Soakaway Crate Sizing Calculator

Estimate required storage volume and crate count for a soakaway at 95% void ratio. Indicative only — confirm with a percolation test (BRE Digest 365) and structural design.

Impermeable area drained (m²) roof / driveway / yard the water runs off

Design rainfall depth (mm) UK typical 1-in-100yr event ~ 40–60 mm; use your local figure

Storage safety allowance climate-change / factor of safety uplift

Crate module volume (m³) Storm Manage HD module 1000×500×500 = 0.25 m³

Required storage

4.1 m³

StormCell HD crates17

Approx. excavation footprint4.4 m³

Get an engineer-reviewed sizing & FOB quote

Method: storage = area × rainfall/1000 × safety factor. Crate count = storage ÷ (module × 0.95 void). A soil infiltration (half-drain) check and load-class/cover-depth design are required before ordering.