Organism | Methodology | Citation1 |
Total Coliform2 | Total Coliform Fermentation Technique3 4 5 | 9221 A, B, C |
Total Coliform Membrane Filter Technique6 | 9222 A, B, C | |
ONPG-MUG Test7 | 9223 | |
Fecal Coliforms2 | Fecal Coliform Procedure8 | 9221 E |
Fecal Coliform Filter Procedure | 9222 D | |
Heterotrophic bacteria2 | Pour Plate Method | 9215 B |
SimPlate11 | ||
Turbidity13 | Nephelometric Method | 2130 B |
Nephelometric Method | 180.19 | |
Great Lakes Instruments | Method 210 | |
Hach FilterTrak | 1013312 |
The procedures shall be done in accordance with the documents listed below. The incorporation by reference of the following documents listed in footnotes 1, 6, 7 and 9-12 was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the documents may be obtained from the sources listed below. Information regarding obtaining these documents can be obtained from the Safe Drinking Water Hotline at 800-426-4791. Documents may be inspected at EPA's Drinking Water Docket, 1301 Constitution Avenue, NW., EPA West, Room B102, Washington DC 20460 (Telephone: 202-566-2426); or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.
1 Except where noted, all methods refer to Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition (1995), or 20th edition (1998), American Public Health Association, 1015 Fifteenth Street, NW., Washington, DC 20005. The cited methods published in any of these three editions may be used. In addition, the following online versions may also be used: 2130 B-01, 9215 B-00, 9221 A, B, C, E-99, 9222 A, B, C, D-97, and 9223 B-97. Standard Methods Online are available at http://www.standardmethods.org. The year in which each method was approved by the Standard Methods Committee is designated by the last two digits in the method number. The methods listed are the only Online versions that may be used.
2 The time from sample collection to initiation of analysis may not exceed 8 hours. Systems must hold samples below 10 deg. C during transit.
3 Lactose broth, as commercially available, may be used in lieu of lauryl tryptose broth, if the system conducts at least 25 parallel tests between this medium and lauryl tryptose broth using the water normally tested, and this comparison demonstrates that the false-positive rate and false-negative rate for total coliform, using lactose broth, is less than 10 percent.
4 Media should cover inverted tubes at least one-half to two-thirds after the sample is added.
5 No requirement exists to run the completed phase on 10 percent of all total coliform-positive confirmed tubes.
6 MI agar also may be used. Preparation and use of MI agar is set forth in the article, "New medium for the simultaneous detection of total coliform and Escherichia coli in water" by Brenner, K.P., et. al., 1993, Appl. Environ. Microbiol. 59:3534-3544. Also available from the Office of Water Resource Center (RC-4100T), 1200 Pennsylvania Avenue, NW., Washington DC 20460, EPA/600/J-99/225. Verification of colonies is not required.
7 The ONPG-MUG Test is also known as the Autoanalysis Colilert System.
8 A-1 broth may be held up to 7 days in a tightly closed screw cap tube at 4 °C.
9 "Methods for the Determination of Inorganic Substances in Environmental Samples", EPA/600/R-93/100, August 1993. Available at NTIS, PB94-121811.
10 GLI Method 2, "Turbidity," November 2, 1992, Great Lakes Instruments, Inc., 8855 North 55th Street, Milwaukee, WI 53223.
11 A description of the SimPlate method, "IDEXX SimPlate TM HPC Test Method for Heterotrophs in Water," November 2000, can be obtained from IDEXX Laboratories, Inc., 1 IDEXX Drive, Westbrook, ME 04092, telephone (800) 321-0207.
12 A description of the Hach FilterTrak Method 10133, "Determination of Turbidity by Laser Nephelometry," January 2000, Revision 2.0, can be obtained from; Hach Co., P.O. Box 389, Loveland, CO 80539-0389, telephone: 800-227-4224.
13 Styrene divinyl benzene beads (e.g., AMCO-AEPA-1 or equivalent) and stabilized formazin (e.g., Hach StablCalTM or equivalent) are acceptable substitutes for formazin.
