By Julie Waters
NORTHERN Ireland Water has no idea how much sewage is being discharged into local waterways, including the internationally renowned Strangford Lough.
The revelation comes just a week after it was revealed that tens of millions of litres of diluted sewage are being discharged into the Lough every year from a single Newtownards pumping station.
Now figures obtained from the Department for Infrastructure (DfI) show that fewer than four in 10 of Ards and North Down borough’s 231 wastewater storm overflows have been fitted with special monitors which record the level of sewage spills into local streams, rivers and sea.
The monitoring shortfall means there is no comprehensive record of how frequently many of these overflows operate, and, crucially, no way of establishing the volume of wastewater discharged.
The issue has raised fresh environmental concerns over the impact of sewage pollution on Strangford Lough and the borough’s wider network of rivers, coastal waters and other sensitive habitats.
Event Duration Monitors (EDMs) record when an overflow begins and ends and how long it lasts, but they do not measure the amount of wastewater released. Computer simulations estimate the volume of sewage discharged.
Killyleagh man James Kilpatrick, a strong critic of Northern Ireland Water and its failure to tackle sewage overflows, said the figures demonstrate a serious monitoring gap.
Of the 231 overflows across Ards and North Down, just 94 had EDMs installed in 2025, recording 2,159 spills.
With increasing concerns over heavier rainfall and the capacity of ageing wastewater infrastructure, campaigners are now calling for both comprehensive monitoring and major investment to tackle the problem at source.
As more EDMs have been installed over the past three years, an increasing number of spills have been detected. In 2023 just 29 had been installed, detecting 667 spills and the following year a total of 56 EDMs were fitted, registering 973 spills.
These spills take place when storm overflows, that are meant to act like pressure relief valves across the sewerage network, release excess wastewater into designated watercourses during heavy rain to protect homes and businesses from flooding.
Each of the borough’s 231 storm overflows is assessed by the Northern Ireland Environment Agency on a number of criteria including if the wastewater that is being spilled exceeds normal levels of concentration of foul water.
Other criteria for more sensitive water courses, such as bathing and shellfish waters, assess whether the storm overflow is exceeding a set number of spills deemed acceptable each year.
The limit is three spills in the bathing season for bathing waters or 10 spills per annum for shellfish waters.
Storm overflows that fail to meet the standard are designated as ‘unsatisfactory’; figures show that a total of 119 of storm overflows across Ards and North Down have been classified as ‘unsatisfactory’. A further 44 are ‘satisfactory’, 62 are ‘to be determined’ and six are ‘not modelled’.
Killyleagh man James Kilpatrick, a strong critic of Northern Ireland Water, said the figures demonstrate a serious monitoring gap. “EDMs are important because they give us an actual record of when an overflow operates, how frequently it happens and how long it lasts. They do not, however, measure the volume discharged,” he said.
“At the unmonitored sites, we don’t even have that basic real- world record, leaving us without a reliable picture of how frequently they operate and ultimately how much diluted sewage is entering our waterways.”
The local angler said with extreme rainfall events becoming an increasing concern, more information is needed ‘about what is actually happening on the ground’.
“We cannot properly manage what we cannot properly measure,” he said.
Mr Kilpatrick stressed that the best long-term solution was infrastructure investment. “Monitoring alone isn’t the solution. The only long-term solution is investment in the infrastructure itself. DfI needs to make wastewater infrastructure a genuine capital investment priority.”
He said: “Strangford Lough and the wider province cannot continue relying on
an ageing sewerage system that is struggling to cope with modern demands and increasingly extreme weather.
“The continued impact of these unquantified discharges on marine species, sensitive coastal environments, and human health urgently needs to be challenged.”
Mr Kilpatrick said: “The answer is to upgrade the system so that it is fit for the 21st century — reducing the need for storm overflows in the first place, protecting our rivers and marine environment, and giving communities the wastewater infrastructure they deserve. EDM monitoring can help show us the scale of the problem. Investment in the infrastructure is what ultimately fixes it.”
