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 64534.2 - Disinfection Byproducts Monitoring
Universal Citation: 22 CA Code of Regs 64534.2
Current through Register 2024 Notice Reg. No. 38, September 20, 2024
(a) Community and nontransient noncommunity water systems shall monitor for TTHM and HAA5 at the frequencies and locations indicated in table 64534.2-A.
Table 64534.2-A Routine and Increased Monitoring Frequency for TTHM and HAA5
| COLUMN A Type of System | COLUMN B Persons served | COLUMN C Minimum monitoring frequency | COLUMN D Sample location in the distribution system & increased monitoring frequencies |
| Systems using approved surface water | >=10,000 | Four samples per quarter per treatment plant | At least 25 percent of all samples collected each quarter at locations representing maximum residence time. Remaining samples taken at locations representative of at least average residence time in the distribution system and representing the entire distribution system, taking into account number of persons served, different sources of water, and different treatment methods1. |
| 500-9,999 | One sample per quarter per treatment plant | Locations representing maximum residence time1. | |
| <500 | One sample per year per treatment plant during month of warmest water temperature | Locations representing maximum residence time1. If the sample (or average of annual samples, if more than one sample is taken) exceeds MCL, system shall increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until system meets reduced monitoring criteria in paragraph (3) of this subsection. | |
| Systems using only ground water not under direct influence of surface water and using chemical disinfectant | >=10,000 | One sample per quarter per treatment plant | Locations representing maximum residence time1. |
| <10,000 | One sample per year per treatment plant during month of warmest water temperature | Locations representing maximum residence time1. If the sample (or average of annual samples, if more than one sample is taken) exceeds MCL, system shall increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the distribution system, until system meets reduced monitoring criteria in paragraph (3) of this subsection. | |
| 1 If a system elects to sample more frequently than the minimum required, at least 25 percent of all samples collected each quarter (including those taken in excess of the required frequency) shall be taken at locations that represent the maximum residence time of the water in the distribution system. The remaining samples shall be taken at locations representative of at least average residence time in the distribution system. | |||
(1) Systems
may apply to the State Board to monitor at a reduced frequency in accordance
with table 64534.2-B. The application shall include the results of all TOC,
TTHM, and HAA5 monitoring conducted in the previous 12 months and the proposed
revised monitoring plan as required by section
64534.8. The State Board will
evaluate data submitted with the application to determine whether or not the
system is eligible for the reduced monitoring specified in table 64534.2-B;
Table 64534.2-B Reduced Monitoring Frequency for TTHM and HAA5
| the system may reduce monitoring if it has monitored at least one | |||
| If the system is a(n)... | serving... | year and... | to this level |
| Approved surface water system which has a source water TOC1 level, before any treatment, [LESS THAN EQUAL TO] 4.0 mg/L | >=10,000 | TTHM1 [LESS THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN EQUAL TO]0.030 mg/L | One sample per treatment plant per quarter at distribution system location reflecting maximum residence time. |
| 500-9,999 | TTHM1 [LESS THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN EQUAL TO]0.030 mg/L | One sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature. | |
| System using only ground water not under direct influence of surface water and using chemical disinfectant | >=10,000 | TTHM1 [LESS THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN EQUAL TO]0.030 mg/L | One sample per treatment plant per year at distribution system location reflecting maximum residence time during month of warmest water temperature. |
| <10,000 | TTHM1 [LESS THAN EQUAL TO]0.040 mg/L and HAA51 [LESS THAN EQUAL TO]0.030 mg/L for the system may reduce monitoring if it has monitored at least one | One sample per treatment plant per three-year monitoring cycle at distribution system | |
| two consecutive years OR TTHM1 [LESS THAN EQUAL TO]0.020 mg/L and HAA51 [LESS THAN EQUAL TO]0.015 mg/L for one year | location reflecting maximum residence time during month of warmest water temperature, with the three-year cycle beginning on January 1 following the quarter in which system qualifies for reduced monitoring. | ||
| 1 TOC, TTHM, and HAA5 values based on annual averages. | |||
(2)
Systems on reduced monitoring shall resume monitoring at the frequency
specified in column C of table 64534.2-A in the quarter immediately following
the quarter in which the system exceeds 0.060 mg/L for the TTHM annual average,
0.045 mg/L for the HAA5 annual average, or 4.0 mg/L for the source water TOC
annual average. For systems using only ground water not under the direct
influence of surface water and serving fewer than 10,000 persons or for systems
using approved surface water and serving fewer than 500 persons, if either the
TTHM annual average is >0.080 mg/L or the HAA5 annual average is >0.060
mg/L, the system shall go to increased monitoring identified in column D of
table 64534.2-A in the quarter immediately following the quarter in which the
system exceeds 0.080 mg/L or 0.060 mg/L for the TTHM and HAA5 annual averages,
respectively; and
(3) Systems on
increased monitoring pursuant to column D of table 64534.2-A may return to
routine monitoring specified in column C of table 64534.2-A if, after at least
one year of monitoring, TTHM annual average is [LESS THAN EQUAL TO]0.060 mg/L
and HAA5 annual average is [LESS THAN EQUAL TO]0.045 mg/L.
