Wastewater sampling and test procedures study guide
40 CFR Part 136 sets the test procedures that, except as noted in sections 136.4, 136.5 and 136.6, must be used when the specified waste constituents are required to be measured for NPDES applications and reports, State section 401 certifications, and sewage sludge permits and Part 503 records. This guide sets out what sections 136.1, 136.2 and 136.3 state on applicability and definitions, approved and alternate test procedures, Table II (required containers, preservation techniques and holding times) and its footnotes on grab and composite samples, when holding time begins, and requests for limited use changes. Many rules carry "except", "unless specified otherwise" or "under certain circumstances" conditions. Your State program and your facility's permit may have their own requirements, so check them too. Every point links to the regulation and quotes its exact words.
Applicability and definitions
The Part 136 procedures must be used, except as noted in 136.4, 136.5 and 136.6, whenever the listed waste constituent is required to be measured for the purposes in 136.1(a).
“The procedures prescribed herein shall, except as noted in §§ 136.4, 136.5, and 136.6, be used to perform the measurements indicated whenever the waste constituent specified is required to be measured for:”
Those purposes include applications submitted to the Director and reports required under NPDES permits, and other requests for effluent data under parts 122 through 125.
“An application submitted to the Director and/or reports required to be submitted under NPDES permits or other requests for quantitative or qualitative effluent data under parts 122 through 125 of this chapter; and”
They also include certifications issued by States under section 401 of the Clean Water Act.
“Certifications issued by States pursuant to section 401 of the Clean Water Act (CWA), as amended.”
For sewage sludge, the procedures in Part 136 and in Part 503 must be used for measurements for a sewage sludge permit application under section 405(f) of the Clean Water Act and for Part 503 recordkeeping and reporting.
“The procedure prescribed herein and in part 503 of title 40 shall be used to perform the measurements required for an application submitted to the Administrator or to a State for a sewage sludge permit under section 405(f) of the Clean Water Act and for recordkeeping and reporting requirements under part 503 of title 40.”
For the NPDES program, when more than one test procedure is approved for a pollutant, the procedure used must be sufficiently sensitive as defined in the Part 122 sections cited.
“For the purposes of the NPDES program, when more than one test procedure is approved under this part for the analysis of a pollutant or pollutant parameter, the test procedure must be sufficiently sensitive as defined at 40 CFR 122.21(e)(3) and 122.44(i)(1)(iv).”
In Part 136, "Director" has the meaning given in 40 CFR 122.2.
“Director means the director as defined in 40 CFR 122.2.”
NPDES is the national system for issuing permits under section 402 of the Act, and it includes any State or interstate program approved by the Administrator in whole or in part.
“National Pollutant Discharge Elimination System (NPDES) means the national system for the issuance of permits under section 402 of the Act and includes any State or interstate program which has been approved by the Administrator, in whole or in part, pursuant to section 402 of the Act.”
Detection limit is the minimum concentration of an analyte that can be measured and reported with 99% confidence that it is distinguishable from the method blank results, as determined by the procedure in appendix B to Part 136.
“Detection limit means the minimum concentration of an analyte (substance) that can be measured and reported with a 99% confidence that the analyte concentration is distinguishable from the method blank results as determined by the procedure set forth at appendix B of this part.”
Approved test procedures and alternatives
Parameters with approved methods are listed, with test procedure descriptions and references, in Tables IA through IH of 136.3.
“Parameters or pollutants, for which methods are approved, are listed together with test procedure descriptions and references in Tables IA, IB, IC, ID, IE, IF, IG, and IH of this section.”
The full texts of Methods 601-613, 624.1, 625.1, 1613, 1624 and 1625 are printed in appendix A to Part 136, and Method 200.7 is printed in appendix C.
“The full texts of Methods 601-613, 624.1, 625.1, 1613, 1624, and 1625 are printed in appendix A of this part, and the full text of Method 200.7 is printed in appendix C of this part.”
The procedure for determining the method detection limit is given in appendix B to Part 136.
“The full text for determining the method detection limit when using the test procedures is given in appendix B of this part.”
If the reporting requirements of 40 CFR parts 122 and 125 conflict with reporting requirements tied to a listed method, parts 122 and 125 control and determine the permittee's reporting requirements.
“In the event of a conflict between the reporting requirements of 40 CFR parts 122 and 125 and any reporting requirements associated with the methods listed in these tables, the provisions of 40 CFR parts 122 and 125 are controlling and will determine a permittee's reporting requirements.”
