Analysis of the water quality in a municipal indoor swimming pool

Bath has been a part of human history for a long time. Today bathing/swimming in municipal pools is for people of all ages and it is possible to take swimming courses, exercise or enjoy recreation. The municipal indoor pool of Hogdalen in Sweden was build in the sixties and has had problems with high levels of heterotrophic bacteria. The facility has two larger pools, one adventure park for young kids, two smaller bath tubs and a jacuzzi. To improve water quality UV light and coal filter were installed in October 2009 to the already existing purification system. The water purification starts with a mechanical grid followed by flocculation and then through a sand filter before pH adjustment and chlorine. To adjust water levels in the pools drinking water is added when needed. Chlorine is a common and effective disinfectant but are also known to react with organic material and form disinfection by products (DBP) which decreases the disinfection level and could be a health problem. The goal of this essay is to evaluate the technology that was installed in October 2009. Investigations of laboratory data, comparing data before and after with a one way anova test, do not show a significant improvement of heterotrophic bacteria and free chlorine but TOC, DBP and total chlorine have improved significantly. The conclusion is that UV-light and coal filter effectively decreased levels of DBP and TOC in the pool water of Hogdalen. High levels of heterotrophic bacteria before October 2009 was a result of free chlorine forming chlorinated byproducts with organic material which led to low levels of free chlorine. After October 2009 the level of free chlorine was not high enough to disinfect the water properly because of adjustment problems to new technology. Total chlorine levels have decreased after October 2009 which makes it possible to add more chlorine. Although heterotrophic bacteria did not decrease as expected the improvement of DBP levels decreases health risks for both swimmers and employees staying in the pool area