The waves of scientific evidence are gathering. Will a century of chlorine dependence withstand independent scrutiny?
A beachfront home may look magnificent from the road: sweeping balconies, imposing walls and uninterrupted ocean views. But when waves begin to wash away the ground beneath it, the real question is no longer how impressive the building looks. It is whether its foundations can hold.
Nearly 2,000 years ago, the parable of the wise and foolish builders made the same point. One house was built on rock; another on sand. The difference became clear when the storm arrived.
Enviroswim believes the swimming pool industry faces a comparable test. For generations, its practices, training, standards and commercial systems have been built around chlorine. But is that foundation being examined with the same scientific rigour now expected of newer treatment technologies?
Chlorine has a history. That is not the same as a permanent scientific exemption.
Chlorine has made an important, well-established contribution to water disinfection and public health. Under suitable conditions, it kills or inactivates many microorganisms. Those facts should not be denied.
Yet effectiveness is not a single, unchanging property. In swimming pools, chlorine performance depends on water chemistry, temperature, pH, organic contamination, contact time and the presence of stabilisers.
A measured free-chlorine concentration tells an operator something important about the water. On its own, however, it is not a direct test of how rapidly particular microorganisms are being inactivated.
If public health is the objective, should we not ask for evidence of actual microbiological performance under realistic operating conditions—not simply evidence that a chemical residual is present?
The problem hidden behind a reassuring chlorine reading
Cyanuric acid is widely used in outdoor pools to protect chlorine from degradation by sunlight.
That benefit comes with a trade-off: it changes the chemical equilibrium governing the amount of immediately active hypochlorous acid in the water.
In our submissions concerning draft Australian Standard AS 3633:2026, we drew attention to conditions under which cyanuric acid levels of about 30–50 mg/L can leave only a small proportion—of the order of 1%—of measured free chlorine present as immediately active hypochlorous acid.
The precise fraction depends on the conditions. The balance of chlorine is not simply useless: it can replenish the active fraction as that fraction is consumed. But the chemistry can affect the speed of disinfection.
This is not merely Enviroswim’s concern.
The US Centers for Disease Control and Prevention explains that cyanuric acid can increase the time needed for chlorine to inactivate pathogens, including Cryptosporidium. Its guidance also recognises that some pathogens can persist in otherwise properly chlorinated water.
A compliant chlorine reading should not be confused with proof that all relevant microorganisms will be controlled within a particular time.
That distinction deserves more prominence in pool standards, training and public information.
What independent Enviroswim testing demonstrates—and what it does not
Enviroswim has spent more than 25 years developing Australian swimming pool sanitation technology that combines treatment mechanisms beyond conventional chlorine dosing.
We have sought independent testing rather than relying on assertions about performance.
In May 2004, the Tweed Laboratory Centre examined the Enviroswim treatment configuration against Pseudomonas aeruginosa in 1,500-litre spa-pool experiments.
Its reported results included:
- 4.895-log reduction after 30 seconds in one experiment.
- 4.96-log reduction after 30 seconds in a separate experiment.
- Approximately six-log reductions after two minutes.
Total chlorine before testing was reported below 0.01 mg/L.
These are significant laboratory results for the tested configuration and organism.
They do not prove universal performance against every pathogen, under every pool condition, and the experiments were not a direct side-by-side comparison with a conventional chlorinated spa.
Any certification or NSF/ANSI 50 testing must likewise be understood within its specific scope.
The point is straightforward: when an alternative technology has independently documented microbial inactivation results, those results deserve an assessment on their merits.
The performance criteria should be clear, rigorous and appropriate to the whole treatment system.
What did the APVMA Freedom of Information response establish?
In 2014, Enviroswim asked the Australian Pesticides and Veterinary Medicines Authority (APVMA) for specified efficacy documentation relating to three registered pool sanitiser products, including conventional chlorine products.
The APVMA advised that documents fitting the scope of the request did not exist.
It explained that the particular efficacy guidelines in question applied to applications or reviews beginning on or after 1 July 2014, and the products had not undergone the relevant qualifying processes.
This finding does not prove that chlorine lacks disinfecting power, nor does it establish that the registrations were unlawful.
It does raise a fair question:
How are longstanding approvals reassessed as science advances, and are established and emerging technologies scrutinised against consistent, publicly understandable evidence requirements?
Disinfection must address chemical exposure as well as germs
Chlorine reacts not only with microorganisms but with substances introduced into pool water by bathers and the environment.
Some reactions form disinfection by-products, including chloramines and trihalomethanes.
Researchers have investigated the respiratory, irritation and other potential health implications associated with different by-products and exposure conditions.
The risks vary by compound and circumstance, and scientific associations should not automatically be presented as proven causes.
Nonetheless, these by-products are real consequences of water-treatment chemistry.
A sound public-health approach must consider both effective control of infectious organisms and the minimisation of unnecessary chemical exposures.
Neither objective should be ignored.
A standard should rest on evidence—not replace it
The current proposed revision of Australian Standard AS 3633 offers an opportunity to reassess those foundations.
Enviroswim has lodged detailed public submissions on cyanuric acid, microbiological performance, alternative technologies and the need for technology-neutral requirements.
We support demanding safety standards.
But a standard is strongest when its prescribed requirements can be traced to transparent evidence, when potential conflicts are appropriately managed, and when a different technology can demonstrate equivalent public-health protection by suitable independent tests.
A century of commercial familiarity is not a scientific test.
Nor is criticism of an established practice evidence of wrongdoing by any regulator, standards body or business.
It is a reason to examine the underlying data carefully, openly and consistently.
If the foundations are sound, show the evidence. If they are not, have the courage to rebuild them.
The waves are coming. Which foundation will the industry choose?
The erosion threatening coastal buildings is a striking image.
Repairs to balconies, barriers and walls may be useful—but they cannot answer the question of what is happening beneath the structure.
In the swimming pool industry, revised dosing instructions and updated standards are no substitute for continual scientific reassessment.
The evidence must address performance in real water, operational reliability, bather loading, pathogen diversity, the effects of cyanuric acid, unwanted reaction products and the full public-health risk.
Enviroswim is not asking anyone to accept our technology on trust.
We are asking for all treatment systems—chlorine-based and alternative—to be judged by independent evidence, relevant safety outcomes and consistent standards of proof.
The industry does not have to abandon its history to examine its foundations.
But it does have to be willing to question what it has long taken for granted.
The waves of scientific evidence are gathering. The question is whether the swimming pool industry will inspect its foundations before the next storm.
Read the evidence and submissions
Enviroswim submissions on draft AS 3633:2026
Standards Australia accountability and correspondence
CDC guidance: responding to faecal incidents in pool water
CDC publication on recreational-water outbreaks and cyanuric acid
Enviroswim Pty Ltd
Australian-owned and manufactured swimming pool sanitation technology.