SECTION P-714  BACKWATER VALVES
P-714.1 Sewage backflow. Where plumbing fixtures are installed on a floor with a finished floor elevation below the fresh air inlet termination elevation of the manhole cover of the next upstream manhole in the public sewer, such fixtures shall be protected by a backwater valve installed in the building drain, or horizontal branch serving such fixtures. Plumbing fixtures installed on a floor with a finished floor elevation above the elevation of the fresh air inlet termination manhole cover of the next upstream manhole in the public sewer shall not discharge through a backwater valve. Exception: In existing buildings, fixtures above the elevation of the fresh air inlet termination manhole cover of the next upstream manhole in the public sewer shall not be prohibited from discharging through a backwater valve.
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