Legionella on the rise

Cases of Legionnaires’ disease are on the rise, it's time for installers to be vigilant when it comes to potential sources of legionella bacteria. 

Falling prices of hot tubs and spa baths, together with warmer weather, has created a perfect opportunity for legionella and other water-associated problems.

While those of us in the industry know that all man-made hot and cold water systems can provide an environment ripe for legionella bacteria to grow, the average consumer has no idea it can thrive in places such as hot tubs, whirlpool baths, compost heaps, and even garden hoses.

Legionnaires' disease is a lung infection you can catch by inhaling droplets of water containing viable Legionella bacteria from things like purpose-built water systems such as cooling towers, evaporative condensers, hot and cold water systems including tanks and cylinders, air conditioning, showerheads, taps, decorative water features and fountains, heating systems, spa pools & hot tubs. 

It can be very serious. 

The bacteria multiply where temperatures are between 20-45°C and nutrients are available. 

The bacteria are dormant below 20°C and do not survive above 60°C.

The growing popularity in domestic hot tubs and spa baths means that many families have a potential source of an outbreak within their homes and gardens. While the industry is working to raise awareness that these appliances need to be correctly installed, maintained, cleaned, and chlorinated.

Chlorine should be at 2 – 4 ppm (parts per million), bromine should be at 4 – 6 ppm, and pH at 7.2 – 7.8 ppm. 

Legionella is an intelligent bacteria, meaning it can adapt to the chemical, so it’s good advice to alternate using chlorine and bromine.

If it’s a hot tub you should change the water regularly, replace the filter as recommended by the manufacturer, and remove slime and other biofilm with regular cleanings.

Also keep the water moving via the pump and filters, legionella likes stagnant water, it will grow faster in stagnant water.

Many members of the public are blissfully unaware of the dangers.

Traditionally, outbreaks have hit commercial and industrial premises, such as that associated with a Bournemouth Health Spa in June of this year. However, it is looking likely that our industry will find itself dealing with more and more domestic outbreaks like the recurring incidence at Dolphin Square, and we need to be prepared.

Figures from Public Health England show a seasonal rise in cases from June to October. Crucially, last year saw an increase in reported/notified cases to 814, from which 532 were confirmed cases of Legionnaires’ disease. This represents an increase of some 20% on the previous year. 

Harmful legionella bacteria can incubate in as little as 2-10 days, meaning that those who let their hot tub and spa bath maintenance and disinfection regime slip, could very quickly be at risk. 

There is no legislation covering domestic hot tub installations. With annual deaths caused by poor plumbing now outnumbering those caused by carbon monoxide poisoning, we need to address the dangers that poorly designed or maintained systems can bring. The industry needs to be equipped with the knowledge and expertise to safely deal with potential legionella sources. It’s no surprise that poorly designed, installed and maintained systems are the most at risk.

For a Legionella risk assessment or legionella testing.

Experienced with Legionella risk assessments, knowledge of BS8-580, ACOP L8 and HSG274, have attended various legionella awareness courses and water treatment seminars.

City and Guilds BS4

Covering Horsham, Southwater, Broadbridge Heath and Billingshurst.