Waterborne diseases are typically considered to be those diseases resulting from ingestion of contaminated water. Additional pathways of infection include inhalation of water vapors as well as body contact during bathing (opportunistic pathogens) in the hospital environment.

The transmission of diseases through water is one of the primary concerns for a safe water supply. This can be illustrated by the following quote of the Director-General of the World Health Organization WHO, Dr. LEE Jong-wook: "Water and sanitation is one of the primary drivers of public health. If we can assure access to clean water for all people, irrespective of the difference in their living conditions, a huge battle against all kinds of diseases will be won".

Less than 100 years ago, typhoid fever and amebiasis were the main causes of waterborne illnesses and deaths in the western world. Thanks to contemporary water treatment measures, we have defeated illnesses like typhoid fever, cholera, and dysentery. But new threats have emerged in our waters. Microbial contamination of water may be rare, but it can and does occur, causing illness and even death. Hospital-acquired infections are a worldwide problem especially in hospitals for the treatment of acute cases. These infections are among the leading causes of death.

The following groups of micro organisms have been linked with the occurrence of waterborne diseases.

Disinfection and filtration are the most common methods of eliminating pathogens from drinking water. All Filtrix products are based on capillary hollow fibre membranes, the only safe and reliable barrier to microorganisms. Filtrix has a complete line of Legionella prevention products, especially for the Health Care Market.

Bacteria are the most widely distributed life forms. Pathogenic bacteria range in length from approximately 0.4 to 14 µm (a µm or "micron" equals one one-thousandth of a millimeter) and 0.2 to 1.2 mm in width. Key bacterial pathogens responsible for waterborne disease include Legionella, Salmonella typhi, Shigella, and Vibrio cholerae.

Probably the most feared bacteria of our time are the Legionella pneumophila that can cause Legionnaires disease, a lung infection (pneumonia). Among critical groups like elderly people and immune-compromised patients this lung infection may even lead to death. Legionnaires' disease is caused by bacteria that belong to the family Legionellaceae. This family now includes 48 species and over 70 serogroups. Approximately half of these species have been implicated in human disease. Legionella pneumophila is responsible for approximately 90% of infections. Most cases are caused by L. pneumophila, serogroup 1. Legionella species are small (0.3 to 0.9 µm in width and approximately 2 µm in length) faintly

Viruses are inactive when outside of a living host cell. Viruses linked to waterborne disease have protein coats that provide protection from environmental hazards and range in size from 0.02 to 0.09 µm. Unlike bacteria and protozoa, they contain only one type of nucleic acid (RNA or DNA). Key pathogens include the hepatitis A, Polio and Norwalk virus.

Protozoa, common in bodies of water, are much larger than bacteria and viruses. To survive harsh environmental conditions, some species can secrete a protective covering and form a resting stage called a "cyst." Encystment can protect protozoa from drinking water disinfection efforts and facilitate the spread of disease. Key protozoa being studied as agents of waterborne disease include Giardia and Cryptosporidium. Disinfection and filtration are the most common methods of eliminating pathogens from drinking water. All Filtrix products are based on capillary hollow fibre membranes, the only safe and reliable barrier to microorganisms. Filtrix has a complete line of Legionella prevention products, especially for the Health Care Market.

To make water potable, a large number of contaminants may have to be removed. The compounds of interest range from micropollutants like pesticides, detergents and chlorinated solvents to suspended solids and residual oxidants such as ozone. Activated carbon, one of Norit's major purification products, plays a vital role in the removal of all kinds of organics from drinking water. Activated carbon, in fact, is the key to make water clean and safe enough to drink.