12VAC5-635-300: Continuity of water supply

A. "Continuity of water supply" means that a continuous supply of water can be provided to a distribution system supplied by a rainwater harvesting system in the event of insufficient precipitation or other circumstances affecting the supply of harvested rainwater.

B. If a rainwater harvesting system serves as a secondary supply for a distribution system and the primary supply is a waterworks, the rainwater harvesting system shall be an auxiliary water system pursuant to the requirements of the USBC and 12VAC5-590.

C. If a rainwater harvesting system serves as a primary supply for a distribution system for a Tier 2, 3, or 4 end use, the owner shall provide a secondary water supply by a waterworks, a Class III private well, or commercially hauled water meeting pure water standards.

D. The owner shall supply a secondary water supply from a waterworks or private well by a means to refill the water storage unit or a bypass that provides water directly to the distribution system.

E. The owner may only use commercially hauled water to refill a water storage unit prior to filtration and treatment.

F. When water from a secondary water supply is added to a water storage unit, the owner shall ensure that the water is introduced through a reverse pressure principle backflow device or an air gap pursuant to the USBC.