Water supply in Dun Laoghaire-Rathdown and North and East County Wicklow continues to meet regulatory standards

05 October 2022

Information below is relevant until further updates are provided here or on our Supply and Service Updates section.

Irish Water can confirm that specialist results received today following ongoing testing of the Raw Water for the drinking water in Dun Laoghaire-Rathdown, Dublin City and North and East Wicklow areas has indicated the presence of low levels of a naturally occurring substance called MIB (Methylisoborneol).

While MIB can result in some people detecting an earthy, musty smell and taste from their drinking water, it is not harmful to human health.

MIB is a naturally occurring organic substance produced by algae found in lakes, rivers, streams and reservoirs. It can be smelled at very low concentrations. Seasonal increases in naturally occurring algae or bacteria in water sources can cause a rise in MIB above the taste and odour threshold for some people. It is impossible to predict the onset of an incidence of MIB, or how long it will last. However, it will likely be resolved in the short term as the current rain spell continues and the weather cools. We will continue to keep this water supply under close review and will continue monitor for levels of MIB in the water.

According to the World Health Organisation Guidelines for Drinking-water Quality, MIB has no public health significance.

Irish Water can confirm that drinking water microbiological and chemical analysis carried out on water produced at our water treatment plants serving Dublin and Wicklow is compliant with drinking water regulations. Water produced at our treatment plants is tested daily in conjunction with extensive monitoring in the distribution network and is safe to drink.

Speaking about the detection of MIB in the drinking water, Tom Cuddy, Head of Asset Operations with Irish Water said “Our primary focus is the protection of public health and we would like to reassure customers that the water coming from the drinking water plants serving Dublin and Wicklow is safe to drink. We understand the concerns raised by some customers in relation to the smell or taste of their drinking water. While the smell and taste can be unpleasant for some customers, MIB is not toxic or harmful and the water remains safe to drink. As a precaution, we have increased testing on these supplies and are keeping the situation under close review.

Further information on MIB and drinking water quality can be found on our dedicated drinking water quality section.

Customers with queries or concerns about the quality of their drinking water should contact the Irish Water customer care helpline, open 24/7 on 1800 278 278 or via Twitter @IWCare.

Previous Updates

Irish Water wishes to advise that investigations are ongoing at Vartry Water Treatment Plant following reports from some customers in Dun Laoghaire-Rathdown, Dublin City and North County Wicklow areas of an “earthy” taste and smell in their drinking water.

Irish Water can confirm that the drinking water produced at the plant receives full chlorination and Ultra-Violet (UV) disinfection, meaning it does not contain any harmful bacteria, viruses, or protozoa.  

The water produced at the plant is tested daily in conjunction with extensive monitoring in the distribution network. However, following these reports of abnormal taste and odour, Irish Water has arranged additional sampling on top of our normal water quality sampling programme as a precaution and continues to keep the situation under close review.

Whilst our investigations are ongoing, previous investigations of this nature have identified the source water as the possible cause of an earthy taste and this can in particular be due to the growth of algae in the area where water is abstracted. This can result in an earthy or musty taste / smell in the drinking water. While the taste and smell can be unpleasant, drinking water with an earthy or musty taste is typically harmless. The taste and smell may be compounded due to changes in raw water characteristics caused by seasonal changes and reduced levels in the raw water supply as we move from Summer to Autumn.

Kevin Love, Regional Asset Operations Lead at Irish Water said, “Irish Water would like to reassure customers that public health is our number one priority and drinking water produced at the water treatment plant is fully compliant with statutory drinking water regulations and is safe to drink. The water produced at the plant is tested daily in conjunction with extensive monitoring in the distribution network and additional sampling and analysis is underway to establish the root cause of the change in taste and smell. We will continue to keep the situation under close review until normal drinking water supply is restored. We regret any inconvenience caused.”

For more information on taste and odour issues in drinking water, customers can visit the Supply and Service Updates section of our website. Information on drinking water quality can be found in our drinking water quality section.

Customers with queries or concerns about the quality of their drinking water should contact the Irish Water customer care helpline, open 24/7 on 1800 278 278 or via Twitter @IWCare.

