Most public utilities do not test for the presence of cryptosporidium. Although lead is not usually found in the water supply coming from treatment plants, it can end up in the water we drink. Faucets and fixtures also contain lead. Faucet manufacturers settled a lawsuit out of court in California to get the lead out of faucets by 2000. Hopefully, manufacturers will make the lead-free faucets available outside California.
Chlorine is a great bacteria and virus killer.
It protects health up to the point of consumption. These are created when the surface water sources, such as Lake Lanier and the Chattahoochee River, accumulate organics like decayed leaves and animal waste, then mix with the chlorine at the water treatment plant. These THMs are known carcinogens. But THMs can increase in the distribution pipes, especially if chlorine is added later in the distribution system. Pesticides such as chlordane, used for years for termite control and toxins like PCBs and dioxins.