Let's be clear
Queensland-based Allan Cockerell has been offering specialist consulting engineering services on large public swimming pools and their water treatment plants for over 35 years. He is an advocate for better industry education on the dangers of disinfectant by-products in swimming pools.
In his three-plus decades in the pool industry, Allan Cockerell has seen more than his fair share of pools with inadequate water treatment plants and knows only too well the problems this poses. He's the first to admit that the issue is extremely complex, so it's no surprise that industry professionals may not be aware of the full scope of the problem.
“Eight years ago, the Center for Disease Control in the United States identified an increasing incidence of ill health associated with swimming pool use," he said. “They funded a thorough review and published a set of industry guidelines, which took over seven years to develop. The result is a 600-page document released in August last year, which shows just how many things you have to get right if you want to reduce the risk of illness and disease."
The risks aren't as high in a domestic setting, given the typically light load in a backyard pool. As Cockerell points out, a busy day probably means four or five kids swimming, but the average load in public facilities is another thing altogether. Throw 300 kids into a learn-to-swim environment and it won't take long for problems to appear.
“The problem is that you simply don't see the contaminants," said Cockerell. “A number of years ago, I had to investigate an aquatic centre that featured three pools. I discovered that none of the filters were actually capable of backwashing the water and this had been the case for 20 years. When presenting my report I included a photo of one of the pools on a sunny day, water glistening and looking very inviting. I asked how many people would rather be in the pool than sitting in a room listening to me give my findings. Naturally, most of them said they would. That changed as soon as I showed them a photo of the top of the pool filter's sand bed. Believe me, 20 years worth of accumulated saliva, hair and other contaminants doesn't look that appealing and by the look on their faces they were shocked."
There's way more at stake, however. Disinfectant by-products come about when the chosen disinfectant (usually chlorine) reacts with compounds in the pool. Some of these by-products, including trichloramines and trihalomethanes, have been identified as the cause of many respiratory problems and startling new research shows that indoor swimming pools are also linked to scoliosis — curvature of the spine.
According to Cockerell, this link is likely to be gas related, as trichloramines tend to congregate just above water level. Indoor pools are obviously more susceptible to issues because the gases are contained. Even with the introduction of air conditioning and ventilation systems, there are still problems and many industry members simply aren't aware.
“Looking at your average indoor pool, fresh air is being introduced via large ducts about three or four metres from the ground, well away from the water level. The air that is being extracted is coming from a similar height, but it's nowhere near the problem area," said Cockerell. “I was involved in the design of a facility where we took air off the pool water through the wet-deck channels, so there was a much higher chance of removing the nasties, but it was an expensive exercise and why would you do it if you didn't know the issues existed in the first place?"
Cockerell sees a number of factors contributing to the lack of awareness. “First up, Australian Standards don't provide any guidance on filters," he said. “Most people will focus on the state-based guidelines and figure that meeting with those is enough. I've seen many commercial facilities that are fitted with water treatment plants designed for residential use and they simply can't handle the load in a public facility. It's way more common than you would think."
Additionally, as ageing public pools around Australia start to fail, many councils are opting to consolidate several outdoor facilities and redevelop large-scale indoor aquatic centres. There are many points of influence in the design and a lack of understanding from various parties can lead to insufficient water treatment and ventilation solutions being implemented, putting the public at risk of illness.
Cockerell is usually called on once a problem presents, such as sand discharging from the filter into the pool, but said councils could benefit from utilising better specialist engineering services at the design phase, preventing issues rather than trying to address problems at a later stage.
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