Irish Water is responsible for the delivery of all public water and wastewater services in Ireland. We are committed to continuously upgrading and developing critical infrastructure to support the growth needed in housing and across our economy, while protecting the environment and safeguarding water supplies.

Irish Water wishes to advise that investigations are ongoing at Vartry Water Treatment Plant as some homes and businesses in Dun Laoghaire-Rathdown, Dublin City and North and East County Wicklow continue to experience some slight taste and odour issues with their water supply.

A small number of customers have been reporting earthy and musty tastes and odours from their water supply. In response, Irish Water have carried out sampling and analysis of the water supplies in these areas and can confirm that the water continues to fully meet chemical and microbiological regulatory standards and is safe to drink.

Following a major supply outage on the 9th of September reservoir levels have stabilised and reached full capacity, with network flows and pressure returning to normal operating conditions.  However, a number of customers are still reporting taste and odour issues this may be due to possible changes in raw water characteristics caused by reduced lake level and seasonal changes as we move from Summer to Autumn. Irish Water, in partnership with Dun Laoghaire-Rathdown, Dublin City Council and Wicklow County Councils, continues to investigate the reports.

Kevin Love, Regional Asset Operations Lead at Irish Water said, “We are currently investigating the source of the Taste and Odour issues and testing the water to determine the root cause. There may be a number of contributing factors and Irish Water are looking into possible changes in the raw water characteristics and lake levels that may be causing the complaints. “The water treatment plant is operating in full compliance with drinking water regulatory parameters and will automatically shut down if specific online monitoring records a value greater than regulatory operating targets safeguarding public health. We have also carried out investigative and regulatory monitoring on the supply network to ensure the water quality meets regulatory compliance parameters and all samples have returned compliant results verifying the water is safe to drink.

The Irish Water customer care helpline is open 24/7 on 1800 278 278 and customers can also contact us on Twitter with any queries or concerns. For real time updates, please visit the Supply and Service Updates section of our website. 

Irish Water is responsible for the delivery of all public water and wastewater services in Ireland. We are committed to continuously upgrading and developing critical infrastructure to support the growth needed in housing and across our economy, while protecting the environment and safeguarding water supplies.

Irish Water wishes to advise that some homes and businesses in Dun Laoghaire-Rathdown and North and East County Wicklow may continue to experience some slight taste and odour issues with their water supply as the network returns to normal following a recent supply interruption at Vartry Water Treatment Plant.

A small number of customers have been reporting earthy and musty tastes and odours from their water supply. In response, Irish Water have carried out sampling and analysis of the water supplies in these areas and can confirm that the water continues to fully meet chemical and microbiological regulatory standards and is safe to drink.

Reservoir levels have stabilised and reached full capacity, with network flows and pressure returning to normal operating conditions. The taste and odour issues experienced by some customers is likely to have been caused by the emptying of some of the reservoirs and distribution supply pipes which could have disturbed internal deposits in concrete structures, pipes, and fittings. However, the water fully meets regulatory parameters under the drinking water regulations and is safe to drink.

Irish Water, in partnership with Dun Laoghaire-Rathdown and Wicklow County Councils, continues to monitor the situation as water flows are expected to return to normal over the coming days as water flows to full capacity through the network.

Kevin Love, Regional Asset Operations Lead at Irish Water said, “Investigations continue into the likely cause of the taste and odour issues and we are looking into possible changes in raw water characteristics caused by reduced lake level and seasonal changes as we move from Summer to Autumn.

Kevin added: “Customers may continue to experience some temporary discolouration of water and odour issues because of the works at Vartry Water Treatment Plant last week, which will continue to improve over the coming days. For advice on clearing discoloration and airlocks, visit www.water.ie/water-supply/supply-issues/following-an-outage.”  

The Irish Water customer care helpline is open 24/7 on 1800 278 278 and customers can also contact us on Twitter @IWCare with any queries. For updates, please visit the Water Supply Updates section of our website. 

Irish Water is responsible for the delivery of all public water and wastewater services in Ireland. We are committed to continuously upgrading and developing critical infrastructure to support the growth needed in housing and across our economy, while protecting the environment and safeguarding water supplies.