The sanitary sewer system collects sewage for treatment. Separately, stormwater is collected by the stormwater system and conveyed to nearby watercourses. Discharging stormwater into the sanitary sewer system is prohibited.
Fog Testing in April and May 2026
Fog testing is currently scheduled for two areas in Maple Ridge in April and May 2026, weather permitting. For details, visit MapleRidge.ca/FogTesting.
Sewage is collected in the City’s sanitary sewer system and conveyed to the Annacis Island Wastewater Treatment Plant by Metro Vancouver. Stormwater (rainwater and/or groundwater) is handled in various ways depending on the location and environment: in some areas it’s collected in a storm sewer or ditch and conveyed to a nearby watercourse, in other areas it’s managed on private property using rock pits that allow the water to soak into the ground.
When stormwater enters the sanitary sewer system, it is known as inflow and infiltration (I&I). I&I reduces the capacity of sanitary sewer pipes to convey sewage.
How Does Stormwater Enter the Sanitary Sewer System?
There are two main ways that stormwater can enter our sanitary sewer system:
- Damaged pipes allow groundwater to seep into the sanitary sewer system.
- Improperly connected surface drains allow rainwater to enter the sanitary sewer system.
Correct separation of sanitary and storm sewer systems
Rainwater directed to the sanitary sewer system
Report a Cross Connection
If you know or suspect that your on-site stormwater system is connected to the sanitary sewer system, you can use the Report a Concern form to notify us or contact the fog testing project manager, James Barker:
- James Barker
- 236-613-3821
- JBarker@MapleRidge.ca
How Does Inflow & Infiltration Affect You?
Fog Testing
Provincial legislation requires the City to reduce I&I on public property and investigate I&I on private property. To meet these requirements, the City monitors, inspects, and repairs the public sanitary sewer system and notifies property owners when private plumbing repairs are needed.
One method used to inspect the sanitary sewer system is fog testing, which involves introducing a non-toxic, visible vapour into the sanitary sewer.
When a cross connection on public property is identified by fog testing, it is repaired by the City. When a cross connection is found on private property, property owners are notified and are required to complete repairs.
Fog Testing in Your Neighbourhood
If the City is planning fog testing in your neighbourhood, you will be contacted in advance.
For further information, including current testing locations and how to prepare for fog testing in your neighbourhood, visit our Fog Testing project page.