The Science of Australian Water

1. Your water leaves the treatment plant clean. But what happens on the way to your tap?

When we think about water quality, it's natural to assume it all comes down to the treatment plant. After all, water supplied by Australian utilities meets strict safety standards.

But there's a question few people ask:

Once the water leaves the public network, what happens between there and the tap in your house?

It was precisely that stretch of the journey that caught the interest of Australian researchers.

One study analysed 212 water samples collected directly from kitchen taps in homes across New South Wales. The results showed that almost every sample contained detectable copper, while 56% contained detectable lead. In 8% of homes, the lead concentration exceeded the limits set by the Australian drinking water guidelines.

The biggest surprise wasn't finding metals in the water. It was finding out where they came from.

According to the researchers, the main source wasn't the water distributed by the public system, but the taps, fittings and plumbing components inside the homes themselves.

The Australian Drinking Water Guidelines, published by the NHMRC, reinforce that concern. The body explains that older homes may have taps, fittings and solder made from materials no longer in use today. It also notes that lead concentrations can rise when water sits in the pipework for long periods, which is why many people run the tap for a few seconds before using it.

These findings lead to an important point.

The quality of the water distributed to a city is not necessarily the quality of the water arriving at each household tap. The plumbing inside each property is part of that journey too.

While exposure depends on concentration and contact time, studies show that prolonged lead exposure can affect brain development in children. High copper concentrations over time can also place strain on the liver in susceptible people.

Knowing the water quality in your area is an excellent first step. Understanding the plumbing in your own home can add to that picture and help you make more informed decisions.

References
https://www.sciencedirect.com/science/article/abs/pii/S0013935116303280
(Study: “Widespread copper and lead contamination of household drinking water, New South Wales, Australia” — Environmental Research, 2016. Analysis of 212 samples from NSW homes.)

https://guidelines.nhmrc.gov.au/australian-drinking-water-guidelines/part-5/physical-chemical-characteristics/lead
(NHMRC — Australian Drinking Water Guidelines: lead in household systems.)

2. Australian towns have been told to boil their water. Did you know?

When we think of Australia, it's natural to picture one of the safest water supply systems in the world. And the country does have strict standards for monitoring and controlling water quality.

Even so, there are situations where the authorities themselves advise people not to drink tap water without boiling it first.

It may sound surprising, but this happened in a number of Australian towns during 2025.

Among the areas that received official NSW Health alerts were Terrigal, North Avoca, Avoca Beach, Copacabana and MacMasters Beach in February. In March, the warnings covered Bilambil Heights and Terranora. In June, Scone and Aberdeen remained under alert for more than a month.

In most cases the reason was the detection of E. coli in the supply system, an indicator of possible faecal contamination and a risk of gastrointestinal illness. In other cases, alerts were issued because of cyanobacteria, known as blue-green algae, which can produce toxins harmful to people and animals.

It's important to understand that these episodes don't mean the Australian supply system is unsafe.

They show precisely the opposite.

The alerts are part of a rigorous monitoring protocol. Whenever there is any possibility that water quality has been compromised, the public is told immediately and given guidance to reduce the risk until the situation is resolved.

These records show that water quality can change temporarily for a range of environmental or microbiological reasons. That's why continuous monitoring remains one of the main tools for protecting public health.

Reference
https://www.health.nsw.gov.au/environment/water/Pages/drinking-water-quality-and-incidents.aspx
(NSW Health — Drinking Water Quality and Incidents. Official page with an up-to-date history of alerts.)

3. When water changes colour and smell. What's going on?

You turn on the tap and notice the water looks greenish, smells different, or just seems off.

The first reaction is usually to assume something is wrong with the plumbing in the house.

But in some cases the explanation lies well before the water ever reaches your home.

Blue-green algae, known scientifically as cyanobacteria, occur naturally in rivers, lakes and reservoirs right across Australia. Under normal conditions they're simply part of the ecosystem and pose no problem.

That changes when high temperatures, reduced water flow and excess nutrients allow them to multiply. In those conditions you get what's called a bloom, an intense proliferation that can alter the colour, the odour and even the safety of the water.

The phenomenon is monitored constantly by Australian government bodies.

SA Health regularly tracks the situation in the Murray River and the Torrens River, while the Victorian Department of Health monitors regions such as the Gippsland Lakes, where intense blooms can temporarily make both the water and some local seafood unsafe.

Depending on the species involved, some cyanobacteria produce toxins that can cause nausea, vomiting, diarrhoea, headaches and skin irritation after contact with the water.

