Because of the rapid and often extensive changes which may take place in
the bacterial flora of bottled samples when stored even at temperatures
as low as 10° C., it is urged, as of importance, that all samples be
examined as promptly as possible after collection.
The time allowed for storage or transportation of a bacterial sample
between the filling of the sample bottle and the beginning of the
analysis should be not more than six hours for impure waters and not
more than twelve hours for relatively pure waters. During the period of
storage, the temperature shall be kept as near 10° C. as possible. Any
deviation from the above limits shall be so stated in making reports.