Discharge parameter values for which reports are required must be determined by one of the standard analytical test procedures described in Tables IA to IH, or by an alternate test procedure as set out in the next point (one of the options).
“The discharge parameter values for which reports are required must be determined by one of the standard analytical test procedures incorporated by reference and described in Tables IA, IB, IC, ID, IE, IF, IG, and IH or by any alternate test”
That alternate test procedure is one that has been approved by the Administrator under 136.3(d) and 136.4 and 136.5. Under certain circumstances (136.3(c), 136.5(a) through (d), or 40 CFR 401.13), other additional or alternate test procedures may be used.
“procedure which has been approved by the Administrator under the provisions of paragraph (d) of this section and §§ 136.4 and 136.5. Under certain circumstances (paragraph (c) of this section, § 136.5(a) through (d) or 40 CFR 401.13,) other additional or alternate test procedures may be used.”
Under certain circumstances, the Director may set discharge limits for a parameter that has no test procedure in Part 136 or in parts 405 through 499; the Director then specifies the test procedure.
“Under certain circumstances, the Director may establish limitations on the discharge of a parameter for which there is no test procedure in this part or in 40 CFR parts 405 through 499. In these instances the test procedure shall be specified by the Director.”
Under certain circumstances, the Administrator may approve additional alternate test procedures for nationwide use, on the recommendation of the Alternate Test Procedure Program Coordinator in Washington, DC.
“Under certain circumstances, the Administrator may approve additional alternate test procedures for nationwide use, upon recommendation by the Alternate Test Procedure Program Coordinator, Washington, DC.”
Not covered here
The method tables IA to IH, their notes, and the material incorporated by reference in 136.3(b) are not set out here. Sections 136.4, 136.5 and 136.6 are outside this set. Your State program and your facility's permit may have their own requirements, so check them too. We only write what an official source states, so study these parts with your certifying program's materials.
Table II and limited use changes
Sample preservation procedures, container materials and maximum allowable holding times for the parameters in Tables IA to IH are prescribed in Table II.
“Sample preservation procedures, container materials, and maximum allowable holding times for parameters are cited in Tables IA, IB, IC, ID, IE, IF, IG, and IH are prescribed in Table II.”
Information in Table II takes precedence over information in specific methods or elsewhere.
“Information in the table takes precedence over information in specific methods or elsewhere.”
Any person may apply for a change from the prescribed preservation techniques, container materials and maximum holding times for samples taken from a specific discharge.
“Any person may apply for a change from the prescribed preservation techniques, container materials, and maximum holding times applicable to samples taken from a specific discharge.”
Applications for these limited use changes may be made by letter to the Regional ATP Program Coordinator or the permitting authority in the Region where the discharge will occur.
“Applications for such limited use changes may be made by letters to the Regional Alternative Test Procedure (ATP) Program Coordinator or the permitting authority in the Region in which the discharge will occur.”
The application should include enough data to show that the changes do not adversely affect the integrity of the sample.
“Sufficient data should be provided to assure such changes in sample preservation, containers or holding times do not adversely affect the integrity of the sample.”
The Regional ATP Coordinator or permitting authority reviews the application and notifies the applicant and the appropriate State agency of approval or rejection.
“The Regional ATP Coordinator or permitting authority will review the application and then notify the applicant and the appropriate State agency of approval or rejection of the use of the alternate test procedure.”
The decision on the request will be made within 90 days of receipt of the application by the Regional Administrator.
“requirements will be made within 90 days of receipt of the application by the Regional Administrator.”
An analyst may not modify the sample preservation or holding time requirements of an approved method unless the requirements of 136.3 are met.
“An analyst may not modify any sample preservation and/or holding time requirements of an approved method unless the requirements of this section are met.”
Not covered here
Table II itself is not reproduced; check the row for each parameter in the regulation. We only write what an official source states, so study these parts with your certifying program's materials.
Containers and preservation
In Table II, "P" means polyethylene and "FP" means fluoropolymer (PTFE or other fluoropolymer), unless Table II says otherwise.
“"P" is for polyethylene; "FP" is fluoropolymer (polytetrafluoroethylene [PTFE]; Teflon®), or other fluoropolymer, unless stated otherwise in this Table II”
"G" means glass, "PA" means any sterilizable (autoclavable) plastic, and "LDPE" means low density polyethylene.
“"G" is glass; "PA" is any plastic that is made of a sterilizable material (polypropylene or other autoclavable plastic); "LDPE" is low density polyethylene.”
Except where Table II and the method say otherwise, each grab sample must be preserved within 15 minutes of collection.
