Community water systems shall conduct monitoring to determine compliance with the maximum contaminant levels specified in § 141.62 in accordance with this section. Non-transient, non-community water systems shall conduct monitoring to determine compliance with the maximum contaminant levels specified in § 141.62 in accordance with this section. Transient, non-community water systems shall conduct monitoring to determine compliance with the nitrate and nitrite maximum contaminant levels in §§ 141.11 and 141.62 (as appropriate) in accordance with this section.
Note: For purposes of this paragraph, surface water systems include systems with a combination of surface and ground sources.
Detection Limits for Inorganic Contaminants
Contaminant | MCL (mg/l) | Methodology | Detection limit (mg/l) |
Antimony | 0.006 | Atomic Absorption; Furnace | 0.003 |
Atomic Absorption; Platform | 0.00085 | ||
ICP-Mass Spectrometry | 0.0004 | ||
Hydride-Atomic Absorption | 0.001 | ||
Arsenic | 0.0106 | Atomic Absorption; Furnace | 0.001 |
Atomic Absorption; Platform-Stabilized Temperature | 0.00057 | ||
Atomic Absorption; Gaseous Hydride | 0.001 | ||
ICP-Mass Spectrometry | 0.00148 | ||
Asbestos | 7 MFL1 | Transmission Electron Microscopy | 0.01 MFL |
Barium | 2 | Atomic Absorption; furnace technique | 0.002 |
Atomic Absorption; direct aspiration | 0.1 | ||
Inductively Coupled Plasma | 0.002 (0.001) | ||
Beryllium | 0.004 | Atomic Absorption; Furnace | 0.0002 |
Atomic Absorption; Platform | 0.000025 | ||
Inductively Coupled Plasma2 | 0.0003 | ||
ICP-Mass Spectrometry | 0.0003 | ||
Cadmium | 0.005 | Atomic Absorption; furnace technique | 0.0001 |
Inductively Coupled Plasma | 0.001 | ||
Chromium | 0.1 | Atomic Absorption; furnace technique | 0.001 |
Inductively Coupled Plasma | 0.007 (0.001) | ||
Cyanide | 0.2 | Distillation, Spectrophotometric3 | 0.02 |
Distillation, Automated, Spectrophotometric3 | 0.005 | ||
Distillation, Amenable, Spectrophotometric4 | 0.02 | ||
Distillation, Selective Electrode3 4 | 0.05 | ||
UV, Distillation, Spectrophotometric9 | 0.0005 | ||
Micro Distillation, Flow Injection, Spectrophotometric3 | 0.0006 | ||
Ligand Exchange with Amperometry4 | 0.0005 | ||
Mercury | 0.002 | Manual Cold Vapor Technique | 0.0002 |
Automated Cold Vapor Technique | 0.0002 | ||
Nickel | xl | Atomic Absorption; Furnace | 0.001 |
Atomic Absorption; Platform | 0.00065 | ||
Inductively Coupled Plasma2 | 0.005 | ||
ICP-Mass Spectrometry | 0.0005 | ||
Nitrate | 10 (as N) | Manual Cadmium Reduction | 0.01 |
Automated Hydrazine Reduction | 0.01 | ||
Automated Cadmium Reduction | 0.05 | ||
Ion Selective Electrode | 1 | ||
Ion Chromatography | 0.01 | ||
Capillary Ion Electrophoresis | 0.076 | ||
Nitrite | 1 (as N) | Spectrophotometric | 0.01 |
Automated Cadmium Reduction | 0.05 | ||
Manual Cadmium Reduction | 0.01 | ||
Ion Chromatography | 0.004 | ||
Capillary Ion Electrophoresis | 0.103 | ||
Selenium | 0.05 | Atomic Absorption; furnace | 0.002 |
Atomic Absorption; gaseous hydride | 0.002 | ||
Thallium | 0.002 | Atomic Absorption; Furnace | 0.001 |
Atomic Absorption; Platform | 0.00075 | ||
ICP-Mass Spectrometry | 0.0003 |
1 MFL = million fibers per liter [GREATER THAN]10 [MICRO]m.
2 Using a 2X preconcentration step as noted in Method 200.7. Lower MDLs may be achieved when using a 4X preconcentration.
