The microfloro of a mineral water (Vittel Grande Source) has been studied after 0, 1, 3, 6 and 12 weeks storage in five kinds of bottle: (1) 1 litre glass, from a bottling line; (2) 1 litre glass, laboratory cleaned and sterilized, and filled by hand at the spring; (3) 1.5 litre PVC flasks taken from another line; (4) 1.5 litre PVC flasks taken after air blowing on the line and filled by hand at the spring; and (5) the same as (4) but rinsed once before filling, with the Grande Source water itself. We determined the numbers of total bacteria by an automated epifluorescence microscopic technique, the numbers of INT+ bacteria (able to reduce 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-2H-tetrazolium), and the numbers of colony forming units in nutrient agar, incubated at 30°C for 48 h. Of the bacteria isolated, we identified 1754 strains by classical procedures, and with API 20 NE strips for the Gram-negative rods. Immediately after bottling, an unexpectedly high number of bacteria was found (approx. 10 3 ml −1), most of which were minute and gave a weak green fluorescence after acridine staining. Thus a high sensitivity (Norticon) video tube had to be used for enumeration by the image analysing system. These minibacteria were probably dormant, and few (<0.01) were viable on agar. Whatever the type of bottle, multiplication started early and reached approx. 2 · 10 5 ml −1 by the 7th day, according to a typical saturation kinetics. In contrast to this, the colony forming ability was achieved later, and the transformation velocity depended on the type of sample; it was rapid in the PVC flasks filled on the line, slow in the glass bottles taken on the line, and intermediate in the bottles of PVC or of laboratory cleaned glass filled at the spring. The numbers of respiring (INT+) cells were not recorded at zero time ( t 0) but were found to remain constant or slowly decline from the 7th day to the 12th week. They were sometimes equalled but never exceeded by the numbers of viable bacteria. The species composition of the microflora at t 0 could not be determined precisely because of its scarcity. Afterwards, the viable microflora consisted for the most part (>80%) of five species ( Pseudomonas fluorescens, Acinetobacter lwoffi, Ps. alcaligenes, Ps. paucimobilis and Ps. vesicularis). Eleven other groups were identified, each accounting for < 1% of the viable microflora. The diversity was somewhat smaller in the samples taken from the bottling lines, because of a prevailing species Ps. paucimobilis in the glass bottles, and A. lwoffi in the PVC flasks. Finally, the use of epifluorescence microscopy has allowed us to describe a new proposal for the fate of bacteria in bottled water. From a preexisting flora of minibacteria, unable to grow on agar, an early multiplication of 7 or 8 generations occurs, regardless of the type of bottle. This leads to a population of approx. 2 · 10 5 ml −1 in 7 days. The rate of ability to give rise to culturable forms on agar depends on the mode of cleaning and filling of the bottles, rather than the material from which they are made.