While the necessity of Schedule 3 of the Flood and Water Management Act (2010) has been widely debated, at the time of writing, it’s expected to come into force imminently.

This will make Sustainable Drainage Systems (SuDS) mandatory for most new developments.

With the Met Office stating that extreme weather is Britain’s new normal, Michael McIvor-New, permeable paving specialist at Tobermore, asks whether this delayed legislation goes far enough.

Surface water flooding threatens more people and properties than any other form of flooding in the UK.

SuDS, particularly permeable paving, are one of the most effective tools in our armoury.

Despite this, plans to ratify Schedule 3 into law in England in 2024 were delayed. As it stands, developments of ten dwellings or more (or the non-residential equivalent) must include a SuDS scheme unless deemed inappropriate. This means England relies on planning conditions and section 106/104 routes rather than mandatory pre-construction approval.

In contrast, Wales adopted Schedule 3 in 2019, making the implementation of SuDS schemes a legal requirement for all new developments, backed by 22 SuDS Approval Bodies (SAB), which ensure projects meet national standards. This gives the law teeth and signals the importance of SuDS in flood defence. However, when adopting Schedule 3, England must learn from Wales’s experience.

Consistency of design and delivery

SuDS consist of a variety of devices, each of which manages water volume and quality. SuDS schemes are most effective when incorporated early in the design with devices chosen based on the landscape and environment.

However, there have been cases where SuDS design has not been approached thoroughly, or where schemes have not been maintained correctly (which I’ll expand on shortly). When designed and installed correctly, permeable paving is one of the most effective and cost-efficient SuDS devices available.

To address this, Wales has recently established the SAB Society with the sole purpose of achieving more consistency through Welsh SABs.

Do we need a golden thread for SuDS?

The golden thread of information ensures a digital copy of safety information relating to the construction of high-risk buildings is retained. This ensures changes during construction or maintenance don’t undermine the safety strategy.

Like fire, flooding puts lives, homes and businesses at risk. This means the design, operation and maintenance of SuDS are critical safety information. How this information is transferred through the specification chain to the end user is inconsistent.

Landscape architects are often frustrated when well-designed SuDS schemes are scaled back during construction to save money. SuDS aren’t cosmetic, they’re essential flood risk mitigation. Better collaboration is needed, so specifiers and contractors understand the value and true costs of SuDS.

When approached as a system, for example, permeable paving typically costs less than asphalt solutions when factoring in wider site constraints for water storage. This will ensure what’s designed is delivered.

The need to educate homeowners about SuDS

After purchase, owners can take unilateral decisions about their property’s upkeep. In Cardiff, homeowners replaced permeable paving and swale planting with concrete. Without SuDS drainage, the estate floods.

This shows we must educate homeowners about SuDS. Just as you wouldn’t block a drain, each SuDS device contributes to the whole drainage system. Any alterations can impact performance.

But we can’t rely on education alone. Legislation must mandate property owners and councils to maintain SuDS devices to ensure climate resilience. This isn’t unprecedented. Property deeds contain clauses restricting boundary fences and walls, and the storage of caravans.

Backing the builders, not the blockers

The final part of the jigsaw is the water companies. Some actively support SuDS implementation but others won’t connect permeable paving to combined foul sewers. It’s bizarre because, unlike gullies, SuDS act as a speed hump for water flowrate. This alleviates pressure on water systems by allowing surface water to permeate through at a controlled rate.

In many cases, these projects are delayed until the local or unitary authority steps in and forces adoption. Legislation would overcome this.

Ultimately, the introduction of Schedule 3 is a long-overdue step forward. Making SuDS mandatory for all new developments signals recognition that flood mitigation cannot be left to chance.

But if we’re serious about climate resilience, the legislation must go further. A golden thread of SuDS information must be introduced to safeguard schemes from cost-cutting and mismanagement. There must also be clearer duties around long-term maintenance and we must help educate homeowners about how SuDS work.

Given that surface water flooding already impacts millions of properties, the question is not whether mandatory SuDS are the right move but whether legislators are bold enough to match the scale of response to the scale of the risk.