Virginia Law

A. An underground water storage unit for a rainwater harvesting system shall be sited with appropriate consideration given to distance from potential contamination sources, vulnerability to known or suspected natural risks (e.g., flooding and sink holes), potential for interference with utilities, and safety.

B. If the rainwater harvesting system will include an underground installation of a water storage unit, the designer shall conduct a sanitary survey, including investigation of obvious sources of toxic or dangerous substances within 200 feet of the water storage unit. Sources of contamination may include items listed in Table 1. The minimum separation distance between an underground water storage unit and sources of contamination shall comply with the minimum distances shown in Table 1.

C. An aboveground water storage unit shall be installed on a sturdy and level foundation or platform with adequate drainage capable of bearing the weight of the unit at capacity. If multiple storage units are connected, compliant fittings must be used and installed in a manner that provides adequate flexibility to allow for unit settlement or movement.

D. A water storage unit and associated pipes and pipe fittings and appurtenances to be installed in locations subject to direct sunlight shall be constructed of materials stable under ultraviolet light exposure anticipated over the life of the system.

E. A water storage unit shall be supported and restrained to prevent lateral movement. Support and restraint devices may not be placed in a manner that will obstruct access for cleaning and maintenance.

F. A water storage unit subject to a shallow water table shall be ballasted or otherwise secured to prevent floatation or lateral movement. The unit shall be designed to withstand structural stresses of hydrostatic pressure and buoyancy. If partially buried, design shall include provision to withstand the weight of backfill.

G. A water storage unit subject to vehicular traffic shall be installed in accordance with manufacturer's installation instructions and the USBC.

H. A water storage unit shall have at least one access opening to allow inspection and cleaning of the unit interior. The access opening shall be located to facilitate pumping and servicing of inlets and outlets. The access opening shall be locked or otherwise secured to prevent unauthorized access and shall be located at a finished grade such that surface water ponding does not occur under annual precipitation extreme conditions.

I. A water storage unit shall be fitted with an overflow discharge system with the following requirements:

1. Overflow is not less than the capacity of the inlets;

2. Unit overflow pipes are protected from insects and vermin;

3. Piping associated with unit overflow discharges water away from the unit and in accordance with the USBC;

4. Discharge of unit overflow is directed to prevent hazardous conditions;

5. No shutoff valves are incorporated into discharge piping;

6. Cleanouts are provided on overflow piping in accordance with the USBC;

7. If connected to storm drainage systems, the storm drainage systems have a means to prevent backflow; and

8. Overflows are not directed to onsite sewage systems or sanitary sewers.

J. A water storage unit shall be fitted with a vent pipe having a minimum 38.1 mm diameter protected with 1.5 mm mesh to prevent the entry of vermin and particulates.