01
About the Utility
Dŵr Cymru Welsh Water provides water and wastewater services across most of Wales and parts of the English border region. The operating company sits within Glas Cymru, a company limited by guarantee with no shareholders. Surpluses remain within the business or are returned to customers rather than distributed as dividends. Its service territory combines the main urban centres of south and north Wales with extensive rural and mountainous areas, creating materially different operating conditions across water-resource zones and catchments. The company is regulated economically by Ofwat, environmentally by Natural Resources Wales and for drinking-water quality by the Drinking Water Inspectorate. Its bilingual public-service obligations and not-for-profit structure are distinctive, while its operating pressures include ageing assets, environmental compliance, affordability and a step-change in investment delivery during the 2025–2030 regulatory period.
02
Water System
Welsh Water’s supply system is shaped by varied catchments: high-rainfall uplands and reservoirs in the west sit alongside drier eastern areas and growing climate variability. Water-resource planning therefore depends on catchment condition, treatment performance and the ability to manage supply across materially different zones. Drinking Water Inspectorate reporting records 236,830 regulatory tests for Dŵr Cymru in Wales during 2024, covering samples associated with 66 treatment works, 328 service reservoirs and 152 water-supply zones. Leakage remains a material performance issue. Ofwat reported total-company leakage of 261.6 million litres per day for 2023/24, an increase of 8.4 Ml/day on the prior year, while later reporting showed the three-year average still materially above its baseline commitment. Earlier leakage and consumption figures were subject to enforcement over misreporting, so they are not combined into a synthetic trend.
03
Wastewater System
A sufficiently clear current wastewater-treatment-volume figure is not available, so collection, discharge and capacity measures are not used as substitutes. Environmental performance remains a major pressure. Treatment works compliance was reported at 98.71% in 2024 against a 99.00% deadband. Natural Resources Wales recorded 2,064 listed storm overflows in 2024 and accepted a corrected company data submission after validation issues. The reported average was 48.9 spills for each overflow with spill data, a utility-specific measure that should not be read as treatment throughput or network capacity. Pollution and overflow reduction therefore sit alongside treatment upgrades, drainage planning and catchment measures as core priorities for the 2025–2030 investment period.
04
Performance
Reported against a 99.00% deadband.
An increase of 8.4 Ml/day from 2022/23, as reported by Ofwat.
Natural Resources Wales measure for Dŵr Cymru’s reported storm-overflow estate.
Category 1–3 sewerage pollution incidents
Natural Resources Wales annual assessment, 2020–2024
Annual Category 1–3 sewerage pollution incidents. Natural Resources Wales assesses the measure in relation to the sewer length for which the company is responsible; the chart shows incident counts, not a normalised rate.
Sources: Natural Resources Wales annual environmental performance reports for Dŵr Cymru Welsh Water, 2020–2024.05
Investment & Priorities
Dŵr Cymru Cyfyngedig reported £496 million of capital investment excluding infrastructure renewals expenditure in FY2025/26, down £12 million on the prior year. Separately, Ofwat’s PR24 final determination provides a £6.0 billion total expenditure allowance for 2025–2030 to deliver performance commitments and legal obligations. That regulatory allowance includes operating and capital requirements and is not presented as capital expenditure. Documented investment priorities include leakage control, supply-pipe and mains replacement, pressure management, wastewater compliance and the broader obligations of the 2025–2030 regulatory period. The company’s FY2025/26 total revenue was £1,169.8 million, influenced by a substantial increase in household bills reflecting AMP8 regulatory allowances.
06
Sustainability & Resilience
Welsh Water’s sustainability programme centres on operational decarbonisation and nature-based treatment. The company has a stated target of net-zero operational carbon by 2040, supported by renewable generation from wind, run-of-river hydro, solar photovoltaics and advanced anaerobic digestion. At New Inn in Torfaen, a £13 million constructed wetland is designed to treat storm-overflow discharge before it reaches the Afon Lwyd. The 1.8-hectare scheme provides a documented example of green infrastructure being used alongside conventional wastewater investment. Catchment restoration, including peatland, wetland and woodland measures, also links carbon management with source-water quality and climate resilience, although a single current consolidated measure for those activities is not available.
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Key Challenges
- Restoring confidence in leakage and consumption reporting after regulatory enforcement.
- Improving treatment compliance and reducing pollution and storm-overflow impacts.
- Renewing ageing networks across a large, predominantly rural service territory.
- Balancing a major regulatory expenditure programme with household affordability.
- Strengthening drought and supply resilience across materially different water-resource zones.