BIOFILMS

        What are Biofilms? Biofilms are generally thin layers of microorganisms that have attached to and grow on surfaces. Not only do biofilms consist of organisms, they also are comprised of pieces of metals from pipe corrosion, organic and inorganic matter, and microorganism by-products that bind the colony together (called extra-cellular material). Biofilms can grow in water distribution mains, indoor plumbing, within water fixtures (i.e. shower heads and faucets) and on surfaces.

        Biofilms can consist of a variety of organisms at any one time, some that can cause illness, particularly in individuals with suppressed immune systems.

        How Does a Biofilm Form? A biofilm forms when sufficient numbers of an organism enter a water system (through either a treatment deficiency, new construction, or other manner) and settle into a location where attachment and growth is possible. Factors that promote biofilm growth include corrosion (provides crevices for attachment), nutrients, elevated temperatures, and low disinfectant levels.

        Likely locations for biofilm growth include large buildings, particular those with recirculating hot water systems, and towards the end sections of distribution systems. Hospitals, due to the high density of immunocompromised individuals, are key locations where biofilm-associated pathogens have been found.

        Why are Biofilms a Concern? The concern with biofilms is not necessarily from the organisms in the film, but from organisms that slough away from the biofilm and enter the main water stream. Some of these organisms can be pathogenic.

        What Threat are Biofilms to My Health? Biofilms can contain a host of different microorganisms that have potential health significance. Most notable ones are Legionella pneumophila and Mycobacterium avium complex which are discussed in other fact sheets. These organisms can grow within a biofilm and then slough away into the water stream where they can either be ingested or inhaled (i.e., aerosols from showers and humidifiers). Often no disease symptoms will result. On occasion, however, health effects range from gastrointestinal illness (from ingestion) to pneumonia (from inhalation of aerosols).

        How Can I Protect Myself? If you are immunocompromised you should consider additional protective steps such as boiling your drinking water for one minute, which will kill any bacteria in it. You could also use a water filter certified by NSF International to remove particulate matter, 1 to 5 microns in size (ClassII), or drink only bottled water certified by NSF or drink only canned and bottled bubbly drinks.

        In using a home water filter, it is critical to replace or clean the filtering mechanism per the manufacturers instructions. If filters are not change or cleaned regularly, the filter itself can be colonized by biofilm microorganisms and begin to pose a health threat.

        Flushing drinking water taps in your home for 30 seconds each morning will help to minimize biofilm growth in your indoor plumbing. When away for several days, taps should be flushed for several minutes before consuming tap water.





Source: http://www.ci.sf.ca.us/puc/wqfs/outbreak.htm