Understanding Schedule 3

Schedule 3 is the buzzword in the water and drainage industry but what will it do and how well do we understand it?

In simple terms, Schedule 3 will mandate the inclusion of Sustainable Drainage Systems, or SuDS as we know it, into all new developments as part of the planning process. When The Flood and Water Management Act 2010 was enacted, the Welsh Government implemented Schedule 3 along with an approval framework known as the SuDS Advisory Board (or SAB) but England did not include this, until now! DEFRA confirmed some months back that it will bring Schedule 3 into force in England, hopefully in 2024 which puts pressure on local councils to ensure they have the approval framework in place in time.

The first word of SuDS is ‘Sustainable’ so if Schedule 3 is to be properly integrated and work, we all need to understand what Good SuDS looks like, and how to design, approve and maintain them. So let’s go back to the 4 Pillars of SuDS as a key starting point -:

  1.  Water Quantity – commonly known as attenuation, we have been doing this for many years but still get flooding in some areas so can we reduce this further and factor in changing rainfall patterns. The main design concern is that we store clean water so maybe Water Quality should be No 1.
  2.  Water Quality – the lack of clean water is a bigger risk to human survival than climate change so we need to look after every drop and this is why it’s so important to have the highest possible standard of pollution capture.
  3. Amenity – integrating SuDS into other features that we use in our daily lives.
  4. Biodiversity – use nature-based SuDS, design infiltration, and plant-based treatment, BUT keep in mind how much Mother Nature can cope with, we are still learning how to do this Sustainably ….

The primary objective of Schedule 3 is to ensure the above is embedded into the drainage design of all new developments as well as a strategy for adopting and maintaining the system in perpetuity. It’s this management and maintenance that raises some big questions of who, how much, and how long, as no one wants high maintenance costs, let alone the huge costs of replacement/upgrades to assets in the years ahead.

The critical factor is that we chose and design SuDS with a clear understanding of the long-term effects of our short-term choice. Whether you are an engineer, developer, or local authorities, are you ready and informed to make the right ‘Sustainable’ choice today that will ensure we are delivering Great SuDS for many years to come?

Designing Good SuDS

The foundation of any good SuDS design is clean water, be it for reuse, infiltration, or piped to a suitable water body. If this is not done, the system will fail at some point incurring environmental damage, bad publicity and high remedial costs. So it becomes vital to know how the assets we include now will perform in the years ahead, not just that the Mitigation Index is met as a number. Ask, will a Swale (or similar natural device) deliver the right level of treatment for your site in 20, 30, 40 years time, if not then you must include a proprietary or manufactured system that will deliver the same performance for the rest of its life. This leads us on to maintenance….

Maintenance of SuDS

All SuDS features need to be serviced in some way or another at some point, we ignore this at our peril, it is vital that we understand and plan what the costs are and when it will be done. Below are some examples to help illustrate the issues that can creep up on us and give a nasty shock –

  1. Ponds are nice and less expensive to build but without pre-treatment, dredging costs can run into hundreds of thousands of pounds every 20 – 30 years, but install an upstream vortex separator (or similar proprietary device), the cost will be around £1500 per year to service (depending on size) which is a huge difference. Please also note the SuDS Manual C753 states that ponds must have primary pre-treatment.
  2. Have you ever seen permeable paving being cleaned and do you know what it costs? The manufacturers have a life span on these surfaces and the long-term cost is rarely factored in or allowed for. By contrast, good proprietary treatment devices deliver consistently high water quality for a much lower lifetime cost, in all but the lowest trafficked areas.
  3. There is a big push to understand microplastic and rubber particle pollution, and what happens when these elements impregnate the soil horizons of a swale or filter drain, as we all know they don’t just disappear. So make sure the treatment is up to the task over the life time of the site.

Understanding and planning the long-term cost and effectiveness of SuDS is the biggest challenge we have as no one wants the maintenance costs but bad designs now will cost us in both pound notes and environmentally in the years to come.

SPEL Products Can Help

SPEL has a leading range of SuDS-certified products designed and certified to meet most site applications and deliver exceptional water quality.

Each system ensures effective Mitigation of the 3 main pollutants (TSS, Metals & Oil) across the Pollution Hazard Index, this makes for simple specification and sizing of a treatment device that will deliver more than the required surface water quality standard as set out in the CIRIA SuDS Manual C753. By utilising our certified products, engineers, developers, and local authorities can confidently implement sustainable drainage systems that have undergone rigorous testing and assessment and will maintain the treatment levels for decades to come.

SuDS-certified products contribute to building climate-resilient communities that can manage stormwater sustainably. It has never been so important to alleviate flood risk and eliminate pollution from our stormwater, remember our rivers, streams lakes and ponds are the unfortunate conveyance of pollution to the seas and oceans! Well-designed SuDS will reduce peak flows and enhancing water quality, our SuDS systems must provide robust defence against extreme weather events and protect both the infrastructure and environment that we depend on.


So welcome Schedule 3, it represents a crucial step forward in improving not just water quality but our environment and the habitat that we share with it right across the globe. ‘Clean water is a right, not a privilege’ and we often don’t know it till we don’t have it so lets work together to provide for future generations. Sir David Attenborough said recently “Everywhere the availability of fresh water is becoming increasingly unpredictable and uncertain.”

Humanity can survive with higher temperatures but we cant survive without Clean Water so start to safeguard these very precious resources today.

Need more information about our SuDS systems?

Contact: sales@spelproducts.co.uk / (01743) 445 200