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Summary of Updates Since the 24th Edition

Since the 24th edition of Standard Methods for the Examination of Water and Wastewater published in January of 2023, multiple sections have been updated and approved by the Standard Methods Committee. The summary of changes for each section is listed below. Please note that these summaries are not an exhaustive list of changes. Laboratory analysts should review the methods that have been updated for relevant information.

2110 Appearance 

Posted online: April 18, 2025

SM 2110 has undergone a substantial rewrite and now consists of two subsections, A and B. SM 2110 A discusses all aspects of water quality aesthetics, including appearance, odor, and taste. In addition, this subsection now includes drinking water regulations and guidance levels for drinking water aesthetics published by the US EPA, the WHO, the EU, Canada, and India. SM 2110 B Tools for Assessing the Aesthetic Quality of Water is a new section and contains a color Guide to Particles and Color in Tap Water, an example check-if-apply list for customer complaints, and a new table to guide​ selecting the appropriate sensory method from Part 2000 to meet the objectives of the method's application. Go to Section 2110.

2150 Taste and Odor

Posted online: April 17, 2025

SM 2150 A was editorially revised for clarity and conciseness and to update references. SM 2150 B was technically revised to clarify sample and storage information (B.1d), the temperature range at which to perform the test (B.1f), and the use of a method blank for the QC of odor methods (B.1g). Also, the temperature range required for a water bath was altered (B.2b) and the use of plastic stoppers prohibited (B.2c). SM 2150 C Total Intensity of Odor was technically revised to include data from an interlaboratory study using TIO as a function of true geosmin concentration. Substantial changes appear in the temperature-range specifications (C.1e), some clarifications in sample storage and handling (C.1c), and changes to guidance for panelist orientation (C.5). References in both B and C were updated. SM 2150 D Attribute Rating Test for Odor Compounds in Water is a new method, added as a sensory analysis using a single reference standard to determine the relative concentration of geosmin and 2-methylisoborneol in process control samples. Interlaboratory study data included ART ratings as a function of true T&O concentration with a high degree of reproducibility.

4500-PAA PFA Peracetic Acid and Performic Acid (Residual)

Posted online: January 3, 2025. See video abstract.

The entire section was substantially updated to add the determination of PFA residuals to the method information and procedures. Further, the below-equation information in B.4b.9 (calculation of PAA concentration) was corrected to show milliequivalents of PAA rather than milliequivalents of H2O2.

6020 Quality Assurance/Quality Control

Posted online: April 18, 2025.

SM 6020 A was editorially revised. SM 6020 B Laboratory QC Practices and SM 6020 C Additional QC Practices were technically revised to update quality control practices applicable to all methods in Part 6000, unless otherwise noted in individual methods. Moving forward, Part 6000 methods will be edited to reference SM 6020 for required QC instead of repeating the same requirements in each individual method. Updated Method Detection Limit procedures and calculations were also added. 

6040 Taste and Odor Compounds

Posted online: April 18, 2025

SM 6040 A, B, C, and E were editorially revised. SM 6040 D T&O Compounds by Solid-Phase Microextraction GC–MS was completely revised and now includes 19 T&O compounds with descriptors such as earthy, musty, grassy, woody, fishy, septic, fruity, and sweet. An interlaboratory comparison assessed method accuracy, precision, reproducibility, and ruggedness. Three laboratories met QC acceptance for all 19 compounds. Other major updates include reduced sample volume, optimized instrument method settings, ruggedness evaluation, and holding times for analytes in DI, tap, and raw water.

7020 Quality System 

Posted online: April 21, 2025

Table 7020:1 has been updated to reflect new consensus acceptance limits for Safe Drinking Water Act (SDWA) proficiency test (PT) compliance sample (PT) results for radiochemical analyses. 7020 A.3 Quality Control has been revised to specify standard deviation information for QC charts. 7020 A.3d corrects the equation for the absolute difference. The update makes a number of minor editorial corrections to the text and the equations for normalized absolute difference and minimum detectable concentration.



Page last updated: April 21, 2025