Beaches and Bathing Water Quality
Dublin City Council monitors bathing water quality at its two designated bathing waters namely Dollymount and Sandymount Strands. Monitoring is also carried out at non-designated bathing waters including Merrion Strand, Shelly Banks, Half Moon and North Bull Wall.
Bathing Water Quality
Dublin City Council is responsible for monitoring bathing water quality at its two designated bathing waters namely; Dollymount and Sandymount. Merrion Strand was declassified as a designated bathing water from the 1st June 2020.
The bathing season is from 1st June to September 15th each year, with pre-season sampling commencing in mid-May.
In addition, Dublin City Council also undertakes water quality monitoring at undesignated bathing areas, namely; Merrion Strand, Shelley Banks beach, the South Bull Wall at the Half Moon Swimming Club, as well as the North Bull Wall. At least twenty samples are taken from each location during the bathing season. Furthermore, Dublin City Council continue to monitor water quality throughout the year, outside of the bathing season on a fortnightly basis.
Assessment of water quality involves analysis of two types of bacteria (E coli and Intestinal Enterococci) which may be present in the water. These bacteria are indicators of water quality. The results are categorised in accordance with Bathing Water Regulations, 2008. Bathing water quality is classified as ‘excellent’, ‘good’, ‘sufficient’ or ‘poor’ and these classifications are based on the concentrations of the two bacteria species detected in samples of bathing water.
Temporary Bathing Prohibitions, Advisory and Prior Warning Notices
To protect bather health, it may be necessary to advise against or prohibit bathing at Dublin City Council’s bathing areas. Bathing water quality is particularly impacted by weather conditions, with factors such as rainfall amount and intensity, temperature, sunlight and tidal conditions being the main influences. Faecal matter from dogs and birds on a beach can significantly impact on water quality as can temporary overflows from urban drainage infrastructure.
Additionally, if Dublin City Council receives information which indicates a risk of deterioration in bathing water quality, a precautionary advisory or prohibition notice may be issued. Examples of such include a prediction of an extreme weather event or an exceedance/non-compliance from the Wastewater Treatment Works (i.e. effluent quality fails to meet the conditions of discharge as set out in the Wastewater Discharge Licence issued by the EPA for the Works).
The Environmental Protection Agency (EPA) and Health Service Executive (HSE) have established a protocol outlining various recommended actions to be taken by local authorities where, levels of bacteria in the bathing water exceed the satisfactory standard. In such circumstances, the local authority consults with the HSE in the first instance before proceeding with an agreed action. The public are informed of the short term pollution event through social media, web notifications and by erecting temporary signage at the locations affected. The website www.beaches.ie shares the latest information on national bathing water quality. Swim restrictions and annual water quality ratings can be found here. In addition, Dublin City Council operates a series of electronic signs on Dollymount and Sandymount Strands which notify the public when it is unsafe to swim. Once the event has passed and water quality returned to a satisfactory standard, the public are immediately informed.
Identified bathing waters are bathing waters (sea, river or lake surface waters) which Dublin City Council consider to be widely suitable by the public for bathing. Identified bathing waters are monitored, managed and assessed under the requirements of the 2008 Bathing Water Quality Regulations. Dublin City Council also monitor a number of other waters which are not formally identified. We refer to these as ‘other monitored waters’.
Each year Dublin City Council is required for the upcoming bathing season to identify bathing waters (sea, river or lake surface waters) within their area which they consider to be widely used by the public for bathing. At present, 18 local authorities have identified 148 bathing waters which is approximately 1 for every 40 km of coastline. Please find further information on public participation at the attached link.
Public participation is generally sought during the preceding bathing season. The EPA has produced guidance for the public on what information is required to nominate bathing areas and how this should be assessed, both of which are available to download from the Resources page of the EPA www.beaches.ie website. Please find further information on public participation at the attached link. If your particular beach is not identified by Dublin City Council this could be for various reasons such as low numbers of bathers, accessibility issues, poor water quality or limited amenities.
The bathing season in Ireland runs from 1st June to 15th September. All identified bathing waters are monitored, assessed and managed under the requirements of the 2008 Bathing Water Quality Regulations during this period. All bathing water monitoring results are available on the Dublin City Council website, posted in hardcopy at the beaches or on the EPA website Beaches.ie during the bathing season.
Bathing waters are sampled on a regular basis from the end of May to mid-September to assess the microbiological quality of the water and to minimise any public health risk. The minimum number of samples required to be taken during the bathing season is 4. Dublin City Council take many more samples than this with 20 samples taken across 6 bathing water locations. In recognition of year round swimming, Dublin City Council continues to monitor and publish results outside of the bathing season.
