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Virginia Administrative Code
Title 9. Environment
Agency 25. State Water Control Board
Chapter 790. Sewage Collection and Treatment Regulations
12/21/2024

9VAC25-790-740. Disinfection.

Article 7
Effluent Polishing and Disinfection Processes

A. Disinfection processes are designed to inactivate actual or potential pathogenic microorganisms present in treated sewage effluents. Disinfection of treated sewage effluents shall be provided to prevent the occurrence of public health hazards in either receiving streams, land treatment sites, or reuse applications from wastewater effluents. Disinfection shall be accomplished in a manner that meets standards for indicator microorganisms but does not result in a violation of toxicity standards.

B. Policy. The need for disinfection of a sewage treatment works effluent is primarily based on standards for either the receiving waters and the land application site or public exposure to reuse as determined by the following requirements:

1. Discharges located within 15 miles upstream or one tidal cycle downstream of a water supply intake shall be disinfected at all times.

2. When sewage discharges are permitted to or within five miles upstream of shellfish waters, they shall be disinfected at all times.

3. Discharges located in all other waters shall be disinfected at all times unless it can be demonstrated, through the use of a Site Specific Beneficial Use-Attainability Analysis of the recreational and other beneficial seasonal uses of the receiving stream, that disinfection is not needed throughout the year, or on a seasonal basis, to protect those uses.

4. Discharges for land treatment or reuse purposes shall be disinfected as necessary to protect the public health and welfare. The public shall not be directly exposed to treated effluent.

C. Toxicity reduction. The need for reducing the effect of toxicity from wastewater effluents is based on the characteristics of the discharge and receiving stream and is established at the time of the permit or certificate issuance. Where the need is established, dechlorination or alternate disinfection methods shall be provided.

Statutory Authority

§ 62.1-44.19 of the Code of Virginia.

Historical Notes

Former 12VAC5-581-800 derived from Virginia Register Volume 18, Issue 10, eff. February 27, 2002; amended and adopted as 9VAC25-790-740, Virginia Register Volume 20, Issue 9, eff. February 12, 2004.

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