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Shake the sample violently in one of the collecting bottles, when it is half to two-thirds full and when the sample is at room temperature (about 20° C.). Remove the stopper and smell the odor at the mouth of the bottle.

Pour about 150 cc. of the sample into a 500 cc. Erlenmeyer flask. Cover the flask with a well-fitting watch glass. Heat the water almost to boiling on a hot plate. Remove the flask from the plate and allow it to cool not more than five minutes. Then agitate it with a rotary movement, slip the watch glass to one side, and smell the odor.

Express the quality of the odor by a descriptive epithet like the following, which may be abbreviated in the record:

a—aromatic

C—free chlorine

d—disagreeable

e—earthy

f—fishy

g—grassy

m—moldy

M—musty

P—peaty

s—sweetish

S—hydrogen sulfide

v—vegetable.

Express the intensity of the odor by a numeral prefixed to the term expressing quality, which may be defined as follows:

Numerical value. Term. Definition. 0 None. No odor perceptible. 1 Very faint. An odor that would not be detected ordinarily by the average consumer, but that could be detected in the laboratory by an experienced observer. 2 Faint. An odor that the consumer might detect if his attention were called to it, but that would not attract attention otherwise. 3 Distinct. An odor that would be detected readily and that might cause the water to be regarded with disfavor. 4 Decided. An odor that would force itself upon the attention and that might make the water unpalatable. 5 Very strong. An odor of such intensity that the water would be absolutely unfit to drink. (A term to be used only in extreme cases.)