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Upgrade of Warrenpoint Wastewater Treatment Works (WwTW)


Warrenpoint is a small town in County Down, situated on the northern shore of Carlingford Lough, approximately 7 miles south east of Newry. The shared water of Carlingford Lough marks the border between Northern Ireland and Ireland.

Due to its scenic beauty and coastal location Warrenpoint is popular with day trippers and the town can experience an influx of visitors during the summer months.

Existing wastewater treatment

Warrenpoint WwTW is located to the western edge of the town approximately 250m from the lough shoreline. Constructed in 1976, Warrenpoint WwTW serves Warrenpoint town and the neighbouring villages of Rostrevor and Burren.

The existing plant comprises an inlet works (6mm fine screening and grit removal), 4 activated sludge basins (treatment process using aeration) and 2 final settlement tanks. Storm water storage, sludge treatment and a sludge storage tank are also present to support the process. The existing works was designed for a population equivalent of 16,195, with treated effluent being discharged via a 300m long, 450mm diameter outfall pipe directly into Carlingford Lough.

Need for upgrade

Warrenpoint WwTW is now over 40 years old. Recent investigations show that the plant currently receives load from a population equivalent of 16,259, meaning that it is having to operate beyond its intended design capacity.

Current operational problems are due to excessive flows being pumped to the inlet works. This problem is exacerbated by network infiltration/ tidal ingress and inadequate flow balancing at the WwTW.

This results in un-attenuated flows, premature use of storm tanks in dry weather conditions and loss of untreated wastewater loading to Carlingford Lough. This factor is considered to be a significant potential source of wastewater pollution to Carlingford Lough, contributing towards the failure to meet ‘Good’ Water Framework Directive status.
Microbial reduction through tertiary treatment (a third level of treatment) and disinfection may be required to achieve the required water quality equivalent of Class B status with an aspiration to make progress towards Class A status.

The construction of a new treatment facility to cater for such an enhanced discharge consent would require significant capital investment beyond that available under the INTERREG VA programme. As such the SWELL project will concentrate efforts on alleviating immediate pollution problems but will take cognisance of the future treatment solution to make best use of the work and expenditure.

Warrenpoint Location


  • Improve inlet flow management and effective use of storm storage facilities during periods of heavy/prolonged rainfall.
  • Alleviate pollution resulting from unsatisfactory loss of biological loading to Carlingford Lough.
  • Improve water quality within Carlingford Lough through enhancement of the treated effluent quality.
  • Provide a solution that offers flexibility and reliability and be capable of serving the catchment needs over a 25-year project horizon.
  • Provide a works that complies with all relevant Water Industry specifications and NI Water asset design standards.
  • Provide additional treatment capacity thereby facilitating housing and trade growth within the area.

What the upgrade will involve

The Swell Project Waves


The upgrade at Warrenpoint WwTW will be carried out in two phases.
The first phase of work will be carried out under the SWELL project and the second phase will be done by NI Water as follows:


The first phase of improvements will address overloading and potential loss of wastewater loading to improve water quality within Carlingford Lough.


The second phase, which will follow on from the SWELL improvements, will ensure compliance with a more stringent discharge consent in accordance with NI Environment Agency requirements.

Progress Of Works

The Swell Project Waves
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