Guest blog post by Professor Chad Staddon, Professor of Resource Economics and Policy
Sewage releases into rivers are a significant problem in Stroud District where I have lived for more than twenty years. They cause significant damage to the environment and pose a threat to public health. These releases occur mainly due to the fact that our sewage system combines surface water drainage and domestic sewage into a single underground network conveying all wastewaters to sewage treatment facilities and this system is increasingly frequently overwhelmed during periods of high rainfall. Over-development means that ever more housing is connected to an underground sewerage system of fixed capacity (unless major sewerage upgrades that typically take years are implemented). Climate change is increasing the frequency of high rainfall events and therefore of sewage releases.
According to data collated by The Rivers Trust, in 2022 there were over 300 raw sewage discharges reported by Severn Trent Water into watercourses within the Stroud District. Most sewage releases were caused by “insufficient hydraulic capacity”, meaning that the pipe network could not accommodate both domestic sewage and heavy rainfall. For example, a combined sewer overflow (CSO) in about 2 km from where I live spilled a mixture of rainwater and sewage into the River Cam on 47 separate occasions and for a total of 223 hours.
One of the primary concerns associated with sewage releases into rivers is the impact on public health. When untreated sewage enters rivers, it can contain harmful pathogens and bacteria, such as E.coli and salmonella. These micro-organisms can pose a significant risk to human health, causing a range of severe illnesses, including gastroenteritis, hepatitis A, and cholera. Sewage can also damage aquatic ecosystems, killing fish and other aquatic organisms, and lead to contamination of water sources that can affect drinking water quality.
Severn Trent, the water company responsible for sewage treatment in most of Stroud District, has acknowledged the challenges posed by sewage releases and in 2022-23 invested over £25 million in drainage system and the wastewater treatment plant improvements in Stroud. This investment is intended to improve the capacity of the existing sewage treatment infrastructure thereby reducing the frequency of sewage releases.
In addition to upgrading wastewater treatment infrastructure, there are other measures that could be implemented to reduce sewage discharges into rivers. District Councils, who have lead responsibilities for development permitting and control need to strengthen requirements around sustainable drainage. In fact, they already have the tools to do so, with a requirement that new developments apply the “drainage hierarchy”, prioritising on-site water management solutions before connecting to sewers or releasing to the natural environment. Solutions include the installation of green roofs and rain gardens in urban areas, and reinstating wetlands or ponds on larger development sites, all of which can help to reduce surface water runoff and therefore the volume of wastewater entering the sewer network. If we can reduce the amount of rainwater draining into the wastewater network then over-capacity situations will become less frequent.
The water sector regulator, Ofwat, also needs to do more to require water companies to invest more in the wastewater network. Through its role approving company business plans, including capital investment, Ofwat has a strong influence over how much water companies invest in the drainage and wastewater system. In fact Ofwat is partly to blame for the current high level of sewerage releases to the natural environment because it has not insisted on higher levels of water company investment, even when companies have proposed to do so. The water quality crisis is very much a regulatory crisis.
Public awareness campaigns can also help to raise awareness of the dangers associated with sewage releases into rivers and promote better environmental practices. These campaigns can encourage people to avoid flushing inappropriate items, such as baby wipes and cooking fat, down the toilet and to be more mindful of how we dispose of waste. Education programmes in schools could also help to promote better environmental practices and create a culture of sustainability among future generations. It is also great to see citizens’ groups getting involved in monitoring river and lake water quality.
Sewage releases into rivers are a significant problem where I live and up and down the country posing threats to both public health and the environment. To address this issue, stakeholders must work together to implement measures that reduce the frequency of these discharges and limit the environmental damage caused by them. By upgrading the sewage treatment infrastructure, encouraging responsible environmental practices, strengthening regulatory powers, and raising public awareness of the dangers associated with these releases we can protect the natural beauty of our waterways and create a healthier environment for all.
References:
1. The Rivers Trust (2023). Sewage in our Rivers, Available at: https://theriverstrust.org/sewage-map
2. Staddon, C. (2010) Managing Europe’s Water: 21st century challenges, Ashgate Press.
3. UK Parliament Environmental Audit Committee (2022) Water quality in rivers Fourth Report of Session 2021–22, https://publications.parliament.uk/pa/cm5802/cmselect/cmenvaud/74/report.html#