Toronto Backflow Prevention Program

Understanding Toronto's Backflow Prevention Program

The City of Toronto enacted the Water Supply Bylaw, which includes the Backflow Prevention Program, to protect the municipal water supply from contamination. Backflow occurs when water reverses direction and flows from a property back into the municipal system, potentially carrying contaminants. Non-compliance penalties can exceed $100,000, making adherence critical for property owners.

Two mechanisms cause backflow: back pressure, where increased pressure in on-property systems forces water backward due to boiler temperature spikes, elevated tanks, or pumps; and back siphonage, where sudden drops in municipal supply pressure draw water backward during water main breaks or high-volume draws.

Who Needs to Comply?

Industrial, commercial, institutional facilities, and residential buildings exceeding five units sharing a single water connection must comply with the program. Properties are classified by risk level:

• Low risk: Single-family homes and small retail operations
• Moderate risk: Hotels, apartments, kennels, dental clinics, nursing homes, grocery stores -- require double check valve assemblies
• Severe risk: Chemical plants, hospitals, refineries, car washes, beverage manufacturing -- require reduced pressure principle devices

Most single-family residences are exempt from the program due to their low-risk classification. However, homes with auxiliary water supplies such as wells may need assessment and devices installed.

Maintenance Obligations

Property owners must conduct annual device testing, regular maintenance surveys, and maintain comprehensive records through certified backflow technicians. Most municipalities require testing results to be submitted annually via online forms.

Backflow vs. Backwater: What is the Difference?

While the terms sound similar, they address different problems. Backflow involves water reversing from your property into the municipal supply, creating a contamination risk. Backwater refers to sewage or storm drain water backing up through your building drains, causing flooding and contamination inside your property. Backwater valves use hinged doors to block reverse flow from sewers or storm drains.

How We Help

At Absolute Draining & Plumbing, our certified specialists review your water supply systems and cross-connection risks, install the appropriate backflow prevention devices, and manage all compliance documentation. We handle annual testing, submit results to the municipality, and ensure your property remains in full compliance with Toronto's requirements.