Samples are tested for two types of faecal bacteria, Escherichia coli (also known as E. coli) and Intestinal Enterococci. The Central Laboratory count the number of each these bacteria, which may indicate the presence of pollution, usually originating in sewage or animal waste. The results of the analysis are assessed against the standards defined in the 2008 Bathing Water Quality Regulations and on a four-year data set using a statistical approach.
All formally identified (designated) bathing waters are reported on Dublin City Councils bathing water website www.dublincity.ie/bathingwater or on the EPA website Beaches.ie. All bathing water monitoring results are available on the Dublin City Council website, posted in hardcopy at the beaches or on the EPA website Beaches.ie during the bathing season.
Samples are taken in the bathing waters where there is greatest risk of pollution or where there are the most bathers, usually where the lifeguards are stationed. Samples are taken in water about 1 metre deep (if safe to do so). The location of the sampling point is shown on the notice boards at bathing waters, in the bathing water profiles and on maps in Beaches.ie.
All natural waters contain bacteria, usually as a result of contact with the soil. Most of these bacteria are quite harmless however some types of bacteria which can be found in faeces, both animal and human, can cause illness. The two organisms, Escherichia coli (known as E. coli) and Intestinal Enterococci, occur in very large numbers in the gut of warm-blooded animal and human faeces.
E. coli and Intestinal Enterococci are analysed in assessing bathing waters compliance and are used as ‘indicator’ organisms where their presence in large numbers in bathing waters is a warning of a possible health risk from other harmful bacteria and viruses which might be present. E. coli provide a good indicator of pollution in fresh waters while in seawater Intestinal Enterococci are a better indicator of pollution as they survive for longer periods. E. coli and Intestinal Enterococci can survive for several days up to several weeks in waters.
E.coli results are available the following day (21-24h) following receipt of the sample. The exception to this would be where a sample is taken but held over night before being analysed e.g. a Sunday or weekend sample. The Intestinal Enterococci result is then issued the following day (48h +) once the various confirmation tests have been completed. Occasionally the Enterococci test can take a little longer depending on the bacteria and this can delay the issuing of the result although this occurs quite rarely. Both result are required for compliance with the 2008 Regulations and HSE Guidelines.
The Council endeavours to report results of analysis within the 48hour window post sampling. We broadly support the use of complimentary rapid tests/analysis for the determination of public health risk and to support routine monitoring. DCC is also working in partnership with 3rd Level institutions as well as Industry specialists to evaluate the suitability of complimentary methodologies for testing bathing waters. It is important to note that alternative approaches to sampling and testing of bathing waters needs to be considered with reference to the standard methodologies in order to demonstrate equivalence
Faecal contamination makes water unsafe for recreational activities such as swimming. There are five major sources of pollution responsible for the faecal bacteria in our bathing waters. These sources increase when it rains, washing more pollution into rivers, lakes and seas and in times of very heavy rain can overwhelm sewage systems. The impacts of these events are generally very short-lived lasting 1-2 days.
- Pollution from waste water treatment plants & sewage systems – bacteria from sewage can enter our waters as a result of system failures or storm overflows or directly from sewage works.
- Water draining from urban areas - water draining from urban areas via street drains and culverts following heavy rain can contain pollution including animal and bird faeces from roads and other paved surfaces.
- Domestic sewage – misconnected drains and poorly located and maintained septic tanks can pollute surface and ground water systems.
- Animals and birds on or near beaches - dog, bird, and other animal faeces can affect bathing water as they often contain high levels of bacteria (much higher than treated human waste).
The two organisms, E. coli and Intestinal Enterococci, tested for in assessing bathing waters compliance are used as ‘indicator’ organisms where their presence in large numbers in bathing waters is a warning of a possible health risk from other harmful bacteria and viruses which might be present.
Bathing water samples are currently assessed against the standards defined in the 2008 Bathing Water Quality Regulations. All bathing water monitoring results are available on the Dublin City Council website, posted in hardcopy at the beaches or on the EPA website Beaches.ie during the bathing season.
The likely water quality status of each individual sample is assessed as either 'Excellent', 'Good', 'Sufficient' or 'Poor'. In the case of 'Excellent' water quality the risk of contracting gastro-intestinal illness is predicted to be ca. 3%, in Good waters ca. 5%, in Sufficient waters 8-9% and in Poor waters ca. >10%.