(b) Community and nontransient noncommunity water systems using chlorine dioxide shall conduct monitoring for chlorite as follows:
(1) Systems shall take daily samples
at the entrance to the distribution system and analyze the samples the same day
the samples are taken. For any daily sample that exceeds the chlorite MCL, the
system shall take three additional chlorite distribution system samples the
following day (in addition to the daily sample required at the entrance to the
distribution system) at these locations: as close to the first customer as
possible, at a location representative of average residence time, and at a
location reflecting maximum residence time in the distribution system. The
system shall analyze the additional samples within 48 hours of being notified
pursuant to section
64537(b) of the
exceedance;
(2) Systems shall take
a three-sample set each month in the distribution system. The system shall take
one sample at each of the following locations: as close to the first customer
as possible, at a location representative of average residence time, and at a
location reflecting maximum residence time in the distribution system. Any
additional routine sampling shall be conducted in the same manner (as
three-sample sets, at the specified locations). The system may use the results
of additional monitoring conducted under paragraph (1) to meet the monitoring
requirement in this paragraph;
(3)
Systems may apply to the State Board to reduce monthly chlorite monitoring in
the distribution system pursuant to paragraph (2) to one three-sample set per
quarter after one year of monitoring during which no individual chlorite sample
taken in the distribution system has exceeded the chlorite MCL and the system
has not been required to conduct additional monitoring under paragraph (1). The
application shall include the results of all chlorite monitoring conducted in
the previous 12 months and the proposed revised monitoring plan as required by
section 64534.8. The State Board will
evaluate data submitted with the application and determine whether or not the
system is eligible to reduce monitoring to one three-sample set per quarter.
The system may remain on the reduced monitoring schedule until either any of
the three individual chlorite samples taken quarterly in the distribution
system under paragraph (2) exceeds the chlorite MCL or the system is required
to conduct additional monitoring under paragraph (1), at which time the system
shall revert to routine monitoring; and
(4) If a distribution system sample taken
pursuant to paragraph (2) exceeds the chlorite MCL, the system shall take and
analyze a confirmation sample within 48 hours of being notified pursuant to
section 64537(c) of the
exceedance. If the system fails to take a confirmation sample pursuant to this
paragraph, it shall take and analyze a confirmation sample within two weeks of
notification of the results of the first sample.
(c) Community and nontransient noncommunity systems using ozone shall monitor for bromate as follows:
(1) Systems shall take one sample per month
for each treatment plant in the system using ozone. Samples shall be taken at
the entrance to the distribution system while the ozonation system is operating
under normal conditions;
(2)
Systems may reduce bromate monitoring from monthly to once per quarter, if the
system's running annual average bromate concentration is [LESS THAN EQUAL
TO]0.0025 mg/L based on monthly bromate measurements under paragraph (1) for
the most recent four quarters, with samples analyzed using Method 317.0
Revision 2.0, 321.8, or 326.0. The system shall notify the State Board in
writing within 30 days of the change in monitoring frequency; and
(3) Systems shall resume routine bromate
monitoring pursuant to paragraph (1) and notify the State Board in writing
within 30 days of the change in monitoring frequency if the running annual
average bromate concentration, computed quarterly, is greater than 0.0025
mg/L.
