The treatment centers are doing the best that they can, but there are just too many issues in today's environment. Things like herbicides and pesticides. Now, we hear about drugs and hormones.

Not long ago it was lead, from aging pipes and solder joints. And, of course, since chemical disinfection is one step in practically every public water filtration system, we have to worry about chlorine and its by-products. The list just keeps growing.

I took the time to evaluate a number of different technologies that have been adapted to fit a home water filtration system. Most contain activated carbon, which is good at removing chlorine. It was used in masks in World War I to counter the affects of chlorine gas, a chemical weapon. Activated carbon granules can trap some other chemicals, too, but alone, it cannot do the whole job.

A multi-media block, usually containing carbon and copper, will trap many different chemicals on its surface, along with toxic metals like lead. A micron filter in a water filtration system will remove microscopic particles, like cysts.

Cysts are immature bacterium that "floats" into the pipes and the reservoirs. They are almost like eggs, in that they have a tough outer coating. They are resistant to chemical disinfection, so the treatment facilities cannot remove them.

Maybe the worst one is cryptosporidium. That parasite caused the death of over 100 people in Milwaukee. It is usually present in areas where farm run off enters the public reservoir, but since it can be present anywhere that there is animal waste, it could be in your area, too. This is why they ask us to pick up after our dogs, but you see people who don't pay attention.

The only way to be safe is to use a water filtration system that is certified for cryptosporidium and guardia cyst removal. They are the two most common. Both types grow on animal feces. Both cause intestinal distress and diarrhea. They are most dangerous to the very young, the very old and those who are already ill, because their immune systems cannot fight off the infection.

Last but not least, an ion exchange stage in a water filtration system will balance the mineral content and pH, making it healthy to drink and fresh tasting. Some purifiers, like distillation and reverse osmosis remove all mineral content, which is not good for your digestive system. Balanced is better.

Other than looking at the technology, the best way to judge is by comparing certified product performance data. It will list things like chlorine, lead, cysts, VOCs, THMs, MTBE and specific weed and bug killers.

But if you look for a complete that combines activated carbon, multi-media block, micron filtration and ion exchange then you'll be covered. It's the best technology and the best value for your money.