12VAC5-635-260. Disinfection.
A. The owner shall ensure that harvested rainwater intended for Tier 2, 3, or 4 end use is disinfected and that water meeting the quality standards in 12VAC5-635-310 is delivered to the point of use.
B. The owner shall ensure that disinfection systems are designed and installed in accordance with the manufacturer's instructions and the USBC.
C. If a rainwater harvesting system requires a disinfection system pursuant to this section, the owner shall use one of the following acceptable methods:
1. An ultraviolet (UV) disinfection system that (i) treats water for distribution downstream of the water storage unit and upstream of the point of use; (ii) is sized based on the required dose, taking into consideration the design flow and minimum UV transmittance required to achieve the end use tier standard; and (iii) for Tier 4 end use, is labeled to be certified to Class A of NSF 55;
2. An ozone disinfection system that maintains adequate contact time based on end use tier and off-gasses to a safe environment; or
3. A chemical system that:
a. Has means to measure and control the disinfection and oxidation levels to achieve the performance requirements in 12VAC5-635-310;
b. Uses chemical feed pumps that are controlled to prevent operation unless there is flow through the system;
c. Is labeled to be certified to provide the required log reductions for protozoa and bacteria pursuant to NSF 53 or is labeled to be certified to provide the required log reductions for protozoa and bacteria pursuant NSF/ANSI 419-2018;
d. Uses chemicals that are labeled to demonstrate compliance with NSF/ANSI/CAN Standard 60-2020 if water is provided for Tier 4 end use; and
e. Maintains a chlorine residual of at least 0.5 mg/L and control disinfection byproducts if untreated harvested rainwater is stored at temperatures higher than 77°F and chlorine disinfection is used.
D. A rainwater harvesting system for end use in a single-family home shall only use ultraviolet or ozone disinfection methods.
E. The department may approve other disinfection methods on a case-by-case basis.
Statutory Authority
§§ 32.1-12 and 32.1-248.2 of the Code of Virginia.
Historical Notes
Derived from Virginia Register Volume 41, Issue 5, eff. November 20, 2024.