Council Regulations for Soakwells and Stormwater Drainage

Western Australian law requires property owners to confine all stormwater runoff within their property boundaries. The Department of Water encourages infiltration of rainfall at or near source to maintain the site water balance close to its pre-development hydrology. Soakwells allow rainwater to return to the ground where it falls, maintaining the water table when most of a block is covered by impervious surfaces (roofs and paving).

The number depends on your catchment area (roof and paving area in m²) and your local council's formula. Generally, use the council formula to calculate required volume, then consider: 1) Access restrictions (less than 2m width requires polypropylene), 2) Available space considering minimum distances from footings and boundaries, and 3) Ideally group soakwells in as few locations as possible (typically front and/or rear of property).

If no specific council regulation is given, the standard "1 in 20" calculation can be used: roof area (m²) × 0.0125 = required volume (m³). For example, a 200m² roof would require: 200 × 0.0125 = 2.5m³ of soakwell volume. However, always check with your local council as they may have specific requirements. Try the soakwell calculator tool for easy calculations.

Each Perth council has specific minimum distances, but generally soakwells must be at least 1.5-1.8 metres from footings and boundaries. However, safe excavation requires considering the angle of repose - the safe distance from a footing equals the depth of the hole. For example, a 1200mm deep soakwell needs approximately 1650mm clearance from footings (1200mm + 150mm cover + 300mm backfill).

No, each council has specific regulations and formulas. While all must comply with Australian Standard AS3500.1/3, individual councils like Armadale, Bayswater, Belmont, Canning, Cockburn, Joondalup, Perth, Swan, Victoria Park, and Wanneroo have their own stormwater management requirements. Use our council selector tool on this page to view regulations specific to your area.

Not installing adequate soakwells violates Western Australian building regulations. Without proper stormwater management, you risk: 1) Water damage to your property and neighbouring properties, 2) Potential legal liability for stormwater runoff onto neighbouring land, 3) Building approval issues if selling or renovating, and 4) Contributing to local flooding and drainage problems. Council-compliant soakwells ensure your system can handle storm events without damage.