Section 9240 was little changed from the 1940s through the mid 1990s, when new sampling protocols and improved discussion of acidophiles were added. Significantly, de facto standard methods used in the ground water industry, especially the BART Method for detection of iron-related and sulfate-reducing bacteria, were not included in Section 9240 through the 21^st published edition, although such inclusion was called for much earlier.

The post-21^st-edition version of Section 9240 is extensively revised, with bacterial nomenclature and other terminology updated to match modern practice and various types of iron- and sulfur-manipulating groups and their effects better differentiated and described.  Collection sampling descriptions have been broadened, culturing methods updated, and both packaged culturing methods (e.g., BART) and biochemical methods included for the first time.  The method, submitted for ballot at the time this abstract was drafted, should now reflect modern actual standard practice and be more useful to the water community.