Water Pollution

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When polluting matter enters a watercourse it results in water pollution. Please refer to the Water Pollution Act 1977, as amended for the definition of "polluting matter".  

There are potential sources of water pollution all around us, it is how these sources are managed that limits the risk. Pollution can reach water bodies through various pathways including rain water gullies, direct disposal or infiltration. Once pollution reaches a water body the biodiversity, ecological, physical and chemical quality of the water is at risk. This has knock-on effects for human health, amenity, recreation and tourism.

Section 3 of the Water Pollution Act 1977, as amended states 'A person shall not cause or permit any polluting matter to enter waters. Any person who contravenes such shall be guilty of an offence and shall be liable to a fine or/and imprisonment'.

Want to help reduce water pollution?

You can help prevent water pollution from your own home, see our list below!

  • Think before you flush - When certain items are flushed down the toilet, they can cause problems in our homes, wastewater treatment network and the environment. Items that should not be flushed down the toilet include cotton buds, baby wipes, medicines, nappies and sanitary items.
  • Think before you pour - Fats, Oils and Grease (FOGs) used in cooking can harden inside pipes when poured down the sink. This causes blockages in pipes and possibly the greater sewer network and may lead to water pollution. Instead of pouring FOGs down the drain, they should be left to harden and disposed of or recycled appropriately.
  • Minimise impervious areas - Impervious surfaces such as cobble lock driveways facilitate high flows of urban run-off direct to sewers. This contributes to flooding and overloading of the drainage network. This is of even greater concern where there is a combined sewer (one sewer receives both rainwater and foul waste) than where there is a separate network (one sewer for rainwater and one sewer for foul waste) as it results in more frequent spillages from combined sewer overflows.
  • Harvest rain water using a water butt and store it for later use i.e. gardening, car washing or toilet flushing. Water Butts are also effective in slowing down and reducing the flow of storm water to the sewer during heavy rainfall events.
  • Misconnection Inspection – See below for more information.


  • Many properties have two separate drains, a foul and a surface water drain. The foul drain takes the “dirty” wastewater from foul appliances such as toilets, sinks, showers, washing machines and dishwashers to the waste water treatment plant via the foul sewer. The surface water drain takes the “clean” storm water and conveys it to the nearest watercourse via the surface water sewer.
  • A misconnection is when your property/premises has foul “dirty” wastewater incorrectly plumbed to the “clean” surface water drain, which can lead to pollution of local rivers and streams.
  • Dublin City Council have dedicated misconnection crews who carry out daily misconnection inspections at domestic and commercial properties across the city. An inspection typically takes between 5-15 minutes and can be pre-arranged by appointment. Should a misconnection be found following an inspection, you will be informed on the day and DCC will send a follow up letter to your address requesting redirection of the misconnection within a specified time frame. DCC will revisit the property at the end of the allocated time frame to confirm the redirection. Failure to redirect a misconnection may result in legal proceedings.
  • It is the responsibility of the owner of the property to redirect a misconnection. It is an offence under Section 3 of the Local Government (Water Pollution) Act, 1977, as amended to cause or permit the discharge of polluting matter to waters. Furthermore, it is an offence under Section 16(7) of the Local Government (Water Pollution) Act, 1977, as amended to cause or permit the discharge of polluting matter, including sewage, to any drain or sewer provided solely for the reception or disposal of storm water. 
Dirty Dozen Campaign


Manage pollution at source What you can do to help!