The UK aims to capture and store 20–30 Mt \(\hbox {CO}_{2}\hbox {e}\) annually and produce 10 GW of low-carbon hydrogen by 2030. This study evaluates the potential water resource impacts of these decarbonisation efforts across five UK water company regions: Anglian Water, Northumbrian Water, Severn Trent Water, United Utilities, and Yorkshire Water. Projected \(\hbox {CO}_{2}\) capture and hydrogen production rates are obtained from publicly available project databases and converted into associated water withdrawal rates using specific water intensity factors (SWIF) for \(\hbox {CO}_{2}\) capture, blue hydrogen production and green hydrogen production. These SWIFs are derived through a combination of literature review and Integrated Environmental Control Model (IECM) simulations. Parameter uncertainty and project start-time uncertainty are incorporated using Monte Carlo simulation. Water withdrawals are spatially allocated to water company regions and compared with existing regional water availability forecasts derived from UK Water Resources Management Plans (WRMP24). Results indicate that additional water demand due to decarbonisation in the UK could reach 860 ± 150 ML/day by 2050, driven equally by \(\hbox {CO}_{2}\) capture, blue hydrogen production, and green hydrogen production. Regional impacts vary, with significant deficits projected for Anglian Water and United Utilities by 2030 and for Yorkshire Water by 2040, while other regions are expected to maintain surplus capacity. Recommendations include adopting technologies with lower SWIF values, enhancing collaboration between decarbonisation project managers and water companies, establishing regional desalination hubs, redistributing water resources, and implementing adaptive water management strategies to ensure sustainable resource use.