3 Screening method for total cyanides.
4 Measures "free" cyanides when distillation, digestion, or ligand exchange is omitted.
5 Lower MDLs are reported using stabilized temperature graphite furnace atomic absorption.
6 The value for arsenic is effective January 23, 2006. Unit then, the MCL is 0.05 mg/L.
7 The MDL reported for EPA method 200.9 (Atomic Absorption; Platform-Stablized Temperature) was determined using a 2x concentration step during sample digestion. The MDL determined for samples analyzed using direct analyses (i.e., no sample digestion) will be higher. Using multiple depositions, EPA 200.9 is capable of obtaining MDL of 0.0001 mg/L.
8 Using selective ion monitoring, EPA Method 200.8 (ICP-MS) is capable of obtaining a MDL of 0.0001 mg/L.
9 Measures total cyanides when UV-digestor is used, and "free" cyanides when UV-digestor is bypassed.
Alternative Testing Methods for Contaminants Listed at 40 CFR 141.23(k)(1)
Contaminant | Methodology | EPA method | SM 21st edition1 | SM 22nd edition28 | SM 23rd edition,49 SM 24th edition66 | SM online3 | ASTM4 | Other |
Alkalinity | Titrimetric | 2320 B | 2320 B | 2320 B | D1067-06 B, 11 B, 16 B | |||
Antimony | Hydride-Atomic Absorption | D 3697-07, -12, -17 | ||||||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Arsenic | Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | D 2972-08 C, -15 C | ||
Hydride Atomic Absorption | 3114 B | 3114 B | 3114 B | 3114 B-09 | D 2972-08 B, -15 B | |||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Barium | Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | ||||
Atomic Absorption; Direct | 3111 D | 3111 D | 3111 D | |||||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Beryllium | Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | ||||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | D 3645-08 B, -15 B | |||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Cadmium | Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | |||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Calcium | EDTA titrimetric | 3500-Ca B | 3500-Ca B | 3500-Ca B | D 511-09, -14 A | |||
Atomic Absorption; Direct Aspiration | 3111 B | 3111 B | 3111 B | D 511-09, -14 B | ||||
Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | |||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Ion Chromatography | D 6919-09, -17 | |||||||
Chromium | Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | ||||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Copper | Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | D 1688-07, -12 C, 17 C | ||
Atomic Absorption; Direct Aspiration | 3111 B | 3111 B | 3111 B | D 1688-07, -12 A, 17 A | ||||
Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | |||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Colorimetry | Hach Method 8026,35 Hach Method 10272.36 | |||||||
Conductivity | Conductance | 2510 B | 2510 B | 2510 B | D 1125-14 A | |||
Cyanide | Manual Distillation with MgCl2 followed by: | 4500-CN-C | 4500-CN-C | 4500-CN-C | 4500-CN-C-99 | D 2036-06 A | ||
Spectrophotometric, Amenable | 4500-CN-G | 4500-CN-G | 4500-CN-G | D 2036-06 B | ||||
Spectrophotometric Manual | 4500-CN-E | 4500-CN-E | 4500-CN-E | D2036-06 A | ||||
Selective Electrode | 4500-CN-F | 4500-CN-F | 4500-CN-F | |||||
