Assessment of the pollution incident performance of water and sewerage companies in England

Comparison of water and sewerage company pollution performance in relation to severity, frequency and self-reporting of pollution incidents is made difficult by differences in environmental and operational conditions. In England, the deterioration in pollution incident performance across the water industry, makes it important to investigate common trends that could be addressed at national and regional levels. Yet, to date there has been no external peer-reviewed analysis of national pollution incident data in England. This project aimed to analyse available pollution incident data to assess and compare the performance of water and sewerage companies in England. Results indicated that there was significant variation in pollution incident numbers and the severity of the impact on the water environment for different asset types (operational property of the water and sewerage company such as a sewage treatment works). Increasing numbers of pollution incidents from pumping stations and sewage treatment works, were largely responsible for overall increases in pollution incidents. The highest increase in pollution incidents in 2019, was observed from pumping stations. Variation was evident in company self-reporting percentages across asset types. There were significant positive relationships between the self-reporting percentages of pollution incidents and total numbers of reported pollution incidents per 10,000 km sewer length for pumping stations and sewage treatment works. These results indicate that in at least these asset types, an estimated 5% of pollution incidents could go unreported, if not self-reported by the company. Pollution events not reported quickly by companies, can lead to more severe impacts to the water environment so rapid and consistent reporting of incidents is crucial for limiting damage. The results have significance for the water industry internationally, because the issues presented here are not restricted to England. Whilst this research highlighted a number of key areas for more detailed analysis, in the short-term, research should focus on investigating best practice for reporting pollution incidents. It is important to get an accurate baseline of the number of pollution incidents and whether a proportion are currently going unreported. This research should seek to aid the standardisation of reporting practice across the water industry.