Inflow and Infiltration
Inflow and infiltration happens when water from the environment enters the sewage system for treatment.
York Region has two sewer systems:
- Sewage system (sanitary sewer)
- Storm sewer
The sewage system is designed to carry sewage to treatment plants for processing before returning it to the environment. The storm sewer prevents streets from flooding by draining and carrying excess stormwater (water from rainfall and snowmelt) to lakes and streams.
What is Inflow and Infiltration and why is it a problem?
What is Inflow and Infiltration?
Inflow and Infiltration happens when water, groundwater and stormwater enters the sewage system through sump pumps, downspouts, and/or holes and cracks in the pipes.
View videos showing common sources of inflow and infiltration in:
Why is Inflow and Infiltration a problem?
Inflow and infiltration are problems because they:
- Reduce the capacity of the sewage system leaving less for existing residents and future growth
- Make sewage treatment less efficient as the sewage is diluted by water
- Increase the cost of water to residents because sewage treatment plants are required to treat a higher volume of flow
- May cause sewage backups in basements
- May overwhelm wastewater treatment plants
Videos are courtesy of Capital Regional District (CRD).
What you can do to prevent inflow and infiltration
There are a few simple things you can do to ensure your property doesn’t contribute to inflow and infiltration.
- Ensure your home’s downspout is disconnected from the sanitary sewer system and flowing properly towards the storm sewer
- Ensure sewer grates on your street are free from debris such as leaves and garbage to ensure storm water drains properly
- Use a rain barrel
- Participate in Regional and City/Town Inflow and Infiltration reduction projects happening in your neighbourhood
The infographic below explains the difference between an incorrect and properly connected downspout.
Current inspection and repair work projects
York Region in partnership with the Towns of Aurora and Newmarket have completed projects that helped to reduce high amounts of rain water, melted snow and groundwater entering the sewer system through inflow and infiltration. Please stay tuned for upcoming 2022 projects.
For questions, please contact Access York at 1-877-464-9675 or email [email protected]
What to expect when inflow and infiltration inspection or repair work is happening in your neighborhood
Once a source of inflow and infiltration has been found, York Region and/or local cities and towns begin repair projects which may include:
- Repairing defects such as cracks or holes in pipes
- Disconnecting known inflow sources, such as downspouts from the sewage system
- Reviewing and updating construction design standards
- Developing new standards and guidelines for inspecting and testing the sewage system
Trenchless technology is used to repair or replace pipes with minimal digging or disruption to property. Examples of trenchless technology include:
- Pipe bursting - Replacing an older pipe by sending a new pipe through the old one and “bursting” (destroying) it from the inside
- Relining - Creating an epoxy lining inside of an existing pipe
- Cured-in-place pipe - Creating a pipe within an existing pipe
What York Region is doing about inflow and infiltration
Finding and reducing inflow and infiltration is a high priority. It reduces the cost of treating stormwater water as sewage, helps to maintain and extend the life of costly infrastructure and helps to ensure there is enough capacity for wastewater to move through the system.
Finding Sources of Inflow and Infiltration
York Region monitors rainfall and the sewage system to find areas with higher than expected water flow.
York Region and/or local cities and towns further investigate on-site by using mobile video cameras to perform a closed circuit television inspection. Learn more about how we monitor for inflow and infiltration.
We may further investigate sources through forcing vegetable based, non-toxic, odourless smoke into sewer maintenance holes or adding a non-toxic dye to an upstream freshwater source believed to be contributing to inflow and infiltration.
Reducing Inflow and Infiltration
Once a source of inflow and infiltration has been found, York Region or local towns and cities inspect and repair issues in manholes and sewer lines, reducing inflow and infiltration in the community’s sewage system.
York Region also proactively applies inflow and infiltration reduction practices into the design and construction of new sewer systems and rehabilitation projects, ensuring new infrastructure is monitored right from the beginning. View full details on Sanitary Sewer System Inspection, Testing and Acceptance Guidelines.
What local cities and towns are doing about inflow and infiltration
Current local municipal initiatives happening in York Region:
- Flood Control Program in the City of Markham
- Inflow and Infiltration Reduction Program in the City of Vaughan
- Basement Flooding in the Town of Aurora
Please visit your local municipality’s website to learn about activities in your area.
- White Paper - Inflow and Infiltration in New Developments: A York Region Perspective
- 2021 Inflow and Infiltration Reduction Strategy Update
- 2020 Inflow and Infiltration Annual Report
- Inflow and infiltration Best in Class Review
- Inflow and Infiltration Reduction Strategy
- 2016 Inflow and Infiltration Reduction Strategy Update
- Long Term Water Conservation Strategy
- Sanitary Sewer Inspection Testing and Acceptance Guideline
- Additional Environment Resources