Gas Chromatography/Mass Spectrometry Headspace | ME355.01.7 | |||||||
Fluoride | Ion Chromatography | 4110 B | 4110 B | 4110 B | D 4327-11, -17 | |||
Manual Distillation; Colorimetric SPADNS | 4500-F-B, D | 4500-F-B, D | 4500-F-B, D | |||||
Manual Electrode | 4500-F-C | 4500-F-C | 4500-F-C | D 1179-04, 10 B, 16 B | ||||
Automated Alizarin | 4500-F-E | 4500-F-E | 4500-F-E | |||||
Arsenite-Free Colorimetric SPADNS | Hach SPADNS 2 Method 10225,22 Hach Method 10312.67 | |||||||
Lead | Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | D 3559-08 D, 15 D | ||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Differential Pulse Anodic Stripping Voltametry | Method 1001, Rev. 1.1.57 | |||||||
Magnesium | Atomic Absorption | 3111 B | 3111 B | 3111 B | D 511-09, -14 B | |||
Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | |||||
Complexation Titrimetric Methods | 3500-Mg B | 3500-Mg B | 3500-Mg B | D 511-09, -14 A | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Ion Chromatography | D 6919-09, -17 | |||||||
Mercury | Manual, Cold Vapor | 3112 B | 3112 B | 3112 B | 3112 B-09 | D 3223-12, -17 | ||
Nickel | Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | ||||
Atomic Absorption; Direct | 3111 B | 3111 B | 3111 B | |||||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Nitrate | Ion Chromatography | 4110 B | 4110 B | 4110 B | D 4327-11, -17 | |||
Automated Cadmium Reduction | 4500-NO3-F | 4500-NO3-F | 4500-NO3-F | |||||
Manual Cadmium Reduction | 4500-NO3- E | 4500-NO3- E | 4500-NO3- E | |||||
Ion Selective Electrode | 4500-NO3- D | 4500-NO3- D | 4500-NO3- D | |||||
Reduction/Colorimetric | Systea Easy (1-Reagent),8 NECi Nitrate-Reductase.40 | |||||||
Colorimetric; Direct | Hach TNTplusTM 835/836 Method 10206.23 | |||||||
Capillary Ion Electrophoresis | D 6508-15 | |||||||
Nitrite | Ion Chromatography | 4110 B | 4110 B | 4110 B | D 4327-11, -17 | |||
Automated Cadmium Reduction | 4500-NO3-F | 4500-NO3-F | 4500-NO3-F | |||||
Manual Cadmium Reduction | 4500-NO3-E | 4500-NO3-E | 4500-NO3-E | |||||
Spectrophotometric | 4500-NO2-B | 4500-NO2-B | 4500-NO2-B | |||||
Reduction/Colorimetric | Systea Easy (1-Reagent),8 NECi Nitrate-Reductase.40 | |||||||
Capillary Ion Electrophoresis | D 6508-15 | |||||||
Ortho-phosphate | Ion Chromatography | 4110 B | 4110 B | 4110 B | D 4327-11, -17 | |||
Colorimetric, ascorbic acid, single reagent | 4500-P E | 4500-P E | 4500-P E | 4500-P E-99 | ||||
Colorimetric, Automated, Ascorbic Acid | 4500-P F | 4500-P F | 4500-P F | 4500-P F-99 | Thermo Fisher Discrete Analyzer.41 | |||
Capillary Ion Electrophoresis | D 6508-15 | |||||||
pH | Electrometric | 48 150.3 | 4500-H+ B | 4500-H+ B | 4500-H+ B | D 1293-12, -18 | ||
Selenium | Hydride-Atomic Absorption | 3114 B | 3114 B | 3114 B | 3114 B-09 | D 3859-08 A, -15 A | ||
Atomic Absorption; Furnace | 3113 B | 3113 B | 3113 B | 3113 B-04, B-10 | D 3859-08 B, -15 B | |||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Silica | Colorimetric | D859-05, 10, 16 | ||||||
Molybdosilicate | 4500-SiO2 C | 4500-SiO2 C | 4500-SiO2 C | |||||
Heteropoly blue | 4500-SiO2 D | 4500-SiO2 D | 4500-SiO2 D | |||||
