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.
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, please use the Report a Concern form or contact us at Engineering@MapleRidge.ca or 604-467-7339.
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.
On the day of the fog testing, staff will install fans at maintenance holes to push the fog through the sanitary sewer system. They will observe where the fog exits the system; generally, the fog will exit the system through maintenance holes, parking lot drains, and sanitary sewer vent stacks on the roofs of properties.
If the fog enters your property, it means a p-trap in your property is empty or there is a defect in your private sanitary or drainage connection. Please notify the City by calling 604-467-7339.
The fog is not harmful—it is safe for people, animals, and plants and will not leave a residue behind. Open doors and windows and move outside until it dissipates.
How to Prepare
To keep the fog within the sanitary sewer system and prevent it from entering your building, ensure all p-traps in drains are filled with water.
P-traps are bends in the plumbing system that are usually filled with water, preventing the backflow of sewage gases into your building. If a drain is seldom used, the water in the p-trap can evaporate over time. Before the fog testing, pour at least four cups of water down any seldom-used drains to ensure the p-traps are full.
Report Fog Entering Your Property
If fog enters your property during testing, notify us by calling 604-467-7339. The fog is not harmful and will dissipate naturally.