(d) By the applicable date specified in section 64530(d), and in lieu of TTHM and HAA5 monitoring in subsection (a):
(1) Community and nontransient noncommunity
water systems shall monitor for TTHM and HAA5 at the frequencies and location
totals indicated in table 64534.2-C and in accordance with the monitoring plan
developed pursuant to section
64534.8;
Table 64534.2-C Routine Monitoring Frequency for TTHM and HAA5
| Minimum monitoring frequency1 | |||
| Source water type | Persons served | Number of distribution system monitoring locations | Monitoring period2 |
| Systems using approved surface water | >=5,000,000 | 20 dual sample sets | per quarter |
| 1,000,000-4,999,999 | 16 dual sample sets | per quarter | |
| 250,000-999,999 | 12 dual sample sets | per quarter | |
| 50,000-249,999 | 8 dual sample sets | per quarter | |
| 10,000-49,999 | 4 dual sample sets | per quarter | |
| 3,301-9,999 | 2 dual sample sets | per quarter | |
| 500-3,300 | 1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement | per quarter | |
| <500 | 1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement3 | per year | |
| Systems using ground water not under direct influence of surface water | >=500,000 | 8 dual sample sets | per quarter |
| 100,000-499,999 | 6 dual sample sets | per quarter | |
| 10,000-99,999 | 4 dual sample sets | per quarter | |
| 500-9,999 | 2 dual sample sets | per year | |
| <500 | 1 TTHM and 1 HAA5 sample: one at the location with the highest TTHM measurement, one at the location with the highest HAA5 measurement3 | per year | |
| 1 All systems shall monitor during the month of highest disinfection byproduct concentrations. | |||
| 2 Systems on quarterly monitoring shall take dual sample sets every 90 days at each monitoring location, except for systems using approved surface water and serving 500-3,300 persons. | |||
| 3 Only one location with a dual sample set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location and month. | |||
(2)
Undisinfected systems that begin using a disinfectant other than UV light after
the applicable dates in 40 Code of Federal Regulations, part 141.600 (71 Fed.
Reg. 388, January 4, 2006), which is incorporated by reference, shall consult
with the State Board to identify compliance monitoring locations for this
subsection. Systems shall then develop a monitoring plan in accordance with
section 64534.8 that includes those
monitoring locations;
(3) Systems
may apply to the State Board to monitor at a reduced frequency in accordance
with table 64534.2-D, any time the LRAA is [LESS THAN EQUAL TO]0.040 mg/L for
TTHM and [LESS THAN EQUAL TO]0.030 mg/L for HAA5 at all monitoring locations.
In addition, the source water annual average TOC level, before any treatment
shall be [LESS THAN EQUAL TO]4.0 mg/L at each treatment plant treating approved
surface water, based on source water TOC monitoring conducted pursuant to
section 64534.6. The application shall
include the results of all TOC, TTHM, and HAA5 monitoring conducted in the
previous 12 months and the proposed revised monitoring plan as required by
section 64534.8. The State Board will
evaluate data submitted with the application to determine whether or not the
system is eligible for the reduced monitoring specified in table 64534.2-D;
Table 64534.2-D Reduced Monitoring Frequency for TTHM and HAA5
| Minimum monitoring frequency | |||
| Source water type | Persons served | Number of distribution system monitoring locations | Monitoring period1 |
| Systems using approved surface water | >=5,000,000 | 10 dual sample sets: at the locations with the five highest TTHM and five highest HAA5 LRAAs | per quarter |
| 1,000,000-4,999,999 | 8 dual sample sets: at the locations with the four highest TTHM and four highest HAA5 LRAAs | per quarter | |
| 250,000-999,999 | 6 dual sample sets: at the locations with the three highest TTHM and three highest HAA5 LRAAs | per quarter | |
| 50,000-249,999 | 4 dual sample sets: at the locations with the two highest TTHM and two highest HAA5 LRAAs | per quarter | |
| 10,000-49,999 | 2 dual sample sets: at the locations with the highest TTHM and highest HAA5 LRAAs | per quarter | |
| 3,301-9,999 | 2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement | per year | |
| 500-3,300 | 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter | per year | |
| Systems using only ground water not under direct influence of surface water | >=500,000 | 4 dual sample sets: at the locations with the two highest TTHM and two highest HAA5 LRAAs | per quarter |
| 100,000-499,999 | 2 dual sample sets: at the locations with the highest TTHM and highest HAA5 LRAAs | per quarter | |
