Indiana Administrative Code
Title 327 - WATER POLLUTION CONTROL DIVISION
Article 8 - PUBLIC WATER SUPPLY
Rule 2.5 - Disinfectants and Disinfection
Section 2.5-14 - Reduced monitoring; stage 2 disinfection byproducts requirements
Current through March 20, 2024
Authority: IC 13-13-5; IC 13-14-8-7; IC 13-14-9; IC 13-18-3-2; IC 13-18-16
Affected: IC 13-18-3-11
Sec. 14.
(a) A PWS may reduce monitoring for stage 2 disinfection byproducts to the monitoring frequency specified in the following table if the following are met:
Table 14
Source Water Type | Population Size Category | Monitoring Frequency1 | Distribution System Monitoring Location per Monitoring Period |
Subpart H | < 500 | Monitoring cannot be reduced. | |
500-3,300 | per year | One (1) TTHM and one (1) HAA5 sample; one (1) at the location and during the quarter with the highest TTHM single measurement; one (1) at the location and during the quarter with the highest HAA5 single measurement; one (1) dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. | |
3,301-9,999 | per year | Two (2) dual sample sets; one (1) at the location and during the quarter with the highest TTHM single measurement; one (1) at the location and during the quarter with the highest HAA5 single measurement. | |
10,000-49,999 | per quarter | Two (2) dual sample sets at the locations with the highest TTHM and highest HAA5 LRAAs. | |
50,000-249,999 | per quarter | Four (4) dual sample sets at the locations with the two (2) highest TTHM and two (2) highest HAA5 LRAAs. | |
250,000-999,999 | per quarter | Six (6) dual sample sets at the locations with the three (3) highest TTHM and three (3) highest HAA5 LRAAs. | |
1,000,000-4,999,999 | per quarter | Eight (8) dual sample sets at the locations with the four (4) highest TTHM and four (4) highest HAA5 LRAAs. | |
>= 5,000,000 | per quarter | Ten (10) dual sample sets at the locations with the five (5) highest TTHM and five (5) highest HAA5 LRAAs. | |
Ground water | < 500 | every third year | One (1) TTHM and one (1) HAA5 sample; one (1) at the location and during the quarter with the highest TTHM single measurement; one (1) at the location and during the quarter with the highest HAA5 single measurement; one (1) dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. |
500-9,999 | per year | One (1) TTHM and one (1) HAA5 sample; one (1) at the location and during the quarter with the highest TTHM single measurement; one (1) at the location and during the quarter with the highest HAA5 single measurement; one (1) dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. | |
10,000-99,999 | per year | Two (2) dual sample sets; one (1) at the location and during the quarter with the highest TTHM single measurement; one (1) at the location and during the quarter with the highest HAA5 single measurement. | |
100,000-499,999 | per quarter | Two (2) dual sample sets at the locations with the highest TTHM and highest HAA5 LRAAs. | |
>= 500,000 | per quarter | Four (4) dual sample sets at the locations with the two (2) highest TTHM and two (2) highest HAA5 LRAAs. |
1Systems on quarterly monitoring must take dual sample sets every ninety (90) days.
(b) A PWS may remain on reduced monitoring if the following requirements, as applicable, are met:
(c) A PWS shall cease reduced monitoring and resume routine monitoring under section 12 of this rule or begin increased monitoring under section 16 of this rule if one (1) or more of the following occurs:
(d) The commissioner may return a PWS to routine monitoring at the commissioner's discretion.