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.