ACO Water Management says local authorities and developers should prioritise surface-level rainfall interception after flash flooding in Birmingham highlighted pressure on UK urban drainage systems.
ACO Water Management has urged local authorities and developers to tackle flash flooding at the surface, following heavy rainfall and flooding in Birmingham on 27 August.
The drainage solutions specialist said recent flooding has again highlighted the challenges urban drainage systems face as they respond to extreme weather events.
ACO is calling for greater use of sustainable drainage systems, including rain gardens, permeable surfaces and attenuation systems, to intercept and slow rainfall before it reaches sewers.
Flash flooding highlights urban drainage pressure
ACO said recent heatwaves have delivered long dry spells, baking the ground unusually hard.
When intense rain follows, water can run off rather than naturally soaking away. The company said this is especially problematic in urban areas such as Birmingham, where paving and hard surfaces have expanded through urban creep.
That can cause water to reach combined sewers within minutes, overwhelming them and pushing untreated flows into homes, roads and watercourses.
ITV News reported that Birmingham experienced significant flooding after storms, with Birmingham City Council advising people to avoid walking, cycling or driving through flood water. Read more from ITV News.
Surface water management prioritised over larger pipes
ACO said the instinct is often to increase pipe capacity, but argued that this can be expensive, disruptive and does not address water arriving at the network in the first place.
Instead, the company said local authorities and developers should use surface-level measures to store water and release it slowly.
These measures can include rain gardens, permeable surfaces, attenuation systems and retrofitted tree streets or car parks.
ACO said multiple small interventions across a catchment can collectively reduce flash flood risk.
The company’s sustainable drainage systems guidance describes SuDS as a way of managing the full surface water cycle, from where rain lands to where it re-enters the natural environment.
ACO calls for wider SuDS uptake
Sam Hawkins, Head of Specification & Design at ACO Water Management, said: “We keep trying to solve the urban flooding issue by upsizing pipes, but that is the most expensive and least effective solution. The real answer revolves around using a range of hard and soft sustainable drainage systems (SuDS), such as rain gardens and attenuation systems, to reduce the volume of water that makes it to the sewer system. The challenge here is that SuDS uptake remains inconsistent.”
Schedule 3 of the Flood and Water Management Act has not been enacted in England, meaning sustainable drainage remains a matter of policy rather than law.
ACO said adoption and interpretation therefore vary widely between local authorities and developers.
The UK Government’s national standards for sustainable drainage systems set expectations for managing surface water flood risk, water quality, amenity and biodiversity in developments.
Rain gardens can support flood and drought resilience
ACO said the same systems that help protect places during downpours can also recharge groundwater during drought.
Hawkins added: “Importantly, the same systems that protect us in a downpour also recharge groundwater during drought. As we swing harder between the two extremes, designing for both has become essential.”
The company said surface-first drainage design can help urban areas respond to both heavier rainfall and prolonged dry periods.
This approach is increasingly relevant as climate change contributes to more volatile weather patterns, including intense heat, drought, storms and flooding.
Urban flood resilience needs catchment-level action
The Birmingham flooding adds to wider concern over the ability of existing drainage networks to manage rainfall intensity in built-up areas.
ACO said local authorities and developers should consider surface water interception earlier in the design process, rather than treating drainage as a downstream pipe-capacity issue.
The company said combining small interventions across streets, car parks, gardens and developments can help reduce runoff before water reaches the sewer network.
For more coverage of flood resilience and surface water management, visit H2O Global News’ Flooding section.
Source: ACO Water Management
