Public drinking water treatment systems vary in age, quality and contaminants removed, but the government's primary goal is to reduce the risk of waterborne illnesses.

While the goal of a personal drinking water purification system may be to reduce that risk even further, while protecting one's future health.

You see, drinking water treatment systems may target any number of contaminants or only a single one.

For example, a disinfection method must be used for most public sources, as well as some private wells and springs.

Microscopic organisms of all varieties live and flourish in liquids.

So, diseases including bacterial, parasitic and viral infections can be transmitted through the water that a person drinks.

However, disinfection (which is an absolute necessity in this day and time) at public drinking water treatment systems creates another health hazard, regardless of the method used.

Those health hazards are referred to as disinfection by-products or DBPs.

There are over 600 different DBPs, according to researchers for the Environmental Protection Agency.

Many of them fall under the heading of trihalomethanes or THMs.

You will see THMs listed on a performance data sheet for a home drinking water purification system.

At one time, there was some debate about whether or not exposure to THMs was a health hazard, at all.

At first, researchers said that THM exposure might increase a person's risk for cancer, but now we know that a large number of new cases ever year are attributed to THM exposure.

In the United States, the EPA requires that drinking water treatment systems measure the amount of THMs present at their facility.

There is, what they consider, a maximum safe level, but no one really knows for sure.

The EPA's goal is actually to inform the public that the compounds are present.

That way, an individual can take measures to protect him or herself.

The best way to do that is with a home drinking water purification system.

A drinking water purification system called adsorption is required to remove THMs and other disinfection by products.

Activated carbon blocks or granules remove varying amounts of the contaminants, so you have to check product performance data, before you buy.

Otherwise, a drinking water purification system could be just a waste of money.

Some of the point-of-use or home drinking water treatment systems on the market today are really nothing more than chlorine filters.

Chlorine is bad for the digestive tract and spoils the taste and smell, but a filter that removes it does not necessarily remove THMs.

Also, it is important to know that THM exposure can come from showering and using unfiltered water for cooking.

Those who swim in chlorinated pools increase their exposure.

Several studies have shown that THM exposure in pregnant women causes birth defects.

So, not only should you consider a personal drinking water purification system, but also a showerhead or whole house filter.

Environmental groups hope that advancements can be made in public drinking water treatment systems, but right now, as long as you protect your home with the right filtration devices, you don't really have to worry about it.