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Certified Backflow Prevention, Testing & Installation in Toronto & the GTA

If you own a commercial, industrial, or multi-unit property, Toronto's Water Supply By-law requires a tested backflow preventer and the fines for non-compliance can exceed $100,000. We install, test, and certify your device, and file the paperwork with the City. CCCS/OWWA certified. Free consultation.

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DrainCom is the

No. 1 Rated

choice for licensed and insured basement waterproofing services in Mississauga, Canada.

Backflow prevention is a certified, regulated job ; not general plumbing. Our cross-connection control specialists are OWWA-certified, and we handle the whole thing: hazard survey, the right device to code, installation, certified testing, and filing your report with the City. You stay compliant. The paperwork’s off your plate.

20+ years across Toronto and the GTA :- restaurants, condos, industrial sites, institutions, multi-residential buildings, and homes with a hazard like irrigation or a boiler. Licensed, insured, certified, and clear on cost.

Call us at 905-238-6800

for a free backflow consultation and quote, or fill out the request form at the top of this page.

What Property Owners Say About DrainCom

Backflow Prevention Services We Provide

We handle backflow prevention end to end for commercial, industrial, institutional, and multi-residential properties across the GTA. Every job is done by a certified cross-connection control specialist.

Commercial backflow prevention assembly with pressure gauges and clear check valve housings

Backflow Hazard Survey

The first step. We assess your plumbing, water use, and cross-connections to set your hazard level  and confirm whether the City requires a reduced pressure (RP) device or a double check valve assembly (DCVA). Toronto wants this survey updated at least every five years.

Backflow Preventer Installation (RPZ & DCVA)

We supply and install the right device  sized to code and your hazard level  in an accessible, compliant spot, with the isolation valves, supports, and relief drainage an RP device needs. We follow City standard details, so it passes its first test and meets the by-law.

Certified Annual Backflow Testing

Toronto requires every device tested at install, once a year, and within 72 hours of any repair. Our certified specialists test with a calibrated gauge, tag the device, and document the result so you never miss a deadline.

Backflow Device Repair & Replacement

Fail a test and the device has to be fixed or replaced to stay compliant. We carry rebuild kits and replacement assemblies, repair or swap the unit, and retest within the City’s 72-hour window —so your compliance never lapses.

Permits & City Report Filing

The part most property owners dread. We pull the City of Toronto backflow permit per device, submit your test report on the City’s forms through the program portal, and keep your records straight. The whole compliance trail, handled.

Fire-Line Backflow Prevention

Fire systems follow the same rules as your domestic water :- commissioning, annual testing, filed reports, often with detector assemblies (RPDA or DCDA). We test and certify fire-line devices, so your system stays compliant and your insurance stays valid.

Backflow Prevention Cost

Cost depends on the device type and size, your hazard level, site access, and how many devices your property needs. RP/RPZ assemblies cost more than DCVAs but are required for severe hazards. Here’s how the pieces break down  itemized, the way the City’s own paperwork splits them.

Item Typical Cost (CAD) Notes
Backflow device + installation Quoted on survey Depends on device type (RPZ/DCVA), size, and access
City of Toronto permit (per device) ~$89.22 Set by the City; required per device installed or replaced
Certified annual test (per device) $120 to $250 Required at install, yearly, and within 72h of any repair
Repair / rebuild Quoted on inspection Rebuild kit or replacement assembly
Fire-line testing Quoted on inspection Detector assemblies (RPDA / DCDA)

All prices are approximate. Device and installation costs are quoted after the hazard survey, since the device type and size depend on your property. We give you an itemized quote device and install, permit, and testing as separate lines  so you can compare bids fairly.

Pricing note: The biggest cost factor is the device type, and that’s set by your hazard level, not by us. A severe-hazard property (chemicals, certain industrial or medical uses) requires an RP/RPZ assembly; a moderate-hazard property can use a DCVA, which costs less. The hazard survey determines which you need  we don’t upsell you into a device the City doesn’t require.

What Is Backflow and Why Does It Matter?

Backflow is the unwanted reversal of water flow in a plumbing system, which can pull contaminated or non-potable water back into the clean drinking water supply. A backflow preventer stops it, keeping water flowing one way only.

It happens two ways. Back pressure  pressure on your side rises above the city supply (a boiler, a pump, a temperature change) and pushes water backward. Back siphonage  the city supply pressure drops (a water-main break, a hydrant opening nearby) and siphons water out of your building. Either way, contaminants from irrigation, industrial processes, or equipment can reach the public water supply. That’s why the City regulates it.

