Most community water purification systems obtain their water from surface sources, like rivers, lakes, and reservoirs. These bodies, open to the environment, are susceptible to pollution. Animal waste can contaminate surface sources with bacteria like Giardia and Cryptosporidium. Industries can discharge their wastes into surface water, adding hazardous organic contaminants to the source you may drink. Storm water drains can empty into rivers and lakes with rainwater that's carrying gasoline, oil, and any number of hazardous and bacterial wastes. Rainwater can also carry fertilizers and pesticides from fields into streams, rivers, lakes, and reservoirs. Even train derailments and truck accidents that cause tankers to spill their contents can contaminate surface sources.

Cryptosporidium in particular is difficult for treatment facilities to eliminate. Each Cryptosporidium microorganism is covered by an outer shell, called a oocyst, that is impervious to disinfection chemicals like chlorine. On rare occasions, these oocysts pass untreated through treatment plants to your home.

In 1993, the City of Milwaukee experienced a severe Cryptosporidium outbreak. The parasite passed through the treatment and disinfection process and caused over 400,000 people to contract cryptosporidiosis, a gastrointestinal disease that can be fatal to people with a compromised immune system. More than 4,000 people were hospitalized, and more than 50 people died. The original source of contamination is uncertain.

Chlorine itself is another potentially harmful chemical. While it is vital to disinfection, chlorine can bond with naturally occurring organic matter to form potentially harmful substances, such as chloroform.

Other substances that can enter your drinking supply are rust, sediment, and even lead. While flowing through distribution pipes from the treatment plant to your home, it can pick up these pollutants after it's already been treated.

So how do you find out what's in your source? The best way is to call your community system and ask for a quality analysis. You can compare the results to EPA's National Primary Drinking Standards and National Secondary Standards to find out if it falls below levels EPA thinks are safe for certain contaminants. As of 1999, your community system will have to send you yearly reports with this information.

A note of caution: a test will only tell you what is in the liquid that day. Public treatment plant failures can occur intermittently, and pollutants can be present after these failures or after other events (e.g., after farm fertilizing periods, heavy rains, or season changes).

Knowing what's in your source will help you select one of our purification systems. If it is high in rust and/or sediment, or if you wish to reduce odors and chlorine in all your faucets, showerheads, and appliances, we recommend installing a Whole House filter. If you are concerned about bacteria, lead, or volatile organic compounds (VOCs), we recommend additionally installing an Undersink filter. Or if you just want great tasting refreshment, we also recommend installing an Undersink filter.

People who use private wells are not immune from problems either.

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