Why Are Stormwater Overflows a Problem?

In the UK, sewerage systems were historically built to handle both rainwater and wastewater in the same pipelines. However, this type of design is vulnerable during periods of heavy rainfall, when the excess precipitation can cause the sewage to flood the surrounding area or even back up into people’s homes and businesses. As such, stormwater overflows solve this issue by discharging diluted effluent into rivers and oceans.

Because of the problems associated with it, this type of sewerage system has not been installed in Britain for over 50 years. However, the legacy of the design remains today, with more than 15,000 stormwater overflows in operation throughout England alone. Thanks to external pressures such as climate change, population growth and urban creep – alongside an increasingly morally bankrupt wastewater management industry – stormwater overflows are now becoming a serious issue.

A perfect storm

At their inception, stormwater overflows were meant to serve as an emergency stopgap measure to be deployed only infrequently. However, the population of Britain has swelled rapidly in the last century, meaning that the wastewater infrastructure in the country is no longer fit to deal with the increased demand. Add to this the fact that urbanisation has reduced the number of green areas capable of absorbing moisture and drains are increasingly becoming overwhelmed.

Meanwhile, the problem is exacerbated even further by the knock-on effects of climate change. Extreme weather events have increased in intensity and frequency in recent years, with bouts of prolonged heat and drought followed by violent storms and torrential flooding. This has meant that stormwater overflow discharge incidents have become dangerously commonplace.

Industry transgressions

To make matters even worse, those responsible for managing Britain’s water and wastewater systems appear to be asleep at the wheel – or even worse, actively avoiding their environmental responsibilities. A crucial component of wastewater management is monitoring, but since 2010, companies have been allowed to self-report any contamination incidents for which they are responsible.

However, there are suggestions that certain organisations are neglecting to do so or else discharging sewage illegally into rivers and seas in order to avoid penalisation. In 2020, the Environment Agency published a report that showed that raw sewage had been discharged from stormwater overflows into UK waterways for more than 3.1 million hours on over 400,000 occasions. That’s hardly the emergency measure that was intended at the inception of stormwater overflows.

What can be done?

First and foremost, better regulation of the industry is imperative if such rampant pollution is to be brought to heel. Integrating the latest technology (including both hardware and software) to make water data management smarter is a strong step forward, but equally regulatory bodies must make it impossible for continue transgressing. That means handing out fines that will actually hurt their business models, as has already happened on occasion.

A longer term solution to the issue would be to overhaul Britain’s sewerage system by doing away with stormwater overflows altogether. However, this will take a monumental effort and significant investment, as well as many years to enact. More immediately achievable green solutions include combating urban creep and preventing run-off through wetlands, swales, green roofs and porous surfacing. A combination of these ideas is likely to be necessary to turn the tide of stormwater pollution in the near future.