Bathing Water - Compliance & Assessment

Pre 2011: Prior to 2011 water quality was assessed on an annual basis against the legislated standards based on the percentage of samples complying with a range of microbiological and chemical parameters.

2011-2013: During the transitional period (2011 – 2013) just the two new microbiological parameters, Intestinal enterococci and Escherichia coli, were monitored and the results assessed for compliance with the water quality standards specified in the 1992 Quality of Bathing Waters Regulations (S.I. 155 of 1992) with Escherichia coli being considered to be equivalent to the previous parameter ‘Faecal coliforms’ and Intestinal enterococci being considered to be equivalent to the previous parameter ‘Faecal streptococci’. The sampling results were assessed for compliance with the guide and mandatory standards for the equivalent parameters specified in the 1992 Regulations.

A three tier water quality status system of ‘good’, ‘sufficient’ and ‘poor’ was used:

  • ‘good’ quality relates to compliance with both EU guide and mandatory values;
  • ‘sufficient’ relates to compliance with the mandatory values only and;
  • ‘poor’ classification reflects non-compliance with mandatory values.
Parameter Conversion for Assessment of Bathing Water Quality During the Transition Period (2011-2013) and Corresponding Limit Values and Assessment to be used   
Regulation (S.I. No. 79 of 2008) Regulation (S.I. No. 155 of 1992)   
Parameter Corresponding parameter Guide values Mandatory values

Intestinal enterococci

(cfu/100 ml)

Faecal streptococci/100 ml



(90% of samples)      


Escherichia coli

(cfu/100 ml)

Faecal coliforms/100 ml



(80% of samples)


(95% of samples)

* For the parameter Intestinal enterococci, all bathing waters get compliant with the mandatory value automatically as no corresponding faecal streptococci mandatory limit is specified in 1992 Regulations.   

From 2014: With effect from the 2014 bathing season, microbiological results for the latest and three previous bathing seasons will be used to classify bathing waters into four categories: ‘excellent’, ‘good’, ‘sufficient’ and ‘poor’ in accordance with the water quality standards specified in the 2008 Regulations with a classification of ‘sufficient’ to be achieved by 2015 for all bathing waters.

The criteria used in the new assessment take account of the spread of data and rather than just the percentage of samples complying with the standards set out in the legislation. It is based on the mathematical calculation of the 95th and 90th percentiles of log transformed data. The criteria used for inland waters differ from those used for coastal waters and this reflects the concerns that bacterial organisms tend to die off at a quicker rate in salt water than in fresh water. It is also a cautionary approach given that coastal waters could contain other faecal related bacteria and viruses. 


Water TypeParameterExcellentGoodSufficient
Coastal / Transitional Intestinal Enterococci 100 (*) 200 (*) 185 (**)
E. Coli 250 (*) 500 (*) 500 (**)
Inland Waters Intestinal Enterococci 200 (*) 400 (*) 330 (**)
E. Coli 500 (*) 1000 (*) 900 (**)

(*) based on a 95-percentile evaluation  (**) based on a 90-percentile evaluation

Other monitored waters where bathing occurs, but which are not formally identified as EU bathing waters, are not subject to the mandatory requirements of the Bathing Water Regulations 2008. Many are monitored at the minimum required frequency however the same water quality standards are used for assessment of their expected water quality.

Learn More

Download the latest Bathing Water Quality report, map and infographic

Check out the EPA bathing water quality information website,