Water supply emission factor by year
| Year | Scope 3 (kg CO2e per cubic metre) | Change |
|---|---|---|
| 2026 | 0.19130 | 0.0% |
| 2025 | 0.19130 | +24.9% |
| 2024 | 0.15311 | -13.3% |
| 2023 | 0.17668 | +18.6% |
| 2022 | 0.14900 | 0.0% |
| 2021 | 0.14900 | -56.7% |
| 2020 | 0.34400 | 0.0% |
| 2019 | 0.34400 | – |
Total kg CO2e for the seven greenhouse gases, from the official DESNZ files for each year. 2026 factor ID: 17_404_4005_1_1. Where a factor jumps sharply between two years, it is usually because DESNZ changed its method or data source, not because the activity itself changed.
Worked example
Take an office using 1,000 cubic metres of water a year. 1,000 cubic metres × 0.19130 kg CO2e = 0.19 tonnes CO2e, reported as Scope 3, category 1 (purchased goods and services).
How to report it
Mains water is Scope 3 category 1, purchased goods and services, because it is treated and pumped by the water company. Wastewater treatment has its own factor and is reported as waste, category 5.
Where the data comes from
You'll usually find it in your water bills, in cubic metres. Keep the source documents: anyone checking your Carbon Reduction Plan or SECR report may ask how each figure was worked out.
Read more about how the factors change each year in our guide to the 2026 conversion factors, or see how we apply them in our methodology.
Related emission factors
- Wastewater treatment: 0.17088 kg CO2e per cubic metre
- Commercial waste to landfill: 520.58 kg CO2e per tonne
- UK grid electricity: 0.13096 kg CO2e per kWh
- All UK emission factors