12VAC5-635-310. Water quality standards.

A. The owner shall perform initial water quality testing before the use of water from the rainwater harvesting system and subsequent water quality sampling and testing consistent with the schedule in 12VAC5-635-320 and in accordance with the operation and maintenance manual requirements of this chapter.

B. The owner shall:

1. Flush the system at least once with treated harvested rainwater before water quality testing and discharge the flush water as wastewater;

2. Collect samples for water quality testing from a point-of-use outlet intended for regular use, such as a kitchen sink;

3. Collect first draw samples of one liter for lead testing;

4. Ensure that water quality samples are analyzed by a laboratory certified by the Division of Consolidated Laboratory Services for drinking water samples; and

5. Ensure that the water is tested in accordance with the minimum performance criteria in Tables 3 and 4 and, at minimum, for total coliform or E. coli present, total nitrate and nitrite content, pH, and lead content.

TABLE 3 Minimum Performance Requirements
Application				Log Reduction Target
End Use Tier	Category	Potential for Human Contact	Example Use	Viruses	Bacteria	Protozoa	pH
1	Nonpotable	Low	Trap primers Spray irrigation (restricted access) Surface and subsurface irrigation Ice rinks	0*	0	0	N/A
2	Nonpotable	Medium	Toilet and urinal flushing Clothes washing HVAC evaporative cooling Rooftop thermal cooling	0*	2 log	2 log	N/A
3	Nonpotable	High	Hose bibs Pressure washing Decorative fountains Vehicle washing Spray irrigation (nonrestricted access) Firefighting or protection and fire suppression	0*	3 log	3 log	N/A
4	Potable	High	Human consumption	0*	6 log	6 log	7-10.5
* It is unlikely that human infectious viruses are present in harvested rainwater. However, if underground water storage tanks are used where there is a potential for sewage contamination or surface water infiltration, a 4-log reduction for viruses shall be required.

TABLE 4 Requirements for Tier 4 Potable Water
Design Standards
Filtration	5 µm
Disinfection	40 mi/cm² and labeled certified to Class A of NSF/ANSI 55
Water Quality Parameters
Turbidity	<0.3 NTU
Lead	<15 µg/L
Nitrates	<10 µg/L

C. Before the commissioner issues an operation permit for a rainwater harvesting system intended for Tier 4 use, the owner must document that the treated harvested rainwater has been tested and meets primary U.S. Environmental Protection Agency drinking water standards (inorganic), the tests listed in subdivision B 5 of this section, and the tests listed in Table 4. If a primary drinking water standard or design standard is exceeded, the owner may provide additional treatment to address the exceedance and shall resample the treated harvest rainwater to ensure compliance with this subsection. Testing for inorganic primary drinking water standards shall not be required for subsequent monitoring unless specified in the operation and maintenance manual prepared pursuant to 12VAC5-635-350.

D. The owner shall conduct water quality sampling and monitoring in accordance with the procedures approved under 40 CFR Part 136 or alternative methods approved by the department, unless other procedures have been specified in this chapter.

E. The designer shall identify the rainwater harvesting system's water quality sampling points, which shall be downstream of the treatment steps and upstream of the point of use. If total residual chlorine is used to measure compliance in a system using chlorine disinfection, the sampling point must be downstream of the chlorine contact tank. If ultraviolet (UV) disinfection is used, the owner may not use water samples collected upstream of UV disinfection units for dosage adjustment for the purposes of water quality testing pursuant to this section.

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.

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