Sewage: why we desperately need a solution
In the news this week, there has been much media coverage on the issue of sewage pollution in our seas. Drone footage of drainage water contaminated with sewage being discharged into Langstone Harbour has been shared widely by various media outlets and this has generated both shock and outrage in the local area. Unfortunately, this is not an unusual sight around the Solent and anyone can find the history of all discharges from our sewage system on Southern Water’s own Beachbuoy site: https://www.southernwater.co.uk/water-for-life/our-bathing-waters/beachbuoy
These discharges are a direct result of the way our sewage system, much of which dates back to Victorian times, is designed and operated. Our sewers combine “black water” from our toilets, “grey water” from our sinks, washing machines and dishwashers, drainage rainwater from our roofs, and surface runoff from roads, urban areas and agricultural land. All of this contaminated water mixes together in our sewers and, normally, is then piped to sewage treatment plants for treatment.
The problem is that things are not always normal, in fact, they are not normal quite a lot of the time. Climate change is bringing heavier rainfall events, and this combined with continued development pressure, means that our Victorian-designed sewage system often struggles to do its job. Although there are storage tanks to provide a buffer during periods of higher flow, during more extreme rainfall events, or as the result of blockages or other system failures, the system can be overwhelmed. At that point, the only thing that stops contaminated wastewater from backing up into our homes and onto our streets is to allow it to be discharged into our rivers and seas.
If you stand beside one of these Combined Sewage Outfall (CSO) pipes when it is discharging or see the aftermath of such a discharge on our beaches, often characterised by the presence of disposed sanitary products, used condoms and wet wipes, it is easy to be repelled.
Sewage - even diluted sewage - is nasty stuff. It presents a health risk for the many people who use the Solent for bathing, water sports, boating and work. The same Escherichia coli (E. coli) bacteria that makes swimming dangerous can be filtered out and concentrated by filter feeding marine animals, like marine bivalve molluscs, which form part of the food chain for many species, including us. E.coli contamination is one of the key monitoring measures which determine the safety, not just of our bathing waters, but of our shellfish production areas. If there is too much E. coli in the water, fisheries are closed, we lose a source of local sustainable seafood, and fishermen’s livelihoods are put at risk.
The Solent is already under tremendous pressure from poor water quality: overfertilized with excess nutrients, like nitrates from agricultural runoff, and many other sources. These nutrients cause microscopic plants in the marine plankton and the green seaweed we often see blanketing and choking our harbours to grow unchecked, smothering mudflats and overwhelming other species and habitats. For example, Natural England have identified nitrates and nutrient overload as the single most important pressure preventing our internationally important seagrass meadows - and the Marine Protected Areas they characterise - from reaching good environmental status.
Sewage from CSOs may not be the most important source of nutrients in the Solent, but neither is it insignificant, and as it peaks during extreme conditions, it can put marine species and habitats under particular stress. It is also responsible for human health risks specifically linked to sewage, rather than to other nutrient sources.
Discharges from CSOs also contain all the other contaminants which wash off our land and streets when heavy rainfall events overwhelm the sewage system. Oil and tyre dust from our cars – significant sources of oil and plastic pollution - as well as chemicals and all kinds of litter.
There must be a better way. We know so much more about our marine environment now than we did forty or fifty years ago. Our understanding of the importance of natural capital, ecosystem services and climate change resilience provided by a heathy marine environment has led us to a point where it has become clear that to accept the practices of the past is no longer a defendable option. There must be massive investment in this side of the water management cycle: better treatment, better and bigger stormwater storage and separation of blackwater and grey water systems.
It will be costly, both for the water companies and for all of us as water users, but this is something we simply have to do because, at the moment, we are dodging our responsibility and asking the marine environment to foot the bill. Combined with all the other pressures it faces, including the overarching impact of climate change, the marine environment is telling us that our time is up, and that we have to clean up our act or face a future without the support it provides.
Over the last few weeks the Environment Bill has been ping-ponged between MPs and Lords who have been debating key amendments, including to place a legal duty on water companies to take all reasonable steps to ensure untreated sewage is not discharged from storm overflows - finally forcing water companies to tackle their sewage pollution record.
Earlier this week, the Government told MPs to reject the sewage overflow amendment. But now, thanks to tireless campaigning, the government has announced a partial U-turn and water companies will be required by law to show a reduction in sewage overspills over the next five years.
We are yet to see the detail of the government's amendment, and we may need to continue campaigning on this issue, but we hope that they will grasp the opportunity to create healthy, safe and Wilder waterways for both wildlife and people to enjoy for generations to come.