Unfortunately, the UK has now suffered a major flooding incident every year since 2007, affecting 100,000 properties in the process[i]. To this end, contractors and developers, particularly on residential projects, are increasingly required to formulate flood defence provisions, such as Sustainable Drainage Systems (SuDS) within their development plans. In this feature, Tim Sandberg, Category Manager – Soil & Underground at Marley Plumbing & Drainage, explains what this means for the merchant sector and how merchants can use SuDS to create an exciting, new revenue stream within their businesses.

Whilst wet weather is nothing new for us Brits, climate change is making extreme storms and flooding far more commonplace across the country. In a major 2014 report, the UN Intergovernmental Panel on Climate Change warned that the UK was “very likely” to see more heavy rainfall events by 2100[ii]. And in fact, this February ranked as the UK’s wettest on record, in a series dating back to 1862[iii]. This is worrisome, particularly as one in 10 new homes in England have been built on land at the highest risk of flooding[iv]. In response, authorities at both a national and local level have sought to enact change, passing a number of bills designed to emphasise the importance of effective flood defence protocols.

Most notably, in 2010, the government passed the Flood and Water Management Act[v]. For the first time, developers were legally required to submit plans for the sustainable drainage of surface water on construction projects considered a flood risk. Additionally, the legislation removed the automatic right to connect to public sewers, giving local authorities more power to approve new drainage systems, such as SuDS, and their connection to public sewers. However, in recent times, there seems to be some drive to expand the scope of this act and to accelerate the uptake of SuDS across the UK. In fact, in Wales, all new developments over 100m2 have been required to include SuDS since 2019[vi]. Similarly, the revised National Planning Policy Framework states that all major developments should now incorporate SuDS unless it would be inappropriate to do so[vii].

Given this momentum towards further SuDS adoption, contractors and developers have been working hard to familiarise themselves with the concept and its associated solutions. As such, for merchants, there’s now a strong financial incentive to follow suit and to become more accustomed in discussing and recommending SuDS. Particularly as the market is relatively new, moving forward, merchants willing to develop knowledge in this area could easily position themselves as experts in the field. In turn, this endeavour will not only help to generate more revenue through increased product sales but could also enable merchants to deliver real value to those buying from them, helping to elevate levels of customer satisfaction.

A great introduction to the solutions available can be gleamed from Marley's Flowloc system. The SuDS solution was recently relaunched in response to the aforementioned rising demand amongst contractors, developers and housebuilders. The innovative system, which comprises a Vortex flow control unit with a pre-fitted inlet filter, works in conjunction with a stormwater attenuation tank to control and manage the rate at which stored water is released into natural water courses or underground sewer systems during a storm event. Thanks to the proven vortex principle, which reduces the effect of a differential head of water, the solution can accommodate flow rates ranging from 2.5 l/s to 18 l/s. As such, with the solution, development teams can enact tailored control over their water discharge rates, ensuring they meet the levels stipulated in the approved planning application, or by the local water authority.

What’s more, the Flowloc system has been developed in a way that suits pre-existing construction practices, which makes it an easier sell for merchants. For one, the solution has been designed as a pre-packaged ‘drop-in’ solution, providing the polyethylene chamber, riser kit, flow control unit, inlet filter and overflow pipe all as one. Therefore, when compared to alternative concrete solutions, Flowloc provides a far more cost-effective, lightweight and efficient means of installation.

Maintenance concerns are also minimised, with the system manufactured with a withdrawal handle attached to the flow control unit and a chain to the inlet filter, meaning that all maintenance can be undertaken from surface level. More importantly still, merchants recommending the solution can be secure in the knowledge that any Flowloc specification will be supported by Marley Plumbing & Drainage’s dedicated technical support team. The company’s industry-leading technical professionals will ensure that any design or installation queries are dealt with swiftly.



[i] Agyepong-Parsons, J. (2020). ‘Devastating number of homes’ damaged by floods since 2007. [online] Available at: [Accessed 21 Aug. 2020].

[ii] Carbon Brief. (2014). How much flooding is in the UK’s future? A look at the IPCC report | Carbon Brief. [online] Available at:

[iii] Met Office. (2020). Record breaking rainfall. [online] Available at:‌

[iv] The Guardian (2020). One in 10 new homes in England built on land with high flood risk. Josh Halliday. [online] 19 Feb. Available at:

[v] HM Government. (2010). Flood and Water Management Act 2010. [online] Available at:

[vi] Sustainable drainage systems (SuDS) on Welsh new developments are now mandatory. [online] Available at:[Accessed 21 Aug. 2020].

[vii] Policy Connect (2018). Government Sustainable Drainage (SuDS) Review published (finally!) | Westminster Sustainable Business Forum. [online] Available at: [Accessed 21 Aug. 2020].