Friday, 14 July 2017

A timely reminder about the importance of properly maintaining a hot tub

According to BISHTA, the trade association that represents the British and Irish Hot Tub and Swim Spa Industry, the estimated number of hot tubs in the UK is around 100,000 with 6,000 being sold annually.

Given the sales of hot tubs and the recent news of a hot tub warehouse being fined £1 million after it was found to be responsible for a Legionnaires’ disease outbreak which killed two men; we thought it would be timely to blog about the importance of correctly maintaining a hot tub.
Legionnaires’ disease is a type of pneumonia caused by the legionella bacterium. This disease can be serious if not treated immediately, but you can easily guard against the disease by monitoring the water in your hot tub and by making sure that your hot tub is kept clean.

Hot tubs pose a ‘reasonably foreseeable’ risk of Legionnaires’ disease because the water is kept at a temperature of between 30 and 35 degrees, close to body temperature, which is the ideal environment for legionella bacteria to grow.

The bubbling and frothing of the aerosols in a hot tub can then throw the bacteria into the air for several metres around the tub, which if inhaled can make their way into the lungs potentially infecting them with Legionnaires’ disease.

Although Legionnaires’ disease can be fatal it is also treatable. However, Legionnaires’ disease is preventable with appropriate maintenance of your hot tub.

Firstly and most importantly, always follow the manufacturer’s recommendations for appropriate management and maintenance of a hot tub, because cleaning and maintaining the hot tub regularly is the only way to ensure that bacteria do not concentrate in the water and the spray.

In terms of what maintenance is required, BISHTA recommends the following steps.
  • Purchase a spa test kit capable of checking chlorine levels
  • Use the kit to check the disinfectant and pH levels before each use
  • Maintain disinfectant levels: chlorine at 3 ppm and bromine at 3 ppm.  Maintain the pH of water between 7.0 and 7.6
  • Maintain total alkalinity at: 80 to 160 ppm
  • Superchlorinate (shock) the hot tub regularly using chlorine. Become familiar with the hot tub shock process by consulting your manual or spa/pool supply store
  • Drain and clean the hot tub after shocking
  • Clean the hot tub by vigorously scrubbing all surfaces with a chlorine solution such as household bleach, to remove any biofilm or slime. Biofilm protects bacteria from disinfectants. Rinse the tub after cleaning
  • Clean or replace filters according to your hot tub instruction manual
  • Refill hot tub and do not use until all chemical levels have returned to normal
  • Ensure your hot tub circulates the water periodically when it is not in use. This is vital to help prevent contamination of hot tub pipes with disease causing organisms

More detailed information on maintenance can read at

APHC administers a Legionella Risk Assessment and Disinfection Scheme where members are qualified to undertake legionella risk assessment and remedial work. You can source an APHC member at

Happy soaking!

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