FAQ (Frequently Asked Questions)

Why do I need a "Backflow Prevention Assembly" on my Sprinkler Irrigation System?

The water that is used by your irrigation system is supplied by the same source as the water you drink, cook and bathe with. Pesticides, fertilizers, and/or animal feces can collect in water pooled around your sprinkler heads, creating a potential for the contaminants to be drawn back through the sprinkler irrigation system (by means of backflow or back-siphonage) and into your home. It is for this reason that you must have a properly functioning Backflow Prevention Assembly protecting your drinking water.

Why do I need my "Backflow Prevention Assembly" tested annually?

Backflow Prevention Assemblies and Devices break or wear out, just like the parts of a car. By having your Backflow Prevention Assembly tested annually, you will help to ensure that the drinking water supplied to your home remains safe. Because of this, many lower mainland cities have created this By-law to help ensure the safety of your drinking water. We have Certified Backflow Assembly Testers on staff who have attended rigorous training and are certified by the American Waterworks Association, British Columbia Section, to test your Backflow Prevention Assembly. Certified Testers can inspect, test, repair, or replace all Backflow Prevention Assemblies and Devices.

Why have I never had to test my backflow before?

When your backflow was installed, it was tested prior to plumbing inspection, but because of the volume of Backflow preventers being installed and a large number of existing Backflow preventers in various lower mainland cities, it is not easy for municipalities to keep you informed of when your backflow is due to be tested. However, due to increased awareness of the importance of protecting our water, many cities are taking better steps to inform people when their annual test is due.

What is a cross-connection?

A cross-connection is any temporary or permanent connection between a public water system or consumer's potable (i.e., drinking) water system and any source or system containing non-potable water or other substances. An example is the piping between a public water system or consumer's potable water system and an auxiliary water system, cooling system, or irrigation system.

What is a Backflow preventer?

A Backflow preventer is a means or mechanism to prevent backflow. The basic means of preventing backflow is an air gap, which either eliminated a cross-connection or provides a barrier to backflow. The basic mechanism for preventing backflow is a mechanical Backflow preventer, which provides a physical barrier to backflow. The principal types of mechanical backflow preventers are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical Backflow preventer is the residential dual check valve.

What is an air gap?

An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against back-pressure backflow or back-siphonage but is not always practical and can be easily bypassed

What is a reduced principle (RP) assembly?

An RP is a mechanical Backflow preventer that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RP is effective against back-pressure and back-siphonage and may be used to isolate health or non-health hazards.

What is a pressure vacuum breaker (PVB) assembly?

A PVB assembly is a mechanical preventer that consists of an independently acting, spring-loaded check valve and an independently acting, spring-loaded air inlet valve on the discharge side of the check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A PVB may be used to isolate non-health hazards but is effective against back-siphonage only.

What is a double check valve assembly?

A DCVA is a mechanical Backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DC is effective against back-pressure backflow and back-siphonage but should be used to isolate only non-health hazards.

How much will the test cost, and does the City Charge a fee for Backflow testing?

Our price is $65 for the initial test and $55 for any additional test on the same premises for assemblies up to 1.25" and $85 for 1.5" and above. Some Cities will charge a fee that is additional to the price of the Backflow test. All prices exclude GST


At MDT Backflow, we are committed to educating the public about cross-connection, Backflow prevention, and water protection.
Below are some informative links with general information on Backflow incidents, Backflow assemblies and cross-connection, and the world's water situation.

Public Awareness Resources

Links and articles on Backflow maintenance and organizations and what you can do to help yourself and the local drinking water supply.

International Development Research Centre [Visit]
Resource: Local Solutions to the Global Water Crisis
The International Development Research Centre (IDRC) is a public corporation created by the Parliament of Canada in 1970 to help developing countries use science and technology to find practical, long-term solutions to the social, economic, and environmental problems they face.

Watts Regulator Company [Visit]
Resource: Guide to Stopping Backflow
Watts Regulator Company made its reputation by "Setting The Standard in Valve Technology." During its early days, Watts manufactured pressure-reducing valves to regulate steam and relief valves to ensure the safe operation of water heaters and boilers.

American Backflow Prevention Association [Visit]
The American Backflow Prevention Association (ABPA) is an organization whose members have a common interest in protecting drinking water from contamination through cross-connections. ABPA is an organization dedicated to education and technical assistance.

Vancouver Cross Connection Control Committee [Visit]
The Cross Connection Control Committee was founded in the City of Vancouver in 1971. Key individuals during these early years included George Bratton, Don Currie, Bob Campbell, and Gary Fulton. They began by exploring the significance of backflow and cross-connections within plumbing and water distribution systems on private and municipal property in the Vancouver area.

MDT Backflow - Water Protection

Backflow Incident Examples

Here are a few incidents of damage caused by
improper Backflow maintenance and repair.

Backflow Incident Examples

Here are a few incidents of damage caused by improper Backflow maintenance and repair.

Backflow Products and Accessories

Below we have information on Backflow products and accessories
by some of the top manufacturers in the world.

MDT Backflow - Water Protection

Conbraco [Visit]
Products: Backflow Systems & Accessories
Made in the USA, Conbraco Backflow prevention products are designed for easy installation, servicing, and repair. They also meet applicable ASSE, AWWA, IAPMO, CSA, UL, and USC FCCC & HR performance standards.

MDT Backflow - Water Protection

Watts [Visit]
Products: Plumbing, Heating and Water Quality Products
Watts Water Technology has provided the leading edge in the Backflow system and accessories. From Air Gaps, Caps & Tethers, Vent elbows, Flanges, Spools, and Complete Systems. Watts also provides resources on the prevention of backflow.

MDT Backflow - Water Protection

Zurn [Visit]
Products: Backflow systems and Accessories
The Wilkins Operation of the Zurn Plumbing Products Group specializes in the fields of Backflow prevention and water pressure reduction. Wilkins manufacturers an extensive line of valves for the plumbing, irrigation, and fire protection markets.

Useful Resources

Various non-related websites of interest.

Category: Dynamic websites for businesses (Vancouver)
Responsible for our website, webinfuse.com creates dynamic database-driven websites which allow you to easily and effectively maintain your own content and data without the ongoing costs and time constraints involved with other web developers. These solutions are cost-effectively custom-developed to your needs without using cheap 3rd party content management systems.

The links and references here are strictly for informational purposes only!
MDT Backflow or the webmaster hold no responsibility for the accuracy or content of these links

MDT Backflow - Water Protection