OC Spas Blog

February 24, 2017

LEGIONELLA AND HOT TUBS – What you need to know!

A hot tub is one of the most wonderful, therapeutic and lifestyle-enhancing home improvements that one can invest in.  However, it is important to ensure the water in your hot tub is clean, clear and hygienically safe.


Legionella is a type of aerobic bacteria that causes a potentially fatal infectious disease that affect the respiratory system.  The bacteria exist naturally in the environment.  It can be found in the mains water supply, where it can be safely swallowed.  Legionella grows best in temperatures between 25-45 degrees celsius, with an optimum growth temperature of 35 degrees – which is the temperature at which most spas and hot tubs are operated.  Warm temperatures also make it hard to keep disinfectants, such as chlorine, at the levels needed to kill germs like legionella.

Breathing in moist air that is infected with the bacteria can cause a person to contract the disease.  YOU DO NOT HAVE TO BE IN THE HOT TUB, Legionnaire’s disease can be caught by just standing by.  The bubble aeration in a spa makes this more likely to happen and there have been cases of Legionnaire’s disease that have been traced back to spas or hot tubs, although domestic showers are also a risk.



The legionella bacteria can either cause Legionnaire’s disease or a milder infection known as Pontiac fever.  People who contract Legionnaire’s disease may have a fever, chills, and a cough.  They may also have muscular aches, headaches, diarrhoea and feel confused and unstable, running a high temperature.  These symptoms may take 2-10 days to develop after exposure to the bacteria.

Pontiac fever develops more quickly- anywhere between a few hours and 2 days after exposure. Symptoms include fever, muscle aches but without pneumonia and other complications and normally recover without treatment in 2 to 5 days.

If you have any symptoms and think you may have been infected with legionella you should consult your doctor immediately and warn of the possibility.



Test the water daily, whether you are using it that day or not, and always before bathing.

Maintain the water balance maintained to BISHTA standards:   Chlorine or bromine levels at 2-4ppm for chlorine, or 3-6ppm for bromine.  PH levels between 7.0 and 7.6

Check the water more often when the spa is being used more often or by a larger number of bathers.

Keep the spa clean and free from dirt and debris and check and clean the filters on a regular basis, remembering to dry the cartridges after cleaning.  We recommend having 2 sets of filters; one in use and one drying after cleansing.

Always use good quality chemical products that are designed specifically for hot tubs.





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