Residual | Methodology | SM1 | SM Online2 | Other |
Free Chlorine | Amperometric Titration | 4500-Cl D | 4500-Cl D-00 | D1253-033 |
DPD Ferrous Titrimetric | 4500-Cl F | 4500-Cl F-00 | ||
DPD Colorimetric | 4500-Cl G | 4500-Cl G-00 | ||
Syringaldazine (FACTS) | 4500-Cl H | 4500-Cl H-00 | ||
Total Chlorine | Amperometric Titration | 4500-Cl D | 4500-Cl D-00 | D1253-033 |
Amperometric Titration (low level measurement) | 4500-Cl E | 4500-Cl E-00 | ||
DPD Ferrous Titrimetric | 4500-Cl F | 4500-Cl F-00 | ||
DPD Colorimetric | 4500-Cl G | 4500-Cl G-00 | ||
Iodometric Electrode | 4500-Cl I | 4500-Cl I-00 | ||
Chlorine Dioxide | Amperometric Titration | 4500-ClO2 C | 4500-ClO2 C-00 | |
DPD Method | 4500-ClO2 D | |||
Amperometric Titration | 4500-ClO2 E | 4500-ClO2 E-00 | ||
Spectrophotometric | 327.0, Revision 1.14 | |||
Ozone | Indigo Method | 4500-O3 B | 4500-O3 B-97 |
1 All the listed methods are contained in the 18th, 19th, and 20th editions of Standard Methods for the Examination of Water and Wastewater, 1992, 1995, and 1998; the cited methods published in any of these three editions may be used.
2 Standard Methods Online are available at http://www.standardmethods.org. The year in which each method was approved by the Standard Methods Committee is designated by the last two digits in the method number. The methods listed are the only Online versions that may be used.
3Annual Book of ASTM Standards, Vol. 11.01, 2004 ; ASTM International; any year containing the cited version of the method may be used. Copies of this method may be obtained from ASTM International, 100 Barr Harbor Drive, P.O. Box C700 West Conshohocken, PA 19428-2959.
4 EPA Method 327.0, Revision 1.1, "Determination of Chlorine Dioxide and Chlorite Ion in Drinking Water Using Lissamine Green B and Horseradish Peroxidase with Detection by Visible Spectrophotometry," USEPA, May 2005, EPA 815-R-05-008. Available online at http://www.epa.gov/safewater/methods/sourcalt.html.
System size (persons served) | Samples/week1 |
[LESS THAN EQUAL TO]500 | 1 |
501 to 3,300 | 2 |
3,301 to 10,000 | 3 |
10,001 to 25,000 | 4 |
[GREATER THAN]25,000 | 5 |
1 Must be taken on separate days.
Also, one fecal or total coliform density measurement must be made every day the system serves water to the public and the turbidity of the source water exceeds 1 NTU (these samples count towards the weekly coliform sampling requirement) unless the State determines that the system, for logistical reasons outside the system's control, cannot have the sample analyzed within 30 hours of collection.
Table 1.1-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 0.5 °C or Lower1
Residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 137 | 163 | 195 | 237 | 277 | 329 | 390 |
0.6 | 141 | 168 | 200 | 239 | 286 | 342 | 407 |
0.8 | 145 | 172 | 205 | 246 | 295 | 354 | 422 |
1.0 | 148 | 176 | 210 | 253 | 304 | 365 | 437 |
1.2 | 152 | 180 | 215 | 259 | 313 | 376 | 451 |
1.4 | 155 | 184 | 221 | 266 | 321 | 387 | 464 |
1.6 | 157 | 189 | 226 | 273 | 329 | 397 | 477 |
1.8 | 162 | 193 | 231 | 279 | 338 | 407 | 489 |
2.0 | 165 | 197 | 236 | 286 | 346 | 417 | 500 |
2.2 | 169 | 201 | 242 | 297 | 353 | 426 | 511 |
2.4 | 172 | 205 | 247 | 298 | 361 | 435 | 522 |
2.6 | 175 | 209 | 252 | 304 | 368 | 444 | 533 |
2.8 | 178 | 213 | 257 | 310 | 375 | 452 | 543 |
3.0 | 181 | 217 | 261 | 316 | 382 | 460 | 552 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature and at the higher pH.
