Recovery of micro-organisms from water is generally enhanced by incubation at low temperatures Incution temperatures as low as 10 have been used in combination with incubation times as long as 28 days In a quality assurance context however incubation at 20-22 for 5 days would seem to be adequate A second count on full strength medium incubated at 37 for 2 days may be con sidered useful in assessing contamination from sources other than the water itself