LAWN SPRINKLER SYSTEM - BACKFLOW PROTECTION

BRANCH OPINION

LAWN SPRINKLER SYSTEM - BACKFLOW PROTECTION

Sentence 7.6.2.3.(2) requires that a lawn sprinkler system that is connected to the potable water supply be protected from backflow by a backflow preventer.

Sentence 7.6.2.3.(5) states "Backflow prevention devices to protect a potable water system from contamination shall be selected, installed, and field tested in accordance with the CAN/CSA B64.10, 'Backflow Prevention Devices - Selection, Installation, Maintenance, and Field Testing'."

Sentence 7.6.2.3.(6) requires that backflow prevention devices be provided in conformance with Sentence 7.2.9.9.(1). Sentence 7.2.9.9.(1) indicates the appropriate standard that the device must be certified to.

The B64.10 standard does not directly address lawn sprinkler systems. Section 4.2 of the B64.10 standard defines the types of hazards as follows:

minor hazard - any cross-connection or potential cross connection which would constitute only a nuisance, with no possibility that any health hazard could be created;
moderate hazard - any "minor hazard" type cross- connection or potential cross-connection that has a low probability of becoming a "severe hazard";
severe hazard - any cross-connection or potential cross-connection involving any substance that could be an actual danger to health.

A lawn sprinkler system with no chemical injection would be classed as a "moderate hazard". As such, it would require an Atmospheric Vacuum Breaker (AVB), a Pressure Vacuum Breaker (PVB) or a Double Check Valve Assembly (DCVA) in order to be in conformance with the OBC. If an AVB is used, it must not be subjected to continuous pressure.

A lawn sprinkler system with chemical injection would be classed as a "sever hazard". This system would require a Reduced Pressure Principle Type (RP) backflow preventer.

June 9, 1995

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