Maple Ridge conducting fog testing for sewer system maintenance
Published 5:00 am Wednesday, April 22, 2026
Residents might see a vapour seeping from storm drains or roof vents in coming days.
The City of Maple Ridge will be conducting fog testing in select neighbourhoods as part of its ongoing infrastructure maintenance program.
Fog testing helps maintain sewer system capacity, prevents backups and overflows during heavy rainfall, protects the environment, and reduces sewage treatment costs.
The sanitary sewer system collects wastewater and transfers it to Metro Vancouver’s sewage system for treatment. Stormwater, including rainwater and groundwater, is managed separately and must not enter the sanitary sewer system.
Stormwater entering the sanitary sewer system is known as “inflow and infiltration.” Provincial legislation requires the city to reduce it on public property, and investigate potential sources on private property.
Fog testing involves introducing a non-toxic, visible vapour into the sanitary sewer system to identify where stormwater may be entering through cracks, defects, or improper connections. The vapour is safe, unscented, non-toxic, and non-flammable.
During testing, residents may see vapour coming from roof vents, storm drains, or the ground. This is normal and helps crews identify potential issues.
If testing identifies a problem on public property, the city will address it. If a problem is found on private property, the property owner will be responsible for arranging and paying for repairs.
Residents in affected neighbourhoods will receive advance notice by letter and door hanger before fog testing begins. Before testing, residents should ensure that all drains, especially seldom-used drains, have water in their p-traps (u-shaped pipe under the sink). Pouring at least four cups of water into infrequently used drains will help keep vapour from entering the building.
If fog enters a property, residents should open doors and windows, move outside if needed, and contact the project manager.
This work is in line with industry standards used by other municipalities, says the city.
For more information on fog testing and how to prepare if you receive notification that testing will occur in your neighbourhood, visit MapleRidge.ca/FogTesting.