California Code of Regulations
Title 22 - Social Security
Division 4 - Environmental Health
Chapter 15.5 - Disinfectant Residuals, Disinfection Byproducts, and Disinfection Byproduct Precursors
Article 3 - Monitoring Requirements
Section 64534.4 - Disinfectant Residuals Monitoring

Universal Citation: 22 CA Code of Regs 64534.4

Current through Register 2024 Notice Reg. No. 38, September 20, 2024

(a) Community and nontransient noncommunity water systems that use chlorine or chloramines shall measure the residual disinfectant levels at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in sections 64423, 64424, and 64425. Systems using approved surface water may use the results of residual disinfectant concentration sampling conducted under section 64656, in lieu of taking separate samples.

(b) Public water systems that use chlorine dioxide shall monitor for chlorine dioxide daily at the entrance to the distribution system. For any daily sample that exceeds the MRDL, the system shall take three chlorine dioxide distribution system samples the following day, as follows:

(1) If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used to maintain a disinfectant residual in the distribution system and there are no disinfection addition points after the entrance to the distribution system (i.e., no booster chlorination), the system shall take three samples as close to the first customer as possible, at intervals of at least six hours; and

(2) If chlorine is used to maintain a disinfectant residual in the distribution system and there are one or more disinfection addition points after the entrance to the distribution system (i.e., booster chlorination), the system shall take one sample at each of the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the furthest customer as possible (reflecting maximum residence time in the distribution system).

1. New section filed 5-18-2006; operative 6-17-2006 (Register 2006, No. 20).
2. Amendment of subsections (b)-(b)(2) and NOTE filed 5-22-2012; operative 6-21-2012 (Register 2012, No. 21).
3. Amendment of subsection (a) and amendment of NOTE filed 5-28-2021; operative 7-1-2021 (Register 2021, No. 22).

Note: Authority cited: Sections 116271, 116350 and 116375, Health and Safety Code. Reference: Sections 116350, 116385 and 116555, Health and Safety Code.

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