Private wells play a crucial role across rural Ireland in supplying domestic drinking water to about 800,000 people – about half our rural population.
Three-quarters do not report having a water treatment system, meaning their drinking water is mostly unmonitored and untreated, potentially exposing them to significant health risks.
While risk of well contamination can vary based on local geology and land uses, Ireland’s alarming rate of waterborne illness rates indicate an urgent need for nationwide action to address this growing problem.
An expanding body of scientific research links private well use to outbreaks of waterborne illnesses, with Ireland regularly reporting the highest rates of Shiga-toxin producing Escherichia coli (STEC) in Europe; up to 10 times the EU average notification rate in recent years. Indeed, Ireland has ranked worst in the EU for 10 out of the past 12 years.
STEC (which is also referred to as VTEC) is a potent and infectious strain of E.coli that cause severe illness. Up to 10 per cent of cases can result in haemolytic uraemic syndrome (HUS), a life-threatening condition that can lead to kidney failure and may be fatal.
Vulnerable groups such as young children and the elderly are especially at risk of severe illness and hospitalisation. Worryingly, Ireland consistently reports the highest rate of STEC among children aged up to four and the second highest rate for those aged 65 and over in the EU.
Despite these significant public health concerns, there is no regulation of water quality from private wells. Irish academics, including Paul Hynds of TU Dublin and Jean O’Dwyer of UCC who surveyed thousands of well owners and tested their water, have provided a compelling body of evidence showing that government action is required.
The research tells us that rural settlement patterns, private well density, septic tank density – there are 500,000 such systems – and proximity to herd density (6.5 million cattle) all play a role increasing the likelihood of STEC infection.
While dairy farm wells are subject to water testing for Bord Bia audits, rural household wells do not have to be monitored.
Although domestic wastewater treatment – or septic tank – systems may be inspected, this occurs at a rate of less than 0.25 per cent annually. Of septic tank systems inspected, approximately half fail each year. Of those that fail, around half of those are identified as a risk to human health and the environment.
Extreme weather events have been shown to lead to significant spikes in waterborne diseases
Such contamination risks and consequent groundwater vulnerabilities may be further amplified by Ireland’s changing climate.
Warmer temperatures, wetter winters, and more frequent extreme weather events create ideal conditions for groundwater contamination. Heavy rainfall, for instance, can lead to overland flows of pollutants, while flooding increases the risk of microbial pathogens infiltrating groundwater sources.
Extreme events have been shown to lead to significant spikes in waterborne diseases. Even during droughts the persistence of microbial contamination in private wells remains a public health concern. With a growing rural population adding 5,500+ septic tank systems annually, the public health risks are only becoming more urgent.
In spite of the body of evidence now available, many rural residents report excess confidence in their own well water quality and there is limited public awareness or government action to address the issue comprehensively.
A national programme of free well-water testing in Ireland would cost just over €5m annually
The Canadian province of Ontario offers a valuable example of how proactive policies can improve private well safety. Ontario provides free well-water testing and has robust public awareness campaigns, resulting in nearly 40 per cent of well users testing their water annually – five times the rate in Ireland.
Additionally, half of Ontario’s well owners have installed water treatment systems, compared to just 24 per cent reporting treatment in Ireland. Notably, microbial contamination rates in Ontario are ten times lower than those reported in Ireland, according to research by a group of Irish and Canadian academics led by UCD’s Simon Mooney.
Adopting similar measures in Ireland could lead to significant improvements in well maintenance and public health outcomes. A national programme of free well-water testing in Ireland would cost just over €5m annually. Combined with awareness-raising initiatives, this would represent an important public health and climate measure for rural communities.
Well water contamination is acknowledged in the Government’s 2024 Climate Action Plan and a number of its sectoral adaptation plans, but the absence of action puts people at risk of ongoing outbreaks of waterborne diseases, placing an unnecessary burden on our healthcare system and endangering rural communities.
Prof Eoin O’Neill is director of UCD Earth Institute and professor in environmental policy at University College Dublin
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