Is My Property Sub-dividable? Understanding Septic System Requirements for Lot Subdivision on Vancouver Island
If you’re a Vancouver Island homeowner looking to subdivide your rural property, understanding the septic feasibility requirements is essential to the process. Unlike urban settings with access to municipal sewer, rural and semi-rural subdivisions must demonstrate they can support independent, long-term wastewater disposal systems. At Pacific Rim Wastewater Solutions Ltd., we help homeowners navigate the regulatory landscape and determine if their property can support multiple septic systems.
Why Septic System Feasibility is Critical
Before any subdivision is approved, you must prove to the regional district regulators that each new lot can safely and sustainably handle wastewater. This means showing there is suitable space for a primary and a reserve dispersal area on each proposed lot, and that soil and site conditions comply with provincial and local standards. Septic feasibility assessments on Vancouver Island are reviewed by Island Health as part of the subdivision approval process.
Key Regulatory References
Septic system feasibility for subdivisions is governed by several key documents:
BC Sewerage System Regulation (SSR)
BC Sewerage System Standard Practice Manual (SPM V3)
Island Health Subdivision Standards
These guidelines outline the minimum lot size, soil conditions, percolation rates, setbacks, and other design parameters required for subdivision approval.
What’s Required for a Septic Feasibility Assessment?
To assess a property for subdivision, an Authorized Person (such as a registered practitioner or professional) must conduct a comprehensive evaluation. This includes:
Soil Testing & Site Investigation
Excavation of test pits and constant head permeameter testing.
Mapping of soil depth, percolation rates, seasonal high water table, and slope.
Ensuring minimum vertical separation to restrictive layers or groundwater.
Subdivision Layout Planning
Designing primary and reserve dispersal fields.
Aligning system configurations with SPM standards and local setback rules.
Compliance with Island Health Setback Standards:
30 m from wells and permanent water bodies.
15 m from intermittent streams and ephemeral bodies.
3 m from property lines and buildings.
Minimum Lot and Discharge Area Size
For rural lots on private water supply (well water), a minimum of 1.0 ha lot size is typically required.
For rural lots on water supply systems (municipal water), a minimum 0.2 ha lot size is typically required.
Each lot must be capable of supporting a primary standard system (typically Type 1) plus a reserve area for a future system.
The benefit of hiring a Professional Engineer or Geoscientist to conduct these assessments are that we are able to provide expert opinion and recommend strategies to regulatory bodies
Case Example: 3.2 hectare property in Port Alberni
Pacific Rim Wastewater Solutions assessed a 3.20-hectare property for subdivision into three lots of approximately 0.8 ha each. The assessment included excavation of 12 test pits, revealing sandy loam soils with no restrictive layers present, and seasonal high water table at approximately 90 cm. Constant head borehole permeability tests across the site showed a median rate of 4,389 mm/day, equivalent to a percolation rate of 1–2 minutes per inch.
Each lot was deemed suitable for Type 1 septic systems using uniform dispersal to a seepage beds with timed dosing consistent with the SPM V3 requirements. Dispersal areas of 90 m² (3 m x 30 m) were designed, with each lot accommodating both a primary and reserve field.
Water Setbacks: All dispersal fields maintain >30 m from three on-site wells and permanent water features.
Soil Compliance: All three lots met the required 90 cm of native soil above a limiting layer (vertical separation) requirement needed for lots on Private Water Supplies (well water).
Lot 1 Upgrade: The existing septic system for the residence on Lot 1 residence was determined to be undersized, not working as intended and in need of replacement. PRWS recommended replacement within 6 months and prior to subdivision approval.
The sewerage assessment concluded that it was the professional opinion that even though the subdivision deviated from the 1.0 ha minimum lot size, the subdivision would not pose a health hazard due to adequate soil depth and texture, would meet SPM requirements designed to protect underlying aquifers from sewage related contaminants, and would not result in cumulative impacts to adjacent properties or receiving environments.
Conclusion: Plan Ahead with Expert Support
Determining septic suitability is a vital part of the subdivision process in BC. Whether you're planning a two-lot split or a multi-lot rural development, early professional involvement ensures you understand your land's limitations—and potential.
Contact Pacific Rim Wastewater Solutions to schedule a site assessment and learn how we can help guide your subdivision through regulatory approval.