As a civil engineer, I now describe myself as a ‘climate change engineer’, and in the battle against climate change, I’m losing.

I’ve been proud to do this job for our capital city for 31 years and have seen many changes in that time, but nothing as profound and frightening as the manmade changes to our climate.

Now for some good news.

On January 7th 2019, Wales became a global leader in an arm of sustainability, but I bet you didn’t know that.

Yet on that date, Wales was the first - and still the only - nation on the planet to have statutory legislation for sustainable drainage (SuDS).

The National Wales:

The National Wales:

Before and after photographs showing Bargoed Street in Grangetown, Cardiff, after Greener Grangetown's SuDS retrofit project, the UK's most award winning example of its type. Source: ARUP

It all stemmed from severe floods 15 years ago and a Westminster report called the Pitt Review. It made a series of recommendations, which included making sustainable drainage a legal requirement in certain circumstances.

The housing lobby in Westminster blocked this element of the recommendations, but it fell under a devolved area of competence. The Welsh Government chose to consult on it and after a few changes, enacted for Wales ‘Schedule 3 of the Flood and Water Management Act 2010’.

Here, any development where over 100sq m of run-off from rainfall materially changes due to the development, you need an SAB approval to build.

An SAB is a SuDS Approval Body which approves or rejects an application based on six statutory standards, including flood risk, water quality, biodiversity, amenity and long-term maintenance/ownership.

It’s fair to say that this legislation has caused a few challenges for councils, developers, designers, architects and anyone involved in development. The powers of an SAB are the same as in planning but independent of them.

Each of Wales’ 22 councils have an SAB role, but it’s also reasonable to accept that we are not wholly consistent in our interpretation. Yet, could it not be argued that the 22 planning bodies within those councils also have varying approaches?

The good news is that devolution has given Wales the opportunity to be a genuine global leader in this area of engineering and development, and at a time when there has never been more interest in all things drainage.

From my experience in the industry, doing the right thing will not be the norm unless legislation insists upon it. In Wales we can insist on the best solutions and if designed well, these are the best solutions for everyone.


The Welsh Government has worked hard to make the legislation work and, behind the scenes, is looking to have more consistency and support for SABS. From the coal face, we feel enormous responsibility to make the laws work, as the industry desperately wants us to succeed.

So what does the legislation mean? Well, the trick is to treat surface water management like a service that is provided to a new housing estate for example. We can all think of electricity, gas, telecoms and drinking water as services, but why not surface water too?

It’s actually the very hardest to design for as it relies on gravity, it falls when it wants and also in very unpredictable ways. In spite of that, I’m sure you can imagine which service is always designed last instead and first. 

However, that is where Welsh SuDS laws come in. They effectively force you to design for rain at the start instead of the end of a project layout. The end result is a cheaper solution, a better place to live and work, and simply a better design.

Is it really that simple? Well, yes it is. These unique Welsh laws mimic natural drainage in an urban environment, so why try and improve on nature?

SuDS also deliver multi-benefits; this is a buzz-phrase that, when translated, means you get more for your money - a lot more.

It’s all about making new developments cleaner and greener. And as we come to the end of a mammoth COP26 in Scotland, let’s remember that in one area of climate change, devolution has enabled Wales to be a true global leader.

Ian Titherington graduated with a Civil Engineering degree from the Polytechnic of Wales in 1990, and has since worked in various engineering roles within Cardiff Council, predominately specialising in drainage. He devised the brief for Greener Grangetown more than ten years ago, after working on a series of outfall intercepting pumping stations around Cardiff Bay, prior to its impoundment with the construction of Cardiff Bay barrage.

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