BCAB #1799 - Re: Non-Potable Water Systems/Rainwater Harvesting System

July 20, 2017

BCAB #1799

Re: Non-Potable Water Systems/Rainwater Harvesting System

Project Description

The project is a rainwater harvesting system that collects rainwater from a roof surface and is conveyed into two underground tanks. For the purpose of this appeal, the water in the harvested rainwater tank(s) is considered to be non-potable. The water collected is to be used for flushing water closets and for a sub-surface drip landscape irrigation. The water is drawn from the tanks by a pumping unit which detects the level of water. The water supply to the tanks is automatically switched between the harvested rainwater and, in the case of a low level, the building’s potable water system.

The building’s potable water supply to the non-potable system is protected by a reduced pressure principle backflow prevention (RPBP) device. There are two bypass valves immediately after the backflow prevention device that can manually divert water supply directly to the water closet and irrigation lines.

Applicable Code Requirement

Sentence of Division B of the 2012 British Columbia Plumbing Code A non-potable water system shall not be connected to a potable water system.

Decision being Appealed (Local Authority’s Position)

The local authority is not permitting the building’s potable water system to be connected to the non-potable water system. Despite the provision of a RPBP, the bypasses still constitute an interconnection between the potable and non-potable water systems.

Appellant's Position

The appellant considers that the RPBP is more than adequate protection for the building’s potable water supply. Irrigation systems need only be protected by double check valve assembly backflow devices. The higher level of protection provided by a RPBP is more commonly used in hospitals, chemical plants, fertilization operations and other severe hazard applications. The water that is collected off of the roof surface is filtered and is lower risk than the above mentioned hazards. Therefore, the appellant maintains that the manual by-passes should be allowed.

Appeal Board Decision #1799

It is the determination of the Board that the system described interconnects a potable water system with a non-potable water system, which is not permitted.

Reason for Decision

Sentence specifically prohibits connection of a non-potable water system to a potable water system.

Lyle Kuhnert
Chair, Building Code Appeal Board