Soaking in a hot tub is a relaxing way of spending leisurely time, especially with friends. This is why so many hotels, as well as spas and gyms, have hot tub facilities for their guests. However, a spa-pool or hot tub is used by many different people, often at the same time, which means that special attention needs to be paid to the quality of the water.
Hygiene is hugely important when so many people are sharing the same water. The Health and Safety Executive has produced detailed guidelines on the legal obligations of those responsible for the control of hygiene and infection in spa pools under the Health and Safety at Work etc Act 1974 as well as the Management of Health and Safety at Work Regulations 1999 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH).
The particular focus of health and safety guidance is legionella bacteria, a pathogen which, if inhaled, could go on to develop into the potentially deadly Legionnaires’ disease.
When it comes to a spa-pool, the optimum water temperature for humans (30oC) is also the optimum water temperature for legionella bacteria (20oC-45oC). When humans use a spa-pool, they introduce contaminants in the form of sweat, dirt, body lotions, deodorants, washing powders etc. Poorly cleaned hot tubs could also have areas of stagnant water where algae can take hold.
This means that if the water in the pool is not treated properly, the temperature of the water will encourage the growth of legionella bacteria, and the contaminants will give the bacteria something to feed on, resulting in unsafe levels in the water.
Conditions are made even more favourable to legionella bacteria by the water jets in the hot tub. The splashes caused by the jets produce tiny aerosol droplets of water that are easily inhaled by people using the hot tub or who are close by. If the water is contaminated by legionella bacteria, they are taken directly into the lungs where they can thrive. Once established, they’ll develop into Legionnaires’ disease, a chest infection that causes pneumonia-like symptoms and breathing difficulties.
Instances of people catching Legionnaires’ disease after using hot tubs are thankfully few and far between. The worst outbreak occurred in 1999 at a Dutch flower show which originated from two infected whirlpool spas. In total, 188 visitors and exhibitors became ill, of which 163 were hospitalised with suspected Legionnaires’ disease - with 17 confirmed cases, including four fatalities.
It doesn’t matter how diligent you are in treating the water in your hotel or spa’s hot tubs, the build-up of contaminants will eventually prove too much for the chemical sanitisers, rendering them less effective. Only recently, a Japanese hotel manager apologised after it was revealed his staff only changed the water in their spa bath twice a year. Nor did they add chlorine to the water because the staff “disliked the smell”. As a result of this poor practice, the level of legionella bacteria found in the water was 3,700 times higher than the permitted level.
By following HSE Guidelines on cleaning and maintaining your spa-pool system, and changing the water on a weekly basis, you will keep your facilities clear of legionella bacteria and therefore prevent an outbreak of Legionnaires’ disease.