The study evaluated the levels of pathogenic bacteria present in the rearing water and meat of cultured oysters found along selected coastal areas of the municipality of Iloilo, Philippines. Eight types of bacteria were present in oysters’ meat and rearing water namely: Escherichia coli, Vibrio sp., Salmonella sp., Shigella sp., Citrobacter sp., Klebseilla sp., and Proteus sp. The number of bacteria in rearing water of three selected coastal areas of the municipality of Iloilo ranged from 7,700 – 20,600 CFU/100ml of E. coli; ranged from 19.800-21,000 CFU/100ml of Vibrio sp.; and 3,800 – 18,600 CFU/100ml of Salmonella sp. and Shigella sp. These results of pathogenic bacteria are beyond the allowable threshold. Escherichia coli in oyster meat ranged from 16,500 – 25,250 CFU/100grms; Vibrio sp. ranged from 12,700 – 26,700 CFU/100grm. ; Salmonella sp. and Shigella sp. ranged from 5,200 – 28,000 CFU/100grm. These results of pathogenic bacteria in oysters’ meat are beyond the allowable threshold. Moreover, this study ascertained the efficiency of an eco-friendly and cost efficient depuration systems namely: biofilter tank, mechanical filter tank, flow through tank and tank using UV sterilizer. During 12-48 hours, results showed that tank using UV sterilizer depurated oyster to a passable standard level for consumption. In 24 hours, biofilter tank, mechanical filter tank and flow through tank depurated oyster from E. coli to a passable standard level for consumption. Further in 36 hours, biofilter tank depurated oysters from Salmonella sp. and Shigella sp. Furthermore in 48 hours, biofilter tank depurated oyster from E. coli, Vibrio sp. and Salmonella sp. and Shigella sp. to standard level for consumption. Keywords-Depuration, Crassostrea iredalie, bacteria, bivalve, mollusks, pollution, Philippines