April 2026 saw rainfall levels 23% below average in the UK, raising drought concerns for the coming summer months. Longer-term forecasts indicate that Summer 2027 could be the hottest on record, driven by a super El Niño weather pattern. These changes increase pressure on drainage systems to manage less water at times and more at others.
Four principles to manage water sustainably
ACO Technologies recommends a clear methodology to adapt drainage design to future climate pressures:
- Collect: Systems should be designed to handle extreme rainfall events, such as a 1-in-100-year storm, with added capacity for the predicted impacts of climate change.
- Clean: Before water continues downstream, the system must remove pollutants like metals and hydrocarbons. Tools like the Simple Index Approach from the Ciria SuDS manual assist engineers in achieving this.
- Hold: On-site attenuation slows water release, reducing flood risk. Nature-based solutions such as swales and ponds, combined with engineered attenuation where necessary, ensure consistent performance while supporting biodiversity and amenity.
- Reuse: Blue-green roofs combine engineered and natural solutions to capture rainwater. This water supports green infrastructure, lowers urban temperature, enhances biodiversity, and mimics natural water cycles.
Balancing scarce and abundant water
The challenge is twofold: conserving water during dry periods while managing more frequent and intense rainfall. This balance requires designs that store and reuse water efficiently, and prevent pollution and flooding.
Site application across UK roads
These principles affect projects on motorways, A-roads, and local authority schemes. For example, surface water drainage on the M25 slip roads can be designed to cope with extreme downpours and capture runoff for reuse in roadside landscaping. Biodiversity benefits from swales installed within central reservations and verges.
Mindset shift for long-term water security
Terry Wilkinson, Specialist Design & Application Engineer at ACO, said: “Extreme weather is becoming more common at both ends of the spectrum. Without large-scale intervention, water stress and scarcity will lead to what we call water bankruptcy. By prioritising collecting, cleaning, holding and reusing water in every project, we can protect this vital resource and support the environment.”
ACO advises contractors and engineers to plan drainage schemes that address both drought and flood risks under UK-specific regulations like NRSWA and the Traffic Management Act.
More on ACO’s environmental initiatives is available at ACO.co.uk
