Press release

Storm overflows monitoring hits 100% target

Every storm overflow across England’s water network is now monitored.

This was published under the 2022 to 2024 Sunak Conservative government

100% of storm overflows across the water network in England have now been fitted with Event Duration Monitors (EDMs), meeting the ambitious target set by the government to do so by the end of 2023.

Event Duration Monitors increase transparency by measuring how, when and for how long a storm overflow is in operation. This shows the public when discharges are happening, and helps the government and regulators to better hold water companies to account for illegal sewage spills and improve knowledge of overflow operation to identify where improvements can be made.

In 2010, just 7% of storm overflows had monitors fitted. Since then, the government has driven an increase in monitoring, with 100% oversight of overflows now achieved. This delivers on commitments in our Plan for Water which sets out our plans for more investment, stronger regulation and tougher enforcement in the water sector.

The installation of monitors rapidly accelerated under this government in 2013 when Lord Benyon instructed water companies to increase their storm overflow monitoring.

Storm overflows are an automatic safety valve that release excess pressure on the network from flooding and heavy rain – preventing sewage backing up into properties and stopping widespread mains pipe bursts across the country. They should, however, only be used under strict permit conditions. Increased monitoring will give government and regulators the information they need to take action when permits are breached.

Environment Secretary Steve Barclay said:

The completion of storm overflow monitoring is a major step forward in better protecting our precious waterways, as well as the communities and wildlife that rely on them.

The wealth of data collected from these monitors will ensure that we know the full extent to the problem – increasing transparency, revealing the worst-offending overflows, and enabling regulators to hold polluters to account.

This step is just one of many ambitious actions set out under our Plan for Water, which is delivering more investment, stronger regulation, and tougher enforcement across the water system.

Environment Agency Executive Director John Leyland said: 

After eight years of work, every storm overflow is now monitored, giving us much more information about where and when storm overflow discharges are happening. 

This increased transparency will allow the Environment Agency to better tackle illegal discharges from storm overflows. We are dedicated to investigating those that breach their strict permitting conditions.

We take our responsibility to protect the environment very seriously. We are also strengthening our regulation by expanding our specialised workforce, increasing compliance checks, and using new data and intelligence tools to inform our work.

Water UK Chief Executive David Henderson said:

With 100% of the near 15,000 storm overflows across England now monitored we have the best, most comprehensive and accessible monitoring system in the world. This data will be invaluable in ensuring investment is targeted at those sites which urgently need improvements.

Storm overflows are a design feature and act as a release valve after heavy storms. Water companies want them to operate as little as possible, which is why we are seeking regulatory approval to invest £11 billion over five years – three times the current rate – to increase the capacity of our sewers and prevent much more storm water entering the system in the first place.

As well as the expansion of EDMs, the Government has taken significant action throughout 2023 to boost water quality and resilience and hold polluters accountable for environmental damage.

As part of our Plan for Water, over £2.2 billion of new, accelerated investment is being directed into vital infrastructure to improve water quality and secure future supplies, with £1.7bn of this being used to tackle storm overflows to cut over 10,000 discharges.

This builds on stringent targets on water companies to reduce storm overflows, outlined in our Storm Overflow Discharge Reduction Plan – driving the largest infrastructure programme in water company history of £60 billion over 25 years. This will result in hundreds of thousands fewer sewage discharges every year by 2050. The Plan frontloads action in particularly important and sensitive areas including designated bathing waters, meaning the overflows causing the most harm will be addressed first to minimise impact.

Polluters now face unlimited financial penalties for breaching permits and polluting the environment thanks to changes to Variable Monetary Penalties (VMPs), which are civil sanctions issued by the Environment Agency. The move is designed to offer a more rapid form of punishment compared to criminal prosecution.

Furthermore, government has given Ofwat increased powers to ensure water company dividends are linked to environmental performance while the regulator has also tightened the rules on bonus payments.

Updates to this page

Published 30 December 2023