A complete, plain-English guide to how the Kingdom manages stormwater — why it matters in an arid climate, the difference between infiltration and attenuation, how soakaways are designed, the standards that govern them, and the systems NGS supplies.
Saudi Arabia's climate is arid, but its rainfall is not gentle — it tends to arrive as short, intense bursts. On hard urban surfaces and low-permeability ground, that water runs off quickly and can overwhelm conventional drainage, causing localised flooding. As the Kingdom builds out Vision 2030 cities and giga-projects, managing that runoff sustainably — slowing it, storing it, and where possible returning it to the ground — has become a core part of responsible infrastructure design rather than an afterthought.
These are the two core strategies, and the choice is driven by the ground:
The same high-void geocellular units serve both roles; what changes is whether the system is open to the ground (infiltration) or lined and throttled (attenuation).
A soakaway is an underground store that lets stormwater infiltrate into the ground. Modern soakaways replace the old gravel-filled pit with modular geocellular cells that hold far more water in the same volume — a void ratio above 95 percent — while carrying the loads above them, from landscaping to trafficked pavement. For the full detail on how these are specified and sized, see the Geocellular Soakaway Design Guide.
At a high level, the design follows four steps:
The NGS Design Studio runs this analysis automatically and produces a sized design with an engineering summary you can submit.
Stormwater design in the Kingdom sits within the Saudi Building Code and municipal approval framework (MOMAH and Balady), supported by recognised engineering references such as CIRIA C753, CIRIA C737 and BRE Digest 365. The full index — every code and authority, summarised with a link to its official source — is on the Saudi stormwater & soakaway standards page.
The codes and authorities that govern SuDS, soakaway and geocellular design — SBC, MOMAH, Balady, CIRIA, BRE.
Read →How geocellular soakaways work, when they suit a site, how they are sized, and the AquaCell specifications.
Read →Size your own soakaway to the recognised standards and download an engineering summary.
Open the tool →The AquaCell geocellular range and NGS's full stormwater capability across the Kingdom.
View division →What is sustainable urban drainage (SuDS)?
SuDS manage rainfall close to where it falls — using infiltration, storage and controlled release rather than piping it straight away. Components include soakaways, attenuation tanks and permeable surfaces, aimed at reducing flood risk and managing water quality.
What is a soakaway and how does it work?
An underground structure that stores stormwater and lets it infiltrate into the soil. Modern soakaways use modular geocellular cells (void ratio above 95 percent) instead of gravel, and work only where the ground can absorb water — confirmed by a percolation test.
Are soakaways suitable for Saudi Arabia's ground conditions?
It depends on the site. Soakaways suit ground with adequate infiltration and low groundwater. Where soils drain poorly, or with high groundwater or sabkha conditions, attenuation with controlled discharge is used instead. A percolation test and ground investigation decide.
What standards govern stormwater and soakaway design in Saudi Arabia?
SBC 701 for building drainage; MOMAH and Balady for municipal approvals; and CIRIA C753, CIRIA C737 and BRE Digest 365 as the common engineering references. See the standards page for each official source.