Iowa Administrative Code › Agency 567 - Environmental Protection Commission › Title II - Air Quality › Division B › Chapter 43 - Water Supplies-design and Operation › Rule 567-43.6 - Residual Disinfectant and Disinfection by Product Precursors

Current through Register Vol. 47, No. 3, July 24, 2024
(1)
Residual disinfectant.
a.
Applicability.
(1) CWS and
				  NTNC systems. This rule establishes criteria under which CWS and NTNC public
				  water supply systems that add a chemical disinfectant to the water in any part
				  of the drinking water treatment process or that provide water that contains a
				  chemical disinfectant must modify their practices to meet the MCLs listed in
				  567-416. (455B), the maximum
				  residual disinfectant levels (MRDL) listed in this subrule, and treatment
				  technique requirements for disinfection byproduct precursors listed in subrule
				  43.6(3).
(2) TNC systems with
				  chlorine dioxide disinfection. This rule establishes criteria under which TNC
				  public water supply systems that use chlorine dioxide as a disinfectant or
				  oxidant must modify their practices to meet the chlorine dioxide MRDL listed in
				  paragraph 43.6(1)
"b. "
(3) Compliance dates. Compliance dates for
				  this rule are based upon the source water type and the population served.
				  Systems are required to comply with this rule as follows, unless otherwise
				  noted:
1. Surface water and IGW CWS and NTNC.
				  CWS and NTNC systems using surface water or groundwater under the direct
				  influence of surface water (IGW) in whole or in part and which serve 10,000 or
				  more persons must comply with this rule beginning January 1, 2002. CWS and NTNC
				  surface water or IGW systems serving fewer than 10,000 persons must comply with
				  this rule beginning January 1, 2004.
2. Groundwater CWS and NTNC. CWS and NTNC
				  systems using only groundwater not under the direct influence of surface water
				  must comply with this rule beginning January 1, 2004.
3. TNC using chlorine dioxide. TNC systems
				  serving over 10,000 persons and using surface water or groundwater under the
				  direct influence of surface water and using chlorine dioxide as a disinfectant
				  or oxidant must comply with any requirements for chlorine dioxide in this rule
				  beginning January 1,2002. TNC systems serving 10,000 persons or less,
				  regardless of source water type, and using chlorine dioxide as a disinfectant
				  or oxidant must comply with any requirements for chlorine dioxide in this rule
				  beginning January 1, 2004.
4.
				  Extension of compliance period for GAC or membrane technology installation. A
				  system that is installing GAC or membrane technology to comply with this rule
				  may apply to the department for an extension of up to 24 months past the dates
				  in 43.6(1)
"a"
(3), but not beyond December 31,2003. In granting
				  the extension, the department will set a schedule for compliance and may
				  specify any interim measures the system must take. Failure to meet a compliance
				  schedule or interim treatment requirements constitutes a violation of the
				  public drinking water supply rules, requires public notification per
				  567-subrule 42.1(1), and may result in an administrative order.
(4) Control of residual
				  disinfectants. Notwithstanding the MRDLs in this rule, systems may increase
				  residual disinfectant levels of chlorine or chloramines (but not chlorine
				  dioxide) in the distribution system to a level and for a time necessary to
				  protect public health, to address specific microbiological contamination
				  problems caused by circumstances such as, but not limited to, distribution line
				  breaks, storm run-off events, source water contamination events, or
				  cross-connection events.
(5)
				  Consecutive systems. Consecutive systems that provide water containing a
				  disinfectant or oxidant are required to comply with this rule.
(6) Systems with multiple water sources.
				  Systems with water sources that are used independently from each other, are not
				  from the same source as determined by the department, or do not go through
				  identical treatment processes are required to conduct the monitoring for the
				  applicable disinfectants or oxidants and disinfection byproducts during
				  operation of each source. The system must comply with this rule during the use
				  of each water source.