s in the water tanks,” replied Squibbs. “We treat water at our four water works and we put that water into what we call contact tanks which are big tanks situated at the treatment works site and they allow the chlorine to mix with the water. It takes about four hours of contact time for the chlorine to make sure there is no bacteria in the water and it is properly disinfected.”
How does e-coli get into the water supply? “Well e-coli is in the water supply. E-coli is neutralised and killed by chlorine. So we inject chlorine into the treated water system to kill any kind of bacteria or contamination. And it also gives residual disinfection."
The Water Division operates within the World Health Organisation guidelines that has an upper limit of 5 milligrams of chlorine per litre of water. In hot climates and when water is stored for long periods the chlorine dissipates, evaporates and neutralises. “We have quite a bit of storage capacity on the island now of treated water and what sometimes happens is that water stays in storage for too long,” said Squibbs. “The consumer doesn’t use the water as quickly as we planned and therefore the chlorine reduces and becomes less potent in terms of bacteria kill.”
Could this be one of the causes for contamination at Ruperts because it is a small community? “Yes, I think it is,” he replied, “our analysis shows that because the Argos Fisheries aren’t processing fish just now then the use of water in Ruperts Valley isn’t as high as it normally is. So because of that low usage we think that is contributing to the lower levels of chlorine in the area.”
We’ve had issues this year about contamination of E-coli in the water system. It appears to be a recent issue that has risen. Is this due to an actual problem or is it that detection methods have improved? “No the detection methods are exactly the same. We take samples every week, we analyse the samples at the public health laboratory which is an accredited laboratory. So there’s no question that they don’t take samples properly and give proper readings. What it’s shown is there are low levels of chlorine in the Ruperts Valley area, and there is evidence of contamination at the sampling points that we’ve used and the Public Health have used. So we need to take action and we are taking action to resolve that,” concluded Squibbs.
The water tanks at Chubb’s Spring treatment works that supply Ruperts Valley have been cleaned and the efficiency of the water filters has been checked. The Health Department will issue further updates on water samples as they become available.