Water: Emissions
The hidden electricity bill behind every tap
What this tab covers The greenhouse-gas footprint of the commodity at a global level, split by lifecycle phase: extraction (or farming), refining and processing, movement, usage, and recycling or end of life. Intensities are per unit of product; the global total combines intensity with world output. Also covers other environmental impacts and the main levers to cut emissions. Emission intensity 0.27 kg CO2 per m³ range about 0 for untreated gravity supply to about 3.0 for seawater RO with pumped distribution on India's grid · 0.367 kWh/m³ (local conveyance 0.029 + treatment 0.198 + distribution 0.14) x 0.727 kg CO2/kWh (calculated); SWRO case 4.14 kWh/m³ (4.0 + 0.14) x 0.727 = about 3.0 kg (calculated)Per m³ of drinking water from a gravity-fed surface source with conventional treatment and pumped distribution, using India's grid emission factor (electricity only; wastewater excluded). Intensity: Derived from IFI TWG AHSA-004 (2020) default factors and CEA CO2 Baseline Database (FY2023-24 weighted average 0.727 t CO2/MWh). Global total: IEA World Energy Outlook 2016, Water-Energy Nexus; ADB COP28 session note (2023).
Share of footprint by lifecycle phase
Extraction 8% Refining / processing 54% Movement 38%Footprint by lifecycle phase
| Phase | Intensity | Share | Main sources of emissions | Notes | Source |
|---|---|---|---|---|---|
| Extraction | local pumped conveyance 0.029 kWh/m³; groundwater depends on lift (no default); long transfers 0.79 kWh/m³ | 8% | pumps lifting groundwater and moving raw water to the plant | For Indian farm tube wells this is the dominant energy use, and it rises as water tables fall | IFI TWG AHSA-004 (2020); share of 0.367 kWh/m³ (calculated) |
| Refining / processing | conventional treatment 0.198 kWh/m³; brackish RO 0.95-1.94; seawater RO 4.0 kWh/m³ (IEA range 2.5-6) | 54% | coagulation, filtration, disinfection; high-pressure pumps for desalination | Thermal desalination also needs about 250 MJ/m³ of heat (IEA) | IFI TWG AHSA-004 (2020); IEA 'Wired for water'; share of 0.367 kWh/m³ (calculated) |
| Movement | pumped distribution 0.14 kWh/m³ | 38% | pumping through city networks and to storage tanks; tanker trucks in water-short Indian cities (not quantified) | Leakage multiplies energy per m³ delivered | IFI TWG AHSA-004 (2020); share of 0.367 kWh/m³ (calculated) |
| Usage | not quantified in sources reviewed | – | heating water in homes and industry; irrigation pumping on farms | Outside the utility boundary; water heating can exceed supply energy | not in sources reviewed |
| Recycling / end of life | not quantified per m³ in sources reviewed; IFI TWG has deferred wastewater defaults | – | electricity for aeration and pumping; methane and nitrous oxide from sewage and sludge | Wastewater may account for up to 1.8% of global greenhouse gas emissions (ADB 2023) | ADB (2023); IFI TWG (2020) |
Other environmental impacts
Over-pumping lowers water tables, dries wells and springs and can cause land subsidence. Dams fragment rivers and displace people. Desalination returns concentrated brine, about 1.5 m³ per m³ of fresh water across all plants (calculated from Jones et al. 2019: 142 million m³/day of brine against 95 million m³/day of product). Untreated sewage and farm run-off pollute rivers and aquifers with nitrate and pathogens.
Levers to cut emissions
- Cut leakage and non-revenue water, which saves treatment and pumping energy per m³ delivered
- Shift desalination from thermal plants (about 250 MJ/m³ heat) to reverse osmosis and power it with renewables; IEA sees desalination's electrification rate rising from 28% today to 50% by 2035
- Use high-efficiency pumps and solar pumps for irrigation in India
- Capture biogas from sewage sludge and control methane at treatment plants
- Reuse treated wastewater locally instead of long-distance transfers (0.79 kWh/m³ for 200 km or more)
India
India's grid emits about 0.727 kg CO2 per kWh (CEA, FY2023-24), so every kWh used to lift or treat a cubic metre adds about 0.73 kg CO2. Groundwater pumping for irrigation, 215 bcm a year (CGWB 2025), is the largest water-energy use, and falling water tables raise it.
Emission figures are indicative global averages from the life-cycle studies named; actual footprints vary widely by site, energy mix and method.