Redbridge Council invests in Hydrorock technology to reduce flood risks and protect communities

Published: 13 October 2026

Redbridge Council is expanding its use of the innovative flood defence technology, Hydrorock, to reduce flood risks in the borough and help build more resilient communities.

The advanced underground system was installed in High Road, Seven Kings; Claybury Broadway, Clayhall; and Tomswood Hill, in Barkingside after all three sites were identified as potential flood risks due to previous episodes of flooding.

Recently completed, these three projects are part of the Council’s £11m, 10-year investment plan to strengthen flood defences, protect at-risk communities and build a more flood-resilient borough.

Hydrorock works like a giant underground sponge. Installed beneath the road, it quickly absorbs rainwater during heavy downpours, storing it temporarily before releasing it slowly into the sewer network. This prevents the sewer system from becoming overwhelmed from sudden surges of water from heavy rainfall - one of the main causes of road flooding.

In addition to the underground flood defence works, sections of the road were also re-surfaced with permeable paving to further help absorb rainwater off the road and into the underground Hydrorock blocks. 

With flash floods and intense storms occurring more frequently because of climate change, the borough has ramped up investment in flood defence schemes to help protect local homes and businesses against flooding.

The  use of Hydrorock is part of a more extensive programme of flood alleviation works carried out this year by Redbridge Council’s Highways Team, among which was the installation of six new rain gardens in Clayhall, Woodford and Hainault:

•    Stonely Road, Clayhall
•    Harewood Drive, Clayhall
•    Knighton Drive, off Monkhams Lane, Woodford
•    Knighton Close, off Monkhams Lane, Woodford 
•    Forest Road, off Monkhams Lane, Woodford
•    Addison Road, Hainault

Featuring plants, shrubs, and other greenery, rain gardens are designed to mimick natural drainage processes to slow the flow of surface water entering sewers and drains. 

Cabinet Member for Environment and Neighbourhoods, Cllr Jo Blackman, said: “Hydrorock is just one of the ways we're helping protect homes, businesses and communities from flooding. As extreme weather becomes more common, we're investing in innovative and practical solutions that strengthen our flood defences, reduce local flood risk and help build a more resilient Redbridge for the future."

The flood risk reduction schemes installed this year can temporarily hold around 426,000 litres of storm water, which is then slowly released into the sewer system. 

That's the equivalent of around 2,400 household baths of water!

To date more than 2.2 million litres of rainwater can now be held at one time and slowly released into the sewer system in Redbridge through the combination of flood alleviation measures that have been installed across the borough so far.

Further flood risk reduction works have also been earmarked for action under Redbridge’s Flood Risk Management Strategy and Surface Water Management Plan.  

For more information on this, or to stay flood aware and find out what you can also do to help protect your home from flooding go to:  www.redbridge.gov.uk/crime-and-public-safety/crime-prevention-advice/flooding/