NI Water has updated Belfast City Council representatives on the current state of wastewater infrastructure in the city, highlighting the impact of long-term underinvestment on the ability to build new homes and jobs as well as contributing to a growing problem in Belfast Lough.

At a recent presentation to Councillors, NI Water set out how reductions in allocated capital funding during the current six‑year Price Control period (PC21), including for 2025/26, have significantly affected investment in the Belfast area.

Dr Stephen Blockwell, Head of Investment Management at NI Water, told Councillors that focus is now firmly on the next Price Control period (PC28), which will set investment levels from 2028 onwards.

Dr Blockwell said:

“As determined by the Utility Regulator, a fully funded NI Water is essential to provide the critical infrastructure needed to underpin Northern Ireland and Belfast City Council’s ambitions for housing, economic growth and environmental protection. Without urgent and sustained investment in the wastewater system, the city faces ongoing pollution risks, and constraints on development.”

Capacity constraints and environmental pressures

NI Water outlined the scale of the challenge across Belfast’s wastewater network. Of the 192 storm overflows in the city, 156 are currently classed as unsatisfactory, contributing to pollution risk and limiting the ability to accommodate new connections. Capacity constraints mean that many proposed homes in Belfast cannot currently proceed without significant capital upgrades.

The presentation also highlighted environmental pressures in Inner Belfast Lough, where nutrient pollution is contributing to algal blooms with socio-economic impacts. Verified modelling shows that wastewater discharges are a significant source of bacteria and nitrogen entering the Lough and, unlike Lough Neagh, the discharges are the primary cause of pollution which can only be resolved by major infrastructure upgrades.

Investment focussed on asset maintenance rather than upgrades

NI Water says that despite these constraints, it continues to progress investment where funding is available, although this is focussed on asset maintenance rather than upgrades. In Belfast, this includes projects such as the £8.2 million and £8.7 million base maintenance investments at Belfast Wastewater Treatment Works. In addition, there is a £6.7 million stormwater storage investment at Glenmachan Upper Falls Wastewater Treatment Works.

The projects form part of around 30 schemes currently underway in the city, with a total value of approximately £91 million.

However, NI Water explained that major elements of the flagship Living With Water Programme for Belfast (LWWP), a £1.9 billion long-term plan to address flooding, wastewater capacity and environmental performance, have been significantly impacted by funding reductions during PC21. As a result, most of the planned upgrades have been paused.

Stable, multi-year funding settlement is needed

Looking ahead, NI Water estimates that around £7 billion of investment is required across Northern Ireland to address wastewater capacity, environmental compliance and resilience. The organisation stressed that while short-term or in-year funding allocations can unlock limited development in specific locations, they cannot replace the need for a stable, multi-year funding settlement.

Dr Blockwell added:

“Short-term injections of funding can help in the immediate term, but they do not provide a sustainable solution for critical infrastructure. Long-term, fully funded investment through future Price Control periods is essential if Belfast and Northern Ireland are to meet housing demand, protect the environment and support economic development.”