“Except where noted in this Table II and the method for the parameter, preserve each grab sample within 15 minutes of collection.”
A composite sample collected with an automated sampler must be refrigerated at ≤6 °C during collection, unless Table II or the method specifies otherwise.
“For a composite sample collected with an automated sample (e.g., using a 24-hour composite sample; see 40 CFR 122.21(g)(7)(i) or 40 CFR part 403, appendix E), refrigerate the sample at ≤6 °C during collection unless specified otherwise in this Table II or in the method(s).”
A composite sample to be split into aliquots must be kept at ≤6 °C, unless Table II or the method specifies otherwise, until collection, splitting and preservation are completed.
“For a composite sample to be split into separate aliquots for preservation and/or analysis, maintain the sample at ≤6 °C, unless specified otherwise in this Table II or in the method(s), until collection, splitting, and preservation is completed.”
The preservative is added to the container before collection when it will not compromise the integrity of a grab sample, a composite sample or an aliquot split from a composite sample within 15 minutes of collection.
“Add the preservative to the sample container prior to sample collection when the preservative will not compromise the integrity of a grab sample, a composite sample, or aliquot split from a composite sample within 15 minutes of collection.”
If a composite measurement is required but a composite sample would compromise sample integrity, individual grab samples must be collected at prescribed time intervals, analyzed separately and the concentrations averaged.
“If a composite measurement is required but a composite sample would compromise sample integrity, individual grab samples must be collected at prescribed time intervals (e.g., 4 samples over the course of a day, at 6-hour intervals). Grab samples must be analyzed separately and the concentrations averaged.”
Alternatively, grab samples may be collected in the field and composited in the laboratory if the compositing procedure produces results equivalent to arithmetic averaging of the individual grab sample results.
“Alternatively, grab samples may be collected in the field and composited in the laboratory if the compositing procedure produces results equivalent to results produced by arithmetic averaging of results of analysis of individual grab samples.”
A sample shipped by common carrier or sent by the U.S. Postal Service must comply with the DOT Hazardous Materials Regulations; the person offering it for transportation is responsible for compliance.
“When any sample is to be shipped by common carrier or sent via the U.S. Postal Service, it must comply with the Department of Transportation Hazardous Materials Regulations (49 CFR part 172). The person offering such material for transportation is responsible for ensuring such compliance.”
Footnote 18 to Table II states that aqueous samples must be preserved at ≤6 °C and should not be frozen unless data showing freezing does not adversely impact sample integrity is maintained on file and accepted as valid by the regulatory authority.
“Aqueous samples must be preserved at ≤6 °C, and should not be frozen unless data demonstrating that sample freezing does not adversely impact sample integrity is maintained on file and accepted as valid by the regulatory authority.”
Under footnote 18, the preservation temperature does not apply to samples analyzed immediately (less than 15 minutes).
“The preservation temperature does not apply to samples that are analyzed immediately (less than 15 minutes).”
The Table II row "47. Winkler" (listed after the dissolved oxygen probe row) gives a glass bottle and top as the container and "Fix on site and store in dark" as the preservation.
“47. Winkler G, Bottle and top Fix on site and store in dark”
Holding times
Samples should be analyzed as soon as possible after collection; the Table II times are the maximum times a sample may be held before the start of analysis and still be valid.
“Samples should be analyzed as soon as possible after collection. The times listed are the maximum times that samples may be held before the start of analysis and still be considered valid.”
Samples may be held longer only if the permittee or monitoring laboratory has data on file showing the analytes are stable for the longer time for those sample types, and has received a variance from the Regional ATP Coordinator under 136.3(e).
“Samples may be held for longer periods only if the permittee or monitoring laboratory have data on file to show that, for the specific types of samples under study, the analytes are stable for the longer time, and has received a variance from the Regional ATP Coordinator under § 136.3(e).”
For a grab sample, the holding time begins at the time of collection.
“For a grab sample, the holding time begins at the time of collection.”
For a composite sample collected with an automated sampler, the holding time begins at the end of collection of the composite sample.
“For a composite sample collected with an automated sampler (e.g., using a 24-hour composite sampler; see 40 CFR 122.21(g)(7)(i) or 40 CFR part 403, appendix E), the holding time begins at the time of the end of collection of the composite sample.”
For a set of grab samples composited in the field or laboratory, the holding time begins when the last grab sample in the set is collected.
“For a set of grab samples composited in the field or laboratory, the holding time begins at the time of collection of the last grab sample in the set.”
