Legionella at beaches; what’s the risk?

Time for another instalment in our ‘What’s the risk?’ blog series! Today, Dynamika director Brett Wallace looks at legionella safety at beaches; and how things can go wrong in the sun…

Summer is rapidly approaching; in fact, for many of us across the UK, the sunny weather would suggest it’s already here!

And that means the beaches will soon be full of happy beachgoers; enjoying a good suntan or a paddle in the ocean.

But could the waves be harbouring a hidden danger in the form of legionella infection? Let’s find out…

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Does seawater contain legionella?

The good news is, legionella generally isn’t keen on the sea.

While studies have shown that legionella bacteria can survive in marine environments, large concentrations of sodium (such as those found in sodium hypochlorite bleach) will kill off the bacteria.

The Atlantic, North Sea and English Channel all have a salinity (or salt level) of around 3.5%; generally enough to kill (or at the very least disable) the legionella bacteria.

That’s not to say that seawater can’t pose a serious health hazard. Besides the obvious risks of drowning and being swept out by currents, seawater contaminated by sewage outflow can cause deadly infections if it’s ingested by swimmers.

In 2022, a woman almost died from contracting E.coli at a beach in Pembrokeshire where an untreated sewage spill had taken place.

Back in the year 2000, a similar case at a beach in Devon saw the tragic death of an 8-year old girl.

How can legionella grow and spread at beaches?

Legionella much prefers freshwater environments; and counterintuitively, it’s here where the bacteria can pose a greater risk to beachgoers.

Where are you likely to find freshwater on a beach?

Well, how about public showers? These facilities can provide the ideal conditions for legionella growth and spread (among other nasty bacteria, viruses and fungi):

• Showers naturally produce a spray of aerosolised water (which is, of course, how legionella gets into our lungs and causes Legionnaires’ disease)
• They’re located outdoors, where the sun’s warmth can push them into the 20°C to 45°C danger zone
• Their proximity to the sea and to the salty sea air can leave pipework vulnerable to rust and corrosion (which provides food for the bacteria to feast on and grow)
• Shower cubicle walls/barriers can help to enclose and concentrate airborne water droplets; which increases the risk of spreading infection if those droplets happen to be carrying the bacteria
• Public showers require regular maintenance, which may be a neglected area for some landowners and local authorities
• Showers often sit unused for extended periods outside the summer months, where residual water inside pipework can stagnate and become a shelter for bacteria; waiting to spread when the sun comes out again

A 2007 study in Italy took samples from 36 different beach shower facilities, and found that 7 of those samples were contaminated with Legionella Pneumophila; the very strain responsible for the vast majority of Legionnaires’ disease cases.

Other outdoor public water facilities at the beach (including taps, drinking fountains and bottle refill stations) can pose similar risks.

What are the responsibilities for beach owners and local authorities in preventing legionella?

The law surrounding legionella control at beaches – and of beach safety in general – is quite vague and tangled.

The Health and Safety at Work Act (HSWA) and Control of Substances Hazardous to Health (COSHH) both place a legal duty of care on ‘employers’ and ‘those who control premises’ (including outdoor spaces) to protect staff and visitors from the risks of legionella.

In other words, private beach landowners and local authorities operating public ‘amenity beaches’ all have a duty of care. The Occupiers’ Liability Act also requires beach landowners to protect visitors’ safety.

The Environment Agency monitors beach seawater and other bathing waters to ensure their safety and prevent the spread of bacterial nasties like E.coli; with polluters held responsible for serious health hazards.

As far as we could tell from our research, however, legionella in seawater is not monitored. It also appears that the HSWA doesn’t apply to the sea itself.

This is likely because – as we covered earlier – the seawater itself doesn’t really pose a major risk for legionella.

Showers and other hot/cold water systems at the beach, however, definitely fall under these pieces of legislation.

And don’t forget, the fines for neglecting your health and safety duties can run into the tens of thousands!