Why is my water discoloured and what’s the advice?

Public health remains our top priority, and the treatment process used by Uisce Éireann at the Lee Road Water Treatment Plant is fully in line with water treatment standards used nationally and globally. Uisce Éireann reiterates its public health advice that water is safe to drink when it is running clear. Water can be discoloured due to sediment from old cast iron pipes, works on the water network in your area or elevated levels of naturally occurring minerals such as manganese. More information can be found on manganese in the HSE’s Frequently Asked Questions on Manganese in Drinking Water.

We continue to advise customers experiencing discolouration, not to drink discoloured water and run the cold water tap in the kitchen for several minutes as this will usually restore water to a clear colour.  If the water doesn't clear after 20 minutes, please contact our dedicated line on 1800 278 278 or report via our online form below and our team will follow up. These reports are essential to help us to assist impacted customers and manage a real time response. This helps to specifically direct our short, medium and long-term remedial works.

There is approximately 600km of watermains in Cork City, of which 360km is made from cast iron and up to 100 years old, dating back to the 1920s. These pipes pre-date the foundation of the state.

The instances of discolouration occur mainly when treated water interacts with the aging cast iron pipe network or when upgrade or maintenance works dislodge sediment within the pipes.

Old cast iron mains in cork City typically have iron or manganese build up in the inside of the pipes and can suffer from sediment becoming dislodged which can travel to customers’ taps causing the water to appear black, brown, orange or tinted yellow in colour.

Cork City Water Supply has experienced periods with elevated colour in the water supply from August 2022, throughout 2023 and into 2024

These four categories interact with each other during periods of elevated colour which lead to complications in analysis, reporting and resolution.

  1. Network Water Main Breakages

    Colour events due to localised breakages and major upgrade works. These breakages need to be managed and repaired to minimise colour events

     

  2. Water Main Distribution System & Treated Water Chemistry

    Issues commonplace due to the age and deteriorating condition of the pipes. Leaching has been observed relating to the chemistry of treated water.

     

  3. Manganese In Source Water

    Rising Manganese levels in raw water are being observed nationally including at WTP. Manganese reduction step at plant will address this. 

     

  4. DMA Configuration – Network Rationalisation 

    Localised difficulties, in mainly older network areas results in increased customer disruption.

     

The network is also susceptible to weather conditions. Long spells of dry weather, wet weather and sub-zero temperatures cause the ground to move, an external non controllable factor that causes breakages and leaks, resulting in increased instances of discolouration in the network.