Table 1.2-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 5.0 °C1
Free residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 97 | 117 | 139 | 166 | 198 | 236 | 279 |
0.6 | 100 | 120 | 143 | 171 | 204 | 244 | 291 |
0.8 | 103 | 122 | 146 | 175 | 210 | 252 | 301 |
1.0 | 105 | 125 | 149 | 179 | 216 | 260 | 312 |
1.2 | 107 | 127 | 152 | 183 | 221 | 267 | 320 |
1.4 | 109 | 130 | 155 | 187 | 227 | 274 | 329 |
1.6 | 111 | 132 | 158 | 192 | 232 | 281 | 337 |
1.8 | 114 | 135 | 162 | 196 | 238 | 287 | 345 |
2.0 | 116 | 138 | 165 | 200 | 243 | 294 | 353 |
2.2 | 118 | 140 | 169 | 204 | 248 | 300 | 361 |
2.4 | 120 | 143 | 172 | 209 | 253 | 306 | 368 |
2.6 | 122 | 146 | 175 | 213 | 258 | 312 | 375 |
2.8 | 124 | 148 | 178 | 217 | 263 | 318 | 382 |
3.0 | 126 | 151 | 182 | 221 | 268 | 324 | 389 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.
Table 1.3-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 10.0 °C1
Free residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 73 | 88 | 104 | 125 | 149 | 177 | 209 |
0.6 | 75 | 90 | 107 | 128 | 153 | 183 | 218 |
0.8 | 78 | 92 | 110 | 131 | 158 | 189 | 226 |
1.0 | 79 | 94 | 112 | 134 | 162 | 195 | 234 |
1.2 | 80 | 95 | 114 | 137 | 166 | 200 | 240 |
1.4 | 82 | 98 | 116 | 140 | 170 | 206 | 247 |
1.6 | 83 | 99 | 119 | 144 | 174 | 211 | 253 |
1.8 | 86 | 101 | 122 | 147 | 179 | 215 | 259 |
2.0 | 87 | 104 | 124 | 150 | 182 | 221 | 265 |
2.2 | 89 | 105 | 127 | 153 | 186 | 225 | 271 |
2.4 | 90 | 107 | 129 | 157 | 190 | 230 | 276 |
2.6 | 92 | 110 | 131 | 160 | 194 | 234 | 281 |
2.8 | 93 | 111 | 134 | 163 | 197 | 239 | 287 |
3.0 | 95 | 113 | 137 | 166 | 201 | 243 | 292 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.
Table 1.4-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 15.0 °C1
Free residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 49 | 59 | 70 | 83 | 99 | 118 | 140 |
0.6 | 50 | 60 | 72 | 86 | 102 | 122 | 146 |
0.8 | 52 | 61 | 73 | 88 | 105 | 126 | 151 |
1.0 | 53 | 63 | 75 | 90 | 108 | 130 | 156 |
1.2 | 54 | 64 | 76 | 92 | 111 | 134 | 160 |
1.4 | 55 | 65 | 78 | 94 | 114 | 137 | 165 |
1.6 | 56 | 66 | 79 | 96 | 116 | 141 | 169 |
1.8 | 57 | 68 | 81 | 98 | 119 | 144 | 173 |
2.0 | 58 | 69 | 83 | 100 | 122 | 147 | 177 |
2.2 | 59 | 70 | 85 | 102 | 124 | 150 | 181 |
2.4 | 60 | 72 | 86 | 105 | 127 | 153 | 184 |
2.6 | 61 | 73 | 88 | 107 | 129 | 156 | 188 |
2.8 | 62 | 74 | 89 | 109 | 132 | 159 | 191 |
3.0 | 63 | 76 | 91 | 111 | 134 | 162 | 195 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.
Table 1.5-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 20 °C1
Free residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 36 | 44 | 52 | 62 | 74 | 89 | 105 |
0.6 | 38 | 45 | 54 | 64 | 77 | 92 | 109 |
0.8 | 39 | 46 | 55 | 66 | 79 | 95 | 113 |
1.0 | 39 | 47 | 56 | 67 | 81 | 98 | 117 |
1.2 | 40 | 48 | 57 | 69 | 83 | 100 | 120 |
1.4 | 41 | 49 | 58 | 70 | 85 | 103 | 123 |
1.6 | 42 | 50 | 59 | 72 | 87 | 105 | 126 |
1.8 | 43 | 51 | 61 | 74 | 89 | 108 | 129 |
2.0 | 44 | 52 | 62 | 75 | 91 | 110 | 132 |
2.2 | 44 | 53 | 63 | 77 | 93 | 113 | 135 |
2.4 | 45 | 54 | 65 | 78 | 95 | 115 | 138 |
2.6 | 46 | 55 | 66 | 80 | 97 | 117 | 141 |
2.8 | 47 | 56 | 67 | 81 | 99 | 119 | 143 |
3.0 | 47 | 57 | 68 | 83 | 101 | 122 | 146 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.
