The CRD’s Core Area Inflow and Infiltration (I&I) Program was created in the early 1990’s as part of the CRD’s Core Area Liquid Waste Management Plan (LWMP).

Inflow and infiltration refers to rainwater and groundwater that enters the sanitary sewer. A certain amount of I&I is unavoidable and is accounted for in routine sewer design. However, when I&I exceeds design allowances, sewer capacity is consumed potentially resulting in: higher conveyance costs; loss of capacity needed for future growth / densification; and sewer overflows that can damage the environment and impact human health.

The goals of the program are to:

  1. Comply with regulatory requirements regarding I&I
  2. Promote the inspection and repair of private property laterals through education.
  3. Prioritize I&I reduction work required to eventually eliminate overflows from the system.
  4. Support sewer asset management programs
  5. Support efforts to maintain sewer capacity needed for future growth, densification, and climate change.


The I&I program supports commitments documented in Section 5 of the core area Liquid Waste Management Plan (LWMP). This section is titled “Management of infiltration and Inflow and Control of Wastewater Overflows”.


The Inflow & Infiltration program reports to a number of committees, including the Core Area Liquid Waste Management Committee and municipal committees. The I&I program also chairs the Core Area I&I sub-committee, which is comprised of representatives from the CRD, Colwood, Esquimalt, Langford, Oak Bay, Saanich, Victoria, and View Royal and meets multiple times per year.


The Inflow & Infiltration program is funded through North West Trunk and North East Trunk – Clover operating budgets. These operating budgets are recovered from participating municipalities based on annual sewer flows.