Some samples may not be stable for the maximum time; a permittee or monitoring laboratory must hold a sample for a shorter time if it knows a shorter time is needed for stability.
“Some samples may not be stable for the maximum time period given in the table. A permittee or monitoring laboratory is obligated to hold the sample for a shorter time if it knows that a shorter time is necessary to maintain sample stability.”
For a set of grab samples to be composited that is collected across two calendar dates, the date of collection is both dates (for example, November 14-15).
“For a set of grab samples to be composited, and that are collected across two calendar dates, the date of collection is the dates of the two days; e.g., November 14-15.”
Table II lists total residual chlorine in P or G containers, no preservation required, analyzed within 15 minutes.
“17. Chlorine, total residual P, G None required Analyze within 15 minutes.”
Not covered here
Holding times for each parameter are in the Table II rows; only examples are given here. We only write what an official source states, so study these parts with your certifying program's materials.
Footnotes for specific tests
For the bacterial tests marked with footnote 22, analysis should begin as soon as possible after receipt, and incubation must be started no later than 8 hours from the time of collection.
“Sample analysis should begin as soon as possible after receipt; sample incubation must be started no later than 8 hours from time of collection.”
For fecal coliform samples of sewage sludge (biosolids) only, the holding time is extended to 24 hours for Class A composted, Class B aerobically digested and Class B anaerobically digested samples, using EPA Method 1680 or 1681.
“For fecal coliform samples for sewage sludge (biosolids) only, the holding time is extended to 24 hours for the following sample types using either EPA Method 1680 (LTB-EC) or 1681 (A-1): Class A composted, Class B aerobically digested, and Class B anaerobically digested.”
For the protozoan tests, holding time runs from collection to elution for samples shipped in bulk, and from filtration to elution for samples filtered in the field.
“Holding time is calculated from time of sample collection to elution for samples shipped to the laboratory in bulk and calculated from the time of sample filtration to elution for samples filtered in the field.”
For dissolved metals, grab samples are filtered within 15 minutes of collection and before preservatives are added.
“For dissolved metals, filter grab samples within 15 minutes of collection and before adding preservatives.”
Under footnote 19, an aqueous sample may be collected and shipped without acid preservation.
“An aqueous sample may be collected and shipped without acid preservation.”
The acid is then added at least 24 hours before analysis to dissolve any metals that adsorb to the container walls; if the sample must be analyzed within 24 hours of collection, the acid is added immediately.
“added at least 24 hours before analysis to dissolve any metals that adsorb to the container walls. If the sample must be analyzed within 24 hours of collection, add the acid immediately (see footnote 2).”
A sample collected for total or dissolved trace level mercury must be analyzed within 90 days of collection.
“A sample that has been collected for determination of total or dissolved trace level mercury must be analyzed within 90 days of sample collection.”
For toxicity samples, enough ice must be shipped so ice is still present on arrival, and the sample temperature must still be measured immediately on arrival.
“Place sufficient ice with the samples in the shipping container to ensure that ice is still present when the samples arrive at the laboratory. However, even if ice is present when the samples arrive, immediately measure the temperature of the samples and confirm that the preservation temperature maximum has not been exceeded.”
Aqueous toxicity samples must not be frozen; hand-delivered samples used on the day of collection do not need to be cooled to 0 to 6 °C before the test starts.
“Aqueous samples must not be frozen. Hand-delivered samples used on the day of collection do not need to be cooled to 0 to 6 °C prior to test initiation.”
Orthophosphate samples are filtered immediately upon collection (within 15 minutes) to assess the dissolved or bio-available form.
“The immediate filtration requirement in orthophosphate measurement is to assess the dissolved or bio-available form of orthophosphorus (i.e., that which passes through a 0.45-micron filter), hence the requirement to filter the sample immediately upon collection (i.e., within 15 minutes of collection).”
Not covered here
The footnotes for organic compounds (8 to 15), oxidants and cyanide (5 and 6) and hexavalent chromium (20) are not covered point by point. We only write what an official source states, so study these parts with your certifying program's materials.
Sources
- eCFR: 40 CFR 136.1, Applicability (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 136.2, Definitions (as of Nov 4, 2026)Checked November 6, 2026
- eCFR: 40 CFR 136.3, Identification of test procedures (as of Nov 4, 2026)Checked November 6, 2026
Other Wastewater operator study guides: Secondary treatment standards, NPDES permit conditions, Permit limits and monitoring, Industrial pretreatment, Biosolids use and disposal, Pathogen and vector attraction reduction