Worrying level of chemicals found in Ventry water supply
THE public water supply in Ventry has been found to contain worrying levels of chemicals associated with a variety of health risks, including cancer. However, work currently being carried out by Irish Water will alleviate the problem in the coming months.
Chemicals known as trihalomethanes (THMs), which are classified as ‘possibly carcinogenic’ and have also been linked to potential reproductive effects, have been found at high levels in the Ventry water supply, by comparison with other areas in West Kerry which are not similarly affected. However, the HSE says the health risks are minimal.
According to the HSE, the legal limit for THMs in drinking water in Europe is 100 microgrammes per litre. Water quality tests conducted in Ventry in September 2014 found 50 microgrammes of THMs per litre and this dropped to 34 microgrammes per litre when a second test was conducted a month later. In 2015 tests found 34 microgrammes of THMs per litre in April and 84 microgrammes in September. Irish Water’s website reports that a test conducted in Ventry last September found the level of THMs was at exactly the legal maximum. The website has no report of a second test being conducted following this startling result.
By comparison with Ventry, Dingle was found to have THMs levels of between 5 microgrammes/ litre (April) and 19 microgrammes/litre (September) last year, while Ballyferriter, Annascaul and Castlegregory all recorded 5 microgrammes/litre or less.
Kerry County Council Area Engineer Niall Ó Dónaill told The Kerryman that organic material from decaying vegetation causes a peak in THM levels in chlorinated drinking water in the autumn and that areas supplied from a surface water source – as is the case in Ventry – are most affected.
In most cases water treatment plants remove organic material from drinking water and this prevents the formation of THMs. However, it would appear that the Ventry treatment plant at Cill a’ Rith is not removing this organic material effectively, even though it was upgraded within the past 10 years.
Mr Ó Donaill was unable to comment on this, but he did say that work currently being carried out by Irish Water will lower THMs levels in Ventry’s water supply. A borehole has recently been drilled at Cill a’ Rith to tap into deeper groundwater, which is free of the risk of THMs contamination. This groundwater will be mixed with the existing supply from Mount Eagle Lake to lower THM levels or, if the borehole produces enough water, it will be used as the sole supply source for Ventry. He said the new water supply will be operational in the near future, and definitely before September when THMs levels tend to peak.
THMs are formed when organic material in water reacts with the chlorine used to purify public water supplies. The concentration of THMs in drinking water varies according to the level of organic material in the water, the amount of chlorine required to treat the water and the temperature of the water that is being treated
According to the HSE, people can be exposed to THMs by drinking contaminated water, inhaling THM vapour which evaporates from water, and even by absorbing the chemicals through the skin when showering.
However, the health authority says that while some studies suggest that very long-term exposure (35 years or more) to high levels of THMs may be linked to a slightly increased risk of some types of cancer, in particular bladder and colon cancer, the evidence is not conclusive. The HSE also says that findings regarding risks of miscarriage and low birth weight caused by THMs in drinking water are inconsistent
Temporarily raised levels of THMs in drinking water are “unlikely to result in any risk to health”, and “the potential risks from drinking untreated water far outweigh any possible risks of long-term exposure to THMs”, according to the HSE.
The health authority advises that people can lower their exposure to THMs in drinking water by boiling the water for one minute to allow THMs evaporate and allowing it to cool before drinking, to store tap water in the fridge for 24 hours in an open jug or to use suitable activated carbon water filters. They also recommend ensuring bathrooms and kitchens are well ventilated, taking short baths instead of a shower and using colder water to bath or shower.