Legionella contd...

Legionella can be controlled in spas by ensuring constant adequate disinfectant levels. If disinfectant levels are inadequate, where levels drop below 0.3mg/l, up to a third of all spas will test positive for Legionella. The standards set in “Managing Spa Pools – Controlling the risk of infection” published by the Health Protection Agency is 3-5mg/l for chlorine and 4-6 mg/l for bromine. Available by download from the Health Protection Agency (HPA) website "Management of Spa Pools-Contolling the the Risks of Infection"HPA Website link

If a spa pool tests positive for Pseudonomas Aerunigosa (PsA), it also has a 30% chance of testing positive for Legionella. This is especially prevalent in bromine disinfected spas when in a recent survey 85% of Bromine dosed spa pools showed signs of contamination with legionella where as only 15% of chlorine dosed pools where contaminated.

Legionella and PsA amongst others, will be found in heavy biofilm deposits. Biofilms are natural phenomena caused by micro-organisms forming a colony with a hard outer skin; the outer skin is relatively impervious to disinfectants and can only be removed by either harsh chemical treatment or physical abrasion. Biofilms are a common occurrence in spa filters. Microbiological contamination can be detected using dipslides and an incubator or using instant ATP testing equipment. These tests can be carried out in-house by a competent plant operator or contracted out. If the dip slide shows signs of microbiological activity the spa should be tested by a professional microbiologist. Meanwhile the spa pool and spa plant should be thoroughly cleansed.< Previous Next >