Thames Water's power costs were £223.1 million in FY 2025/26, against £219.7 million a year earlier. The company says hedging kept the rise to about 2%, at a time when chemical and energy prices ran above the levels assumed in its regulatory settlement.
A wind contract to 2030
In December 2025 Thames Water signed a five-year power purchase agreement with RWE. The Camster onshore wind farm in Caithness, rated at 50 MW, will supply 132 GWh a year until 2030, about 14% of the 931 GWh of grid electricity Thames Water bought in FY 2025/26. All purchased electricity is from renewable sources, so market-based Scope 2 emissions were zero.
Less power from its own sites
Self-generated renewable electricity covered 20.2% of electricity use in FY 2025/26, down from 23.8% in FY 2021/22, as on-site generation fell from 297.1 GWh to 253.3 GWh. Combined heat and power outages in FY 2025/26 raised grid imports and pushed more fossil fuel into boilers. Power income from selling self-generated electricity was £17.8 million.
Carbon without a budget
Ofwat awarded Thames Water no allowance for net zero schemes in the 2025–2030 period. The company missed its new operational emissions commitments in the first year, incurring £4.07 million of penalties, and its net zero goals remain under review.
Where Thames Water's best energy opportunities lie, how sludge consolidation and solar procurement could change its generation share, and what the creditor funding position means for energy investment are set out in the full report. The full report, Water-Energy Nexus: Thames Water, is available for USD 499 at https://ourfuturewaterintelligence.com/reports/water-energy-nexus-thames-water. For a free overview, read the Thames Water Utility Snapshot at https://ourfuturewaterintelligence.com/utilities/thames-water.