8 June 2026
Our Flood Team are in Housebuilder magazine, this time leading the discussion on sustainable drainage systems (SuDS) and Drainage Strategies.
Tom provided expert comments on how SuDS and Drainage Systems are impacted by the recent change in policies...
Which major housebuilders does MEC advise on SuDS and drainage systems?
Our typical clients for SuDS and drainage strategies includes housebuilders such as Barratt, Bellway, Bloor, David Wilson, Persimmon, Redrow, Taylor Wimpey and Vistry Group, but we also work with smaller, bespoke developers too, meaning our work can vary from single storey extensions to large, sustainable urban extensions.
What are the main issues facing housebuilders when dealing with surface water and pollution, and in balancing this with supporting biodiversity?
The most common pitfall is not incorporating drainage early enough in a development’s design, meaning it has to be retrofitted later. Doing this on new developments should be a last resort because it diminishes the wider benefits a drainage system offers. Instead, if drainage is considered at feasibility stage, infrastructure and landscaping can be planned and integrated into open greenspace, providing amenity and biodiversity benefits, which are two of the 4 pillars of good SuDS design.
Another challenge is that each local authority has its own requirements for drainage and SuDS, so there is no ‘one size fits all’ approach. Every site must be considered on its own merits, constraints, and potential. We’ve seen instances where a housebuilder has two sites down the road from each other, but in different authority catchments so are held to different standards. The best form of mitigation for this is to plan ahead. Being aware of any constraints will help limit the knock-on effects down the line.
How has the new NPPF changed how housebuilders approach drainage?
Both the published NPPF and draft consultation NPPF, which we anticipate being published towards the end of this year, place greater emphasis on ensuring that drainage is dealt with early, efficiently, and in line with the National Standards for SuDS. Together they provide the basis, or the bare minimum, of what developers should be striving to achieve and should be viewed as an opportunity rather than a target.
The latest updates also provide clarity on the application of sequential and exception tests, which in some cases is working in favour of housebuilders by allowing the consideration of mitigation as part of surface water flood risk analysis.
What are the key features of the new National SuDS Standards for England for housebuilders and how can they deal with these?
The key change for housebuilders to be aware of is the revision and re-prioritisation of the Drainage Hierarchy. This places stronger emphasis on ensuring all methods of discharge are explored, and discounted, before moving on to the next. Greater information is also provided on water re-use within sites, including the implementation of water butts and rainwater harvesting (even for communal uses) as well as the capture, storage, and discharge of the first 5mm of rainfall, usually the most heavily polluted runoff, within the site boundary. Permeable, above ground SuDS features are the best way to provide this.
We are also seeing more weight being placed on infiltration-based features, with several councils now requiring the feasibility of this method to be completed at outline stage through soil infiltration rate testing. This is especially prevalent where site conditions may be favourable to allow infiltration.
My advice for housebuilders to ensure compliance with the new standards remains to engage drainage engineers as early as possible. SuDS and drainage systems are more than pipes and ponds; they can be a tool to unlock a site’s full potential. When SuDS and drainage are allowed to follow the 4 pillars (Quantity, Quality, Amenity & Biodiversity) beyond the bare minimum, they have been proven to provide environmental, social and wellbeing benefits, creating developments that thrive and where people want to live, which in turn supports stronger demand and improved sales rates for developers.
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