The present study aimed to assess the abundance dynamics 2 spore forming bacteria of sanitary importance Bacillus cereus and B. thuringiensis, in the rain and groundwater in urbanized area in Cameroon (Central Africa) and potential impact of some abiotic parameters. The bacteriological analyzes were made by cultures on agar media and the chemical analyzes by spectrophotometry. It appears that heterotrophic aerobic mesophilic bacterial abundances ranged from 1x10 6 to 1x10 8 CFU/100µL in wells and from 9x10 6 to 196x10 6 CFU/100µL in rainwater. The abundances of B. thuringiensis reached 320 CFU/100µL in wells, and 730 CFU/100µL in rainwater. That of B. cereus reached 340 CFU/100µL in wells, and 12x10 2 CFU/100µL in rainwater. The pH of wells fluctuated between 5.05 and 7.33 whereas that of rainwater varied from 6.12 to 6.88. Electrical conductivity values ranged from 111 to 885 µS/cm in wells, and varied from 3 to 92 µS/cm in rainwater. Both media contains nitrate, nitrogen ammonia, phosphate, dissolved CO 2 and O 2 and their concentration undergoes spatio-temporal variations. Correlations coefficients between meteorological/chemical parameters and the bacterial abundance dynamics undergoes spatial variation on one hand, and varied according to a given abiotic parameter and the bacterial species considered on the other hand. The relationships between the properties of the previous month's rainwater on the abundance dynamics of the microflora in sampled wells during the current month, referred to as a delayed impact, showed a various degrees of influence, suggesting that the properties of the sampled groundwater would mainly result from the interactions of the confounding factors, and not only due to the rainfall or rainwater properties.