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Saturday 4 February 2023 Dublin: 10°C
Sam Boal
Opinion Our water quality tests in Ireland are not good enough - the real picture is a lot worse
Professor Dearbháile Morris and Dr Liam Burke of NUI Galway say the EU-backed water pollution tests being used here do not give an accurate reading.

LAST UPDATE | Jun 11th 2021, 8:23 AM

THERE HAS BEEN an explosion of sea swimming in Ireland in recent times, and with that comes a demand for the best, up-to-date and detailed information about water quality.

Some 73% of the 148 beaches and lakes which are formally designated as swimming spots are deemed to be of an excellent standard under EU testing rules. Overall, 96% meet the minimum standards.

But there is a deeper and more detailed way to analyse the level of pollution, which is not only more revealing but also more concerning. We, a group of researchers at NUI Galway Antimicrobial Resistance and Microbial Ecology (ARME) group have done just that.

For several years, our team has been taking 30 litre samples from swimming spots and beaches around Galway, Cork and north Dublin. Our fieldwork and lab analysis found organisms of public health concern in bathing waters – some of which are designated as of excellent quality.

As well as that, in three pieces of research since 2017 we have reported the detection of antibiotic-resistant bacteria in swimming spots that are designated as of good or excellent quality.

Flawed testing

This raises the question as to whether the EU sanctioned testing regime is good enough. The sampling and analysis for the Environmental Protection Agency’s Bathing Water Quality Report are based on the EU Water Framework Directive. Those regulations require local authorities to carry out sampling and testing at least once a month between 1 June and 15 September.

The teams gather samples of water, approximately one litre, from the beaches and swimming spots and they analyse 100 millilitres of the water for bacteria that is found in faeces.

They get two outputs – the most probable number of E. coli present and the most probable number of Intestinal Enterococci present. Based on the number of these in the sample, the waters are designated excellent, good, sufficient or poor.

We do not believe those quality standards are high enough. And here’s why. One part of the research carried out by ARME involved 30 litre samples being taken from 50 locations around Galway, Cork and Fingal, Dublin over several years.

We ran the same tests as the local authority, with the same sample volume. But, we also ran the rest of our 30-litre samples through a special filter to catch any bacteria present. We then carried out molecular tests on extracted DNA in the search for a pathogenic form of E. coli called Shiga-toxigenic E.coli (STEC).

We detected this virulent bacteria in 57% of 84 seawater samples we analysed, some of which were from waters deemed to be excellent quality under the EU standards. The bacteria was also found in 78% of 27 lake and river samples we collected since 2016.

The discovery is not a one-off, nor is it isolated. Shiga-toxigenic E.coli (STEC) is carried naturally by cattle and sheep but it is a risk to humans and a very small quantity has the potential to do us serious harm. If one of us was to ingest as few as 10 cells it could cause serious illness including bloody diarrhoea.

Around 30% of STEC cases require hospitalisation and about 10% develop haemolytic uremic syndrome, a potentially fatal complication that causes renal failure. Unfortunately, Ireland consistently reports a much higher incidence of human infection with STEC than the rest of Europe – typically 10 times higher than other EU member states.

The research can be read in full on our website and people can also share what they feel are the barriers they see to using our seas, rivers and lakes and the reasons why they use these Blue Spaces.

Freshwater issues

Findings from other research are to be published in next month’s Environment International. It reveals an analysis of 39 water samples collected between November 2018 and July 2019 – 23 from the sea; five from rivers; four from estuaries; and three from lakes.

All of the freshwater samples, and 83% of seawater samples, met the excellent classification standard for the number of E. coli when we tested them according to the bathing water monitoring criteria.

Again though, more detailed analysis revealed something else. Antibiotic-resistant bacteria were detected in every water sample. And just over half of the bacteria that we isolated from the water were multi-drug resistant, known as ESBLs.

These superbugs are resistant to multiple second-line antibiotics, normally used to treat infections when the first line antibiotics fail. In five water samples, we even found CPE – the most worrying type of superbugs. These are resistant to even the last-resort antibiotics, the carbapenems.

Although ingestion of these superbugs may not make people sick, they can become established in the person’s gut, which we call colonisation. Some bacteria and superbugs can exist in our guts and do no harm. However, the risk increases, particularly for people who are vulnerable or immune-compromised.

Superbugs can get from a colonised person’s gut into other parts of the body such as the blood or urinary tract and cause infection. They can also potentially transfer from someone who is colonised to their close contacts, and this is a worry if they are vulnerable.

Effects on humans

The PIER project is looking into whether swimmers and surfers are more likely to be colonised with these superbugs than those who do not get into the water much. In order to build a picture of this issue, we need the public, particularly those who do not swim regularly, to support the research at

Ireland’s water quality has been improving in recent years. It is thanks to the EPA that we know that there are still 35 towns and villages where sewage is being discharged into rivers, estuaries or the sea without treatment.

It is the equivalent of 78,000 people flushing their toilets straight into natural waterways. In 2019, Ireland ranked 22nd out of 30 European countries for the quality of our bathing waters.

It is also thanks to the EPA that a closer eye is being cast over the E.coli or Enterococci that exists in our waters and the characteristics of those organisms.

Our research group has revealed important detail about the quality of our seas, rivers and lakes, but it has also raised important issues over the EU standards we are asked to apply.

The Covid-19 pandemic and the restrictions imposed on society are undoubtedly part of the reason why there has been such interest and upsurge in outdoor swimming – both for the physical and mental health benefits. An EPA sponsored survey suggested that 65% of respondents believed that their “Blue Spaces” were of a high enough quality to spend time in.

We rightly herald and celebrate our beaches, oceans, sea, rivers and lakes as some of the most scenic in the world and what we are doing in Ireland is correct – entirely correct under the EU regulations. But our team’s research into water quality is not about trying to put people off from visiting and using our “Blue Spaces”, it’s about realising that the inspection criteria needs to be changed.

We need to look for the characteristics of E. coli and not just the total amount of E. coli. We need to test our waters throughout the year and not just from June to September.

Our research findings and the EPA’s current call for research proposals on the understanding of STEC in our waters are vital to informing policy at a national and European level.

Professor Dearbháile Morris is Personal Professor of Antimicrobial Resistance and One Health, and Head of the Discipline of Bacteriology in the College of Medicine, Nursing and Health Sciences NUI Galway. She is Director of the Ryan Institute Centre for One Health at NUI Galway and established the Antimicrobial Resistance and Microbial Ecology Group in 2010. Dr Liam Burke is a lecturer and a member Antimicrobial Resistance and Microbial Ecology group and the Centre for One Health at NUI Galway.

RED FLAG: Our colleagues at Noteworthy want to find out to what extent swimming off Ireland’s coast is under threat from pollution. Support this project here.


Professor Dearbháile Morris & Dr Liam Burke
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