With Ofgem’s RIIO-3 Final Determinations now published, gas network operators have greater clarity on investment priorities, regulatory expectations and performance targets for the next five years. Covering the period from April 2026 to March 2031, RIIO-3 represents one of the largest network investment programmes in recent years and will play a significant role in shaping how the UK’s gas infrastructure is managed, maintained and modernised.
But what are the key points every gas professional should know?
Significant Investment Has Been Approved
Ofgem has approved £28.7 billion of upfront investment across Great Britain’s energy networks under RIIO-3. Of this, £14.8 billion has been allocated to Gas Distribution Networks (GDNs) and £3.2 billion to Gas Transmission, demonstrating the continued importance of maintaining a safe and resilient gas network as the UK progresses towards its long-term energy transition goals.
This investment provides network operators with the resources needed to maintain critical infrastructure, improve reliability and address emerging asset risks while continuing to deliver value for consumers.
The Iron Mains Replacement Programme Remains a Priority
One of the most significant areas of expenditure within RIIO-3 is the continued delivery of the Iron Mains Risk Reduction Programme (IMRRP). Ofgem has confirmed continued support for the replacement and decommissioning of Tier 1 iron mains, with all remaining Tier 1 mains, associated services and iron stubs required to be removed by the end of 2032.
As the programme enters its final stages, operators are likely to focus increasingly on identifying, prioritising and accessing the remaining sections of higher-risk infrastructure. Accurate asset information and efficient planning will become increasingly important as networks work towards meeting the deadline while controlling costs and minimising disruption.
Condition-Based Asset Management Is Becoming More Important
A recurring theme throughout the Final Determinations is the need for evidence-based investment decisions. Rather than adopting blanket replacement programmes, Ofgem expects network operators to demonstrate a clear understanding of asset condition and risk before committing expenditure.
This is particularly evident in areas such as Multiple Occupancy Buildings (MOBs), where condition assessments and targeted interventions are favoured over wholesale replacement. The emphasis on asset intelligence reflects a broader industry shift towards condition-based maintenance and risk-led decision making.
As a result, technologies that provide accurate information on pipe condition, joint integrity and network performance are likely to play an increasingly important role in helping operators justify investment and prioritise work programmes.
Operational Efficiency Remains Under the Spotlight
RIIO-3 continues Ofgem’s focus on productivity improvements across the energy sector. Network operators are expected to deliver more efficient outcomes through improved planning, better use of data and the adoption of innovative technologies.
For field operations, this creates a strong case for solutions that reduce unnecessary excavation, improve fault diagnosis and enable more targeted interventions. Technologies that allow assets to be inspected under live conditions, identify faults more accurately or support efficient repair activities can help reduce operational costs while improving network performance.
Customer Impact and Network Resilience Matter More Than Ever
While infrastructure investment remains a major focus, RIIO-3 places equal importance on customer outcomes. Reliability, resilience and service continuity remain central to the framework, particularly where large numbers of customers could be affected by asset failures or planned works.
This reinforces the value of proactive asset management strategies that identify issues before they become service-affecting events. Whether through network monitoring, leak detection, condition assessment or targeted repair programmes, the ability to intervene early can help operators reduce risk while maintaining high levels of customer service.
Looking Ahead
RIIO-3 is not simply a funding settlement; it is a framework designed to encourage smarter, more efficient management of the UK’s gas infrastructure. With £18 billion allocated across gas distribution and transmission networks, operators will be expected to balance safety, resilience, efficiency and customer outcomes while continuing to modernise their asset base.
The common thread running through the Final Determinations is clear: better information leads to better decisions. As networks work towards meeting RIIO-3 objectives, technologies that support inspection, monitoring, leak detection and targeted repair are likely to become increasingly valuable tools in delivering safer, more efficient and more resilient gas networks.
