This experiment was done to evaluate four different water sanitizers (sodium hypochlorite, calcium hypochlorite, iodophore and Biocid 30) using standard evaluation tests. The tested sanitizers were used in three different dilutions 2, 3 & 5%, and evaluated under conditions simulating those present in the environment. The obtained results reveled that although the phenol coefficient of the all tested sanitizers was the same un their germicidal power (5), yet the use dilution and capacity tests succeeded in evaluation between them, as sodium hypochlorite and iodophore were capable of destroying the tested microorganisms within 7 minutes in 3% concentration. Meanwhile there was no growth at all on using Biocid 30 (3%), while calcium hypochlorite failed to realize this result on the basis of use dilution test. The capacity of both sodium hypochlorite and iodophore was the same for 8 minutes only at 3% conc. but Biocid 30 had a capacity for 8, 18and even 28 minutes at that concentration (3%). Calcium hypochlorite had a capacity for 8 minutes only a 5% conc. On using capacity test. Although Biocid 30 realized this result, it failed to give any capacity on using at dilutions (1:1500, 1: 2500 and 1: 4000). The recommended dilution ofBiocid 30 (1:2500) realized 70% reduction in the total viable colony count of drinking water after 30 minutes exposure, meanwhile, this percentage reached 87.64% on using a dilution of 1: 1500 and its efficiency reduced (31.91%) reduction on using higher dilution (1: 4000).