We used to get water samples for this as well. However, we discontinued this practice. To test water one needs filtering apparatus to run a large amount of water through, then culture the filter pad to get an ID and colony count. To culture 10, 50 or 100mls of a water sample by inoculating with a loop or just taking .5 ml of sample is not adequate. They now send them to another lab that does this testing correctly. Environmental lab I believe.