Mitigating Carbon Accounting Inconsistencies in the English and Welsh Water Sector.

The theme of interconnectivity emphasises the interdependent relationships between governance, industry, and environmental systems, core to industrial ecology. This study examines carbon accounting inconsistencies within the English and Welsh water sector, globally recognised for the first sector to commit to a sector-wide net-zero operational emissions target for 2030 (Water UK, 2020). Despite the adoption of the Carbon Accounting Workbook (CAW) since 2008 and standardised Annual Performance Reports (APRs), discrepancies persist in Scope 1, Scope 2, and Scope 3 emissions reporting. These variations hinder the sector’s ability to optimise resource allocation, align regulatory expectations, and support equitable decarbonisation pathways, potentially costing the customers to take on the NetZero burden.Longitudinal emissions data (2019 -2024) from APRs was collected from all 10 regulated water and wastewater companies through direct engagement with each organisation’s energy/carbon manager. The data were analysed using statistical methods to identify trends, variations, and sources of discrepancies. Initial findings reveal a significant percentile variation of over 25% in tCO₂e/Ml of water and wastewater treated, equivalent to ~26 tCO₂e/Ml treated. Additionally, Scope 1 water sectorprocess and fugitive emissions made up between 94% and 38% of total Scope 1 emissions - a range that deviates significantly from established literature (Liu et al., 2024). Despite operating under a unified reporting framework (CAW), this study reveals the various unstandardised methodologies companies used for calculating emissions, particularly for process emissions and chemical use