Biofilms in recreational water

From the surfaces of our teeth, to the depths of the ocean, wherever there is water, you will find biofilm.  Biofilms have existed for millions of years, however, only recently have we have started to understand part of their role in impacting public health.  In this talk, the basic structure of biofilms, why we are concerned about them, and what can make them vulnerable to treatments will be discussed.  When microorganisms such as bacteria, fungi, and algae gather together on a surface and then coat themselves with slimy substances, they have formed biofilm.  Biofilm is not necessarily dangerous, and can be very useful in nature and wastewater treatment plants for nutrient removal from water.   However, it can harbor some dangerous pathogens.  Many bacterial pathogens such as Legionella pneumophila  and Pseudomonas spp. like to live in biofilms and will often thrive and reproduce quickly in a biofilm environment.  Once a biofilm becomes established on a surface, it can be very difficult to treat.  Although swimming pool and spa sanitizers are very good at killing microorganisms that are free floating in the water, it is difficult for them to get down through the slime layers of biofilm and kill all potentially harmful organisms.

Whichever approach is taken to control biofilm, any product that claims to remove, prevent, destroy, repel or mitigate biofilm is considered a pesticide by EPA and requires registration.  Therefore, just like sanitizers and algaecides, products that claim to be effective against biofilm must be EPA registered.  Biofilms have developed efficient survival mechanisms during their eons of evolution.  However, in order to protect public health in our pools and spas, it is important to remember that the single most important practice is to maintain an EPA registered sanitizer residual in all parts of the pool or spa at all times.  This will help prevent the formation of biofilm, as well as help kill pathogens that have been released from existing biofilms.