| 10,000-99,999 | 2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement | per year | |
| 500-9,999 | 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter | per year | |
| <500 | 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement, one at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set every third year if the highest TTHM and HAA5 measurements occurred at the same location and quarter | every third year | |
| 1 Systems on quarterly monitoring shall take dual sample sets every 90 days. | |||
(4)
Systems on reduced monitoring shall resume routine monitoring pursuant to table
64534.2-C or conduct increased monitoring pursuant to paragraph (5) (if
applicable), if the TTHM LRAA is >0.040 mg/L or the HAA5 LRAA is >0.030
mg/L at any monitoring location (for systems with quarterly reduced
monitoring); a TTHM sample is >0.060 mg/L or a HAA5 sample is >0.045 mg/L
(for systems with annual or less frequent monitoring); or the source water
annual average TOC level, before any treatment, is >4.0 mg/L at any
treatment plant treating an approved surface water;
(5) Systems that are required to monitor at a
particular location annually or less frequently than annually pursuant to table
64534.2-C or 64534.2-D shall increase monitoring to dual sample sets once per
quarter (taken every 90 days) at all locations if a TTHM sample is >0.080
mg/L or a HAA5 sample is >0.060 mg/L at any location. Systems on increased
monitoring may return to routine monitoring specified in table 64534.2-C if,
after at least four consecutive quarters of monitoring, the LRAA for every
monitoring location is [LESS THAN EQUAL TO]0.060 mg/L for TTHM and [LESS THAN
EQUAL TO]0.045 mg/L for HAA5;
(6)
If the operational evaluation level (OEL) exceeds 0.080 mg/L for TTHM or 0.060
mg/L for HAA5 at any monitoring location, systems shall conduct an operational
evaluation. The operational evaluation shall include the examination of system
treatment and distribution operational practices, including storage tank
operations, excess storage capacity, distribution system flushing, changes in
sources or source water quality, and treatment changes or problems that may
contribute to TTHM and HAA5 formation and what steps could be considered to
minimize future exceedances. Systems that are able to identify the cause of the
OEL exceedance may submit a written request to the State Board to limit the
scope of the evaluation. The request to limit the scope of the evaluation shall
not extend the schedule in section
64537(d) for
submitting the written report to the State Board;
(7) Systems on reduced monitoring pursuant to
table 64534.2-B may remain on reduced monitoring after the applicable date in
table 64530-A for compliance with this subsection provided the system meets
IDSE requirements under section
64530(c) by
qualifying for a 40/30 certification ( 40 CFR part 141.603) or receiving a very
small system waiver ( 40 CFR part 141.604), meets the reduced monitoring
criteria in paragraphs (3) and (4), and does not change or add monitoring
locations from those used for compliance monitoring under subsection (a);
and
(8) Systems on increased
monitoring pursuant to table 64534.2-A shall remain on increased monitoring and
conduct increased monitoring pursuant to paragraph (5) at the locations in the
monitoring plan developed under section
64534.8 beginning at the
applicable date in table 64530-A for compliance with this subsection. Systems
on increased monitoring may return to routine monitoring specified in table
64534.2-C pursuant to paragraph (5).
1. New
section filed 5-18-2006; operative 6-17-2006 (Register 2006, No.
20).
2. Editorial correction of Table 64534.2-B (Register 2007, No.
30).
3. Amendment of subsections (a)(2) and (b)(1)-(3), new
subsection (b)(4), amendment of subsections (c)(1)-(2), new subsections
(c)(3)-(d)(8) and amendment of NOTE filed 5-22-2012; operative 6-21-2012
(Register 2012, No. 21).
4. Amendment of subsections (a)(2). (c)(2)
and (c)(3), repealer of subsections (c)(3)(A)-(B) and amendment of subsection
(d)(2) filed 5-28-2014; operative 7-1-2014 (Register 2014, No.
22).
5. Change without regulatory effect amending subsections
(a)(1), (b)(3), (c)(2)-(3), (d)(2)-(3) and (d)(6) and amending NOTE filed
6-2-2015 pursuant to section
100, title 1, California Code of
Regulations (Register 2015, No. 23).
6. Editorial correction of
Table 64534.2-D within subsection (d)(3) (Register 2021, No.
33).
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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