Automated for Molybdate-reactive Silica | 4500-SiO2 E | 4500-SiO2 E | 4500-SiO2 E | |||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Inductively Coupled Plasma | 3120 B | 3120 B | 3120 B | |||||
Sodium | Atomic Absorption; Direct Aspiration | 3111 B | 3111 B | 3111 B | ||||
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) | 200.5, Revision 4.22 | |||||||
Ion Chromatography | D 6919-09, -17 | |||||||
Temperature | Thermometric | 2550 | 2550 | 2550 | 2550-10 |
Contaminant | Preservative1 | Container2 | Time3 |
Antimony | HNO3 | P or G | 6 months |
Arsenic | Conc HNO3 to pH [LESS THAN]2 | P or G | 6 months |
Asbestos | 4 °C | P or G | 48 hours4 |
Barium | HNO3 | P or G | 6 months |
Beryllium | HNO3 | P or G | 6 months |
Cadmium | HNO3 | P or G | 6 months |
Chromium | HNO3 | P or G | 6 months |
Cyanide | 4 °C, NaOH | P or G | 14 days |
Fluoride | None | P or G | 1 month |
Mercury | HNO3 | P or G | 28 days |
Nickel | HNO3 | P or G | 6 months |
Nitrate | 4 °C | P or G | 48 hours5 |
Nitrate-Nitrite6 | H2SO4 | P or G | 28 days |
Nitrite | 4 °C | P or G | 48 hours |
Selenium | HNO3 | P or G | 6 months |
Thallium | HNO3 | P or G | 6 months |
1 For cyanide determinations samples must be adjusted with sodium hydroxide to pH 12 at the time off collection. When chilling is indicated the sample must be shipped and stored at 4 °C or less. Acidification of nitrate or metals samples may be with a concentrated acid or a dilute (50% by volume) solution of the applicable concentrated acid. Acidification of samples for metals analysis is encouraged and allowed at the laboratory rather than at the time of sampling provided the shipping time and other instructions in Section 8.3 of EPA Methods 200.7 or 200.8 or 200.9 are followed.
2 P = plastic, hard or soft; G = glass, hard or soft.
3 In all cases samples should be analyzed as soon after collection as possible. Follow additional (if any) information on preservation, containers or holding times that is specified in method.
4 Instructions for containers, preservation procedures and holding times as specified in Method 100.2 must be adhered to for all compliance analyses including those conducted with Method 100.1.
5 If the sample is chlorinated, the holding time for an unacidified sample kept at 4 °C is extended to 14 days.
6 Nitrate-Nitrite refers to a measurement of total nitrate.
Contaminant | Acceptance limit |
Antimony | ±30 at [GREATER THAN EQUAL TO]0.006 mg/1 |
Arsenic | ±30 at [GREATER THAN EQUAL TO]0.003 mg/L |
Asbestos | 2 standard deviations based on study statistics. |
Barium | ±15% at [GREATER THAN EQUAL TO]0.15 mg/1 |
Beryllium | ±15% at [GREATER THAN EQUAL TO]0.001 mg/1 |
Cadmium | ±20% at [GREATER THAN EQUAL TO]0.002 mg/1 |
Chromium | ±15% at [GREATER THAN EQUAL TO]0.01 mg/1 |
Cyanide | ±25% at [GREATER THAN EQUAL TO]0.1 mg/1 |
Fluoride | ±10% at [GREATER THAN EQUAL TO]1 to 10 mg/1 |
Mercury | ±30% at [GREATER THAN EQUAL TO]0.0005 mg/1 |
Nickel | ±15% at [GREATER THAN EQUAL TO]0.01 mg/1 |
Nitrate | ±10% at [GREATER THAN EQUAL TO]0.4 mg/1 |
Nitrite | ±15% at [GREATER THAN EQUAL TO]0.4 mg/1 |
Selenium | ±20% at [GREATER THAN EQUAL TO]0.01 mg/1 |
Thallium | ±30% at [GREATER THAN EQUAL TO]0.002 mg/1 |
40 C.F.R. §141.23
For FEDERAL REGISTER citations affecting § 141.23, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.