Table 1.6-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 25 °C1 and Higher
Free residual (mg/l) | pH | ||||||
[LESS THAN EQUAL TO]6.0 | 6.5 | 7.0 | 7.5 | 8.0 | 8.5 | [LESS THAN EQUAL TO]9.0 | |
[LESS THAN EQUAL TO]0.4 | 24 | 29 | 35 | 42 | 50 | 59 | 70 |
0.6 | 25 | 30 | 36 | 43 | 51 | 61 | 73 |
0.8 | 26 | 31 | 37 | 44 | 53 | 63 | 75 |
1.0 | 26 | 31 | 37 | 45 | 54 | 65 | 78 |
1.2 | 27 | 32 | 38 | 46 | 55 | 67 | 80 |
1.4 | 27 | 33 | 39 | 47 | 57 | 69 | 82 |
1.6 | 28 | 33 | 40 | 48 | 58 | 70 | 84 |
1.8 | 29 | 34 | 41 | 49 | 60 | 72 | 86 |
2.0 | 29 | 35 | 41 | 50 | 61 | 74 | 88 |
2.2 | 30 | 35 | 42 | 51 | 62 | 75 | 90 |
2.4 | 30 | 36 | 43 | 52 | 63 | 77 | 92 |
2.6 | 31 | 37 | 44 | 53 | 65 | 78 | 94 |
2.8 | 31 | 37 | 45 | 54 | 66 | 80 | 96 |
3.0 | 32 | 38 | 46 | 55 | 67 | 81 | 97 |
1 These CT values achieve greater than a 99.99 percent inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.
Table 2.1-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Chlorine Dioxide and Ozone1
Temperature | ||||||
[LESS THAN]1 °C | 5 °C | 10 °C | 15 °C | 20 °C | [GREATER THAN EQUAL TO]25 °C | |
Chlorine dioxide | 63 | 26 | 23 | 19 | 15 | 11 |
Ozone | 2.9 | 1.9 | 1.4 | 0.95 | 0.72 | 0.48 |
1 These CT values achieve greater than 99.99 percent inactivation of viruses. CT values between the indicated temperatures may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature for determining CT99.9 values between indicated temperatures.
Table 3.1-CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts By Chloramines1
Temperature | |||||
[LESS THAN]1 °C | 5 °C | 10 °C | 15 °C | 20 °C | 25 °C |
3,800 | 2,200 | 1,850 | 1,500 | 1,100 | 750 |
1 These values are for pH values of 6 to 9. These CT values may be assumed to achieve greater than 99.99 percent inactivation of viruses only if chlorine is added and mixed in the water prior to the addition of ammonia. If this condition is not met, the system must demonstrate, based on on-site studies or other information, as approved by the State, that the system is achieving at least 99.99 percent inactivation of viruses. CT values between the indicated temperatures may be determined by linear interpolation. If no interpolation is used, use the CT99.9 value at the lower temperature for determining CT99.9 values between indicated temperatures.
lamblia inactivation requirement has been achieved.
must be calculated using the method in paragraph (b)(4)(i)(B) of this section to determine if the system is in compliance with § 141.72(a) .
System size by population | Samples/day1 |
[LESS THAN]500 | 1 |
501 to 1,000 | 2 |
1,001 to 2,500 | 3 |
2,501 to 3,300 | 4 |
1 The day's samples cannot be taken at the same time. The sampling intervals are subject to State review and approval.
If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the system must take a grab sample every 4 hours until the residual concentration is equal to or greater than 0.2 mg/l.
System size by population | Samples/day1 |
±500 | 1 |
501 to 1,000 | 2 |
1,001 to 2,500 | 3 |
2,501 to 3,300 | 4 |
1 The day's samples cannot be taken at the same time. The sampling intervals are subject to State review and approval.
If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the system must take a grab sample every 4 hours until the residual disinfectant concentration is equal to or greater than 0.2 mg/l.
40 C.F.R. §141.74