Q2: Why is acid added?

The acid controls the pH where the water contains lime of where calcium hypochlorite is used as a disinfectant. The pH is normally controlled between 7.2 and 7.6 pH units. Chlorine is less effective at higher pH: its killing power diminishes with rising pH.

Q3: What are the main hazards associated with leisure water?

Where there is poor control of disinfectant such as chlorine/ozone, micro-organisms will survive because there will be adequate amounts of food to sustain life in the leisure water. The main threats are presented by E. Coli, pseudomonas (earache and throat infections) and Staphylococcus aureus (ear, nose and throat infections). Maintaining the chlorine levels between 1 and 2 mg/L will kill most organisms but not cysts such as cryptosporidium or Giardia. These latter parasites are removed by efficient filtration systems.

Over chlorination can cause eyes to weep and high alkalinity can irritate the skin.

Q4: What about legionnaires and leisure water?

Where there is poor control of chlorine dosing legionnaires disease can strike. The organism, Legionella, is responsible and survives in stagnant water, which contains sufficient food to sustain growth. Breathing vapour with Legionella will almost certainly cause serious illness and could be fatal. There have been several cases of the disease recorded which resulted in serious illness or death. Smokers and the immunocompromised are most at risk. Showers can also present a problem. These should be managed so that water is not allowed to stagnate in supply tanks, pipelines and shower heads.