The summer of 2007 proved to be a nightmarish one for many public recreational water facilities across the United States. Reports of recreational water illnesses (RWls) appeared in media headlines from June to September. In Utah alone, Cryptosporidium (Crytpo) sickened more than 1,800 people over the summer. Across the state, pool attendance fell by 46,000 participants and revenues dropped by $84,000 between August and October. It seems despite all the attention, education, and new technology available, a solution to the problem of recreational water illness remains elusive.
Proper Chlorine Levels
There are many different pathogens (disease-causing agents) that may be present in swimming pool water. Some germs are enteric, meaning they cause illness when ingested. Enteric diseases from pool water mainly come from organisms such as E.coli, Giardia, Cryptosporidium, and Shigella. These organisms are introduced to the pool from sick swimmers who unknowingly defecate in the water. Warm-blooded animals such as dogs or deer can contaminate the area as well. Contaminated soil tracked in by swimmers can cause more problems. Diseases may be present in the droppings of birds. Swimmers who ingest the water can become ill with mild to severe gastroenteritis, which causes mild to severe stomach problems and diarrhea.
Gastroenteritis-related illness are the most common pool outbreaks, according to the Centers for Disease Control and Prevention (CDC) and Crypto is the most widely reported cause of gastroenteritis in recreational water. Severe cases can cause death in small children and the elderly.
The total number of reported cases of Crypto increased from 3,505 in 2003 to 3,911 in 2004, and to 8,269 in 2005. Compared with other age groups, a greater number of case reports were received for children ages 1 to 9 years and adults ages 30 to 39 years. Peak onset of illness occurred annually during early summer through early fall.
Other germs present in pool water are classified as non-enteric, and are not transmitted through fecal matter. These are largely responsible for skin, eye, ear, and respiratory problems. Some examples of non-enteric diseases are Psuedomonas, Legionella (Legionnaires' disease), and several types of skin infections.
Most disease-causing organisms thrive when the facility is not properly maintained. This is especially true in situations with incorrect water balance and sanitizer levels. Poor maintenance is often the result of operator error or faulty equipment.
In one outbreak of E.coli at an Atlanta waterpark in 1998, it was discovered that the chlorine levels were low. Unfortunately, this occurred during a very hot day when the pools were full of swimmers. A report from Georgia state health officials explains that low chlorine levels at the water park contributed to the E.coli outbreak that killed two children and sickened more than two dozen others.
E.coli can be easily handled when chlorine sanitizer is in the correct range between 1 and 3 parts per million (ppm). Many health departments may allow even higher residuals to keep bacteria inactivated in pools. For most germs, chlorine at proper levels still remains one of the most effective ways to keep pool water safe.
When chlorine sanitizer is used against contaminants in pool water, there are varying CT (contact time) values required to disinfect specific types of pathogenic micro-organisms. For example, the protozoa Giardia has a CT value of 45 minutes at 1 ppm of chlorine. This means that Giardia is inactivated in 45 minutes of contact with pool water carrying a 1 ppm residual of chlorine.
The Difficult Germ
Dr. Jeff Williams is a microbiologist with pool products company SeaKlear. "You have a set of organisms that should never cause a problem, but they do on a regular basis because people don't keep the sanitizer in the right range or other conditions in the pool, or the water is not optimal for the sanitizer to work," he explains. …