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DEFINITIONS (FROM CSA B64.10.11)

Backflow: the reversal of the normal direction of the flow of water.

Backflow preventer: a device that prevents backflow.

Backflow prevention device tester: a person who is certified to test backflow preventers by an accredited organization acceptable to the regulatory authority.

Cross-connection: any actual or potential connection between a potable water system and any source of pollution or contamination.

Note: Bypass arrangements, jumper connections, removable sections, swivel or changeover devices, or any other temporary or permanent connecting arrangements through which backflow can occur are considered cross-connections.

Owner: any person, firm, or corporation having control over property to which this Bylaw

Potable water: water safe for human consumption.

QUESTIONS & ANSWERS

WHAT IS “BACKFLOW PREVENTION” ENGINEERING?

Backflow prevention engineering, a discipline dedicated to averting the flow of contaminated water into a drinking water supply.

Question: What are the most common causes of contamination of drinking water?

Answer: a) Back siphonage: the reversal of the normal flow of water caused by a depression in the supply system and b) Back pressure: the reversal of the normal flow of water caused by a pressure higher than the supply pressure.

What can cause a back siphonage?

Answer: Back siphonage can be caused by the public water supply system; interruption of service, broken pipes, the use of many fire hydrants, etc.

What can cause a back pressure?

Answer: A back pressure can be observed when the pressure downstream is greater than the pressure upstream in a piping system. For example, we experience this phenomenon when a heating or fire protection system is equipped with a circulator or a booster pump. If these equipments are used during a pressure drop in the public water supply system, the high pressure of the pump could reverse the normal flow of water.

DRINKING WATER CONTAMINATION CASES

PARTICLE FOUND IN DRINKING WATER AT SAINTE-JUSTINE HOSPITAL

In January 2016, the Sainte-Justine hospital was obliged to ban drinking water consumption due to the presence of black particles. Fortunately, these particles proved to be non-toxic to health.

WHAT HAPPENED TO BRING ABOUT THE WALKERTON TRAGEDY?

On May 11, 2000 the water supply of Walkerton, Ontario was contaminated with the O157:H7 strain of E. coli, a life threatening bacteria that evidently entered the water supply from an adjacent well contaminated by farm runoff. The episode resulted directly in the deaths of seven people with an additional 2,500 people contracting illness.

HOW DID DIESEL FUEL ENTER RESIDENTIAL TAP WATER IN LONGUEUIL, QUEBEC?

On January 14, 2015 nearly 28,000 liters of diesel fuel seeped into the ground and St. Lawrence River from a leak in a pump generator. The event left hundreds of thousands of residents without tap water for two days. Allegations of negligence relating to the occurrence led to initiating a class action lawsuit on behalf of effected residents.

WHERE CAN I FIND MORE INFORMATION ABOUT BACKFLOW PREVENTION?

Please visit Backflo Shop’s for answers to your specific questions about the selection, installation and field testing of backflow prevention devices, purchase and calibration of differential pressure gauges as well as technical training.

www.backfloshop.com

Backflo Shop Frequently Asked Questions

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