The influence of different storage conditions (temperature, illumination, brand of mineral water and storage time) on growth of mould spores was studied. Alternaria alternata, Penicillium citrinum and Cladosporium cladosporioides spores were inoculated in bottles of mineral and mineralised water, packaged in polyethylene terephtalate (PET). The bottles were incubated under different storage conditions. The strains had been isolated from bottled mineral water in a previous study. Storage time was the parameter that had the most important influence in mould growth. The spores grew into visible colonies after 5 month of incubation in bottles just filled, and in a month in bottles that had been stored for 5 month. This could be due to the migration of compounds from PET packaging material into mineral water. This compounds could be used as nutrients (organic matter) for mould growth. The plasticizer additive di-n-butyl phthalate (DBP) concentration in recently bottled mineral water and in 5-month stored bottles was measured. An increase of 20% of DBP concentration was observed. A. alternata and P. citrinum strains were toxicological characterised. Both strains produced mycotoxins in vitro, and P. citrinum produced citrinin in mineral water, posing a potential health risk for consumers.