Do You Need a Backflow Preventer? (Toronto By-law Requirements)

Under the City of Toronto’s Water Supply By-law (Chapter 851), backflow prevention is mandatory for many properties. You need a tested device if you own:

  • An industrial, commercial, or institutional (ICI) property
  • A multi-residential building with 5 or more units (Part 3 residential)
  • A construction site drawing on the city supply
  • A residential property with a specific hazard -such as an irrigation system with chemical injection, a boiler, or other cross-connection

Most single-family homes are exempt unless a hazard like the above exists. Not sure where you stand? A hazard survey settles it  and with by-law fines that can exceed $100,000, it’s worth confirming.

Backflow Preventer vs. Backwater Valve - What's the Difference?

These get confused constantly, and they’re not the same thing.

A backflow preventer goes on your clean water supply line and stops contaminated water from reversing into the drinking water , a water-quality and compliance device. A backwater valve goes on your sewer line and stops sewage from backing up into your basement during a storm  a flood-prevention device. Different problem, different device, different location.

If your concern is a basement that floods or backs up in heavy rain, that’s the backwater valve, not backflow prevention. (See Backwater Valve Installation  and that work may qualify for a city flood-protection rebate.)

Brass backflow prevention assembly mounted on a brick exterior wall with copper piping
Backflow prevention diagram comparing clean forward flow with contaminated water being dumped

Our Backflow Compliance Process

We handle the whole compliance trail so you don’t have to chase it.

  • Hazard survey — we assess your plumbing and cross-connections and confirm your hazard level.
  • Device selection — we size and specify the right device (RPZ or DCVA) to code.
  • Permit — we pull the City of Toronto backflow permit for each device.
  • Installation — we install to City standard details, accessible and compliant.
  • Certified test — our specialist tests with a calibrated gauge and tags the device.
  • Report filing — we submit your test report on the City's forms and keep your records.
  • Annual reminders — we track your next test date so you never fall out of compliance.

RPZ vs. DCVA - Which Device Does Your Property Need?

The device is set by your hazard level, following CSA B64 and the City’s schedules. Here’s the short version.

A DCVA (Double Check Valve Assembly) is required when

your property is moderate hazard the potential backflow is a nuisance, not a health risk. Two check valves, the second backing up the first. Common for many commercial and multi-residential buildings.

An RP / RPZ (Reduced Pressure Zone Assembly) is required when

your property is severe / high hazard where backflow could carry a health risk (chemicals, certain industrial, medical, or irrigation-with-injection uses). It offers the strongest protection and is required wherever contamination risk is serious. Note: an RP device can't be installed below grade in a pit, and its relief outlet must drain to a sanitary sewer.

The hazard survey decides which one applies. We confirm it, install to code, and certify the device.

Get Your Property Compliant →

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Frequently Asked Questions

Industrial, commercial, and institutional (ICI) properties, multi-residential buildings with 5 or more units, and construction sites must have a tested device under the Water Supply By-law. Single-family homes are usually exempt unless there’s a specific hazard, like an irrigation system with chemical injection or a boiler.

In Toronto, every device must be tested at installation, once every year, and within 72 hours of any repair or service. Only a certified Cross-Connection Control Specialist can perform the test and file the report with the City  which is what our certified team does.

A DCVA (double check valve assembly) is for moderate-hazard properties  two check valves, one backing up the other. An RP or RPZ (reduced pressure zone assembly) is for severe-hazard properties where backflow could carry a health risk. Your hazard level decides which the City requires.

A backflow preventer protects your clean water supply from contamination. A backwater valve protects your basement from sewage backing up the drain during a storm. Different devices, different jobs  backflow is on the water line, backwater is on the sewer line.

Non-compliance with the Water Supply By-law can bring fines that exceed $100,000, and you carry liability if contamination occurs. A missed annual test puts you out of compliance, which is why we track your test dates and file your reports on time.

Yes. We pull the City of Toronto backflow permit for each device, submit your test reports on the City’s forms, and keep your records. The whole compliance trail is handled for you.

Yes. Our cross-connection control specialists are OWWA-certified with calibrated test gauges, which is the qualification the City requires to test devices and file reports. We’re licensed, insured, and certified for the work.

Usually not  most single-family homes are exempt. The exception is a specific hazard, such as an irrigation system with chemical injection or certain boilers. If you’re unsure, we’ll assess it and tell you whether the City requires a device.

Check the service area list on this page for your city. We cover communities across the GTA. Call 905-238-6800 or 416-989-5757, or submit the contact form at draincom.ca. We confirm availability for most service areas quickly.

Indoor RPZ backflow prevention assembly with test tag on copper pipes in a utility room

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