On the basis of data reported in literature concerning the saprophytic bacterial flora of natural mineral waters bottled in glass or in PVC containers and in view of the results obtained during their own investigations, the AA. consider it impossible to establish a limit to the charge of bacterial flora in agar at 20 degrees C and believe that any possible proposal concerning rules limiting the bacterial charge at 37 degrees C requires more detailed study and preliminary controls. In any case, they propose to apply the strictest vigilance in excluding the presence of any sign whatever of fecal contamination or of potentially pathogenic bacterial types (f.i. P. aeruginosa) in all water samples; they also suggest to require that the performance of comparative tests be extended to the stages preceding bottling. Current experimental investigations reveal that the multiplying process seems to be accelerated and more protracted in time in waters bottled in PVC containers than in those kept in glass containers.