For that reason, blue-green algal blooms are among the main causes of water quality alerts in Australia, alongside contamination episodes involving bacteria such as E. coli.

The most important thing to understand is that these events don't go unnoticed. They're part of what the authorities responsible for water supply actively monitor, so preventive measures can be taken whenever they're needed to protect the public.

References
SA Health — Blue-green algae: risks, monitoring and public guidance.

Victoria Health — Health effects of blue-green algae.

NHMRC — Section 5.6, Cyanobacteria, Australian Drinking Water Guidelines.

4. Chlorine protects your water. So why do so many people try to filter it out?

Chlorine has saved millions of lives around the world.

It might seem odd to open an article about filtration by saying that, but it's the truth.

It was chlorine disinfection that brought waterborne diseases, once responsible for major epidemics, under control in many countries, Australia included.

So let's be clear about one thing: chlorine isn't the problem. It's part of the solution.

Its job is to protect the water for the whole journey between the treatment plant and the tap in your house, reducing the risk of contamination by micro-organisms.

Which raises an interesting question.

If chlorine is so important, why do so many people look for ways to reduce it at the moment they use the water?

The answer is what's known as residual chlorine.

Having done its job across the supply network, a small amount is still present when the water reaches your home. According to the Australian Drinking Water Guidelines published by the NHMRC, that residual chlorine can affect the taste and odour of the water. Some people also report a drying sensation on the skin and scalp after showering.

That doesn't mean the water is unfit to drink.

It simply means there's a difference between keeping water protected during distribution and providing a more pleasant experience at the moment it's used.

For that reason, many families choose to use filtration systems directly at the points of use, such as taps and showers. That way chlorine does its job across the supply system and can be reduced only at the moment the water arrives at the house.

It's an approach that tries to balance two important goals: keeping water safe while it's distributed, and improving the experience for the people who use it every day.

Reference
NHMRC — Australian Drinking Water Guidelines, Version 4.0, section on chlorine disinfection.

5. Heavy metals can cause symptoms easily confused with many other conditions.

Constant tiredness, frequent headaches or trouble concentrating are usually put down to stress, a demanding routine or poor sleep.

But there's a possibility few people consider.

In some situations, prolonged exposure to certain metals can also be related to those symptoms.

Lead, mercury, arsenic and cadmium can enter the body in small amounts from a range of environmental sources: food, occupational activities, pollution and, in some situations, water.

The real challenge is that this exposure tends to happen slowly.

In most cases there's no single moment where a person notices something has changed.

Symptoms appear gradually and are often similar to those of many other health conditions.

They can include persistent fatigue, headaches, difficulty concentrating, abdominal pain, tingling in the hands and feet, and changes in kidney or liver function where exposure is significant.

That doesn't mean these symptoms indicate heavy metal contamination.

It simply means that where exposure is suspected, it should be investigated by a health professional.

That's exactly what the heavy metals blood test is for.

In Australia, laboratories such as PathWest, run by the Western Australian government, offer this kind of analysis. The test can measure substances including lead, mercury, arsenic and cadmium, supporting a doctor's clinical investigation.

Australian health bodies set reference values and specific protocols. In the case of lead, for example, results above certain levels must be notified to health authorities.

The test doesn't produce a diagnosis on its own. It has to be interpreted by a doctor alongside clinical history, possible sources of exposure and other tests.

The main message is simple.

When there's doubt, the best decision isn't to guess. It's to investigate.

Knowledge always leads to better choices.

References
PathWest, Government of Western Australia — heavy metals testing for health and workplace use.

MedlinePlus — technical explanation of the heavy metals blood test, referencing the Australasian Association for Clinical Biochemistry and Laboratory Medicine.

6. How UV light inactivates bacteria, viruses and protozoa without changing the water you drink

When we look at a glass of clear water, it's natural to believe it's completely free of contaminants. Bacteria, viruses and protozoa, however, are invisible to the naked eye and don't change the colour, taste or smell of water.

It was precisely to deal with that kind of contaminant that ultraviolet light technology, known as UV, came into use in water treatment systems around the world.

The way it works is precise and silent.

When a micro-organism passes through the UV chamber, the ultraviolet radiation reaches its DNA and RNA, stopping it from reproducing. The micro-organism doesn't instantly disappear from the water, but it loses the ability to multiply, which makes it unable to cause infection in the same way.

For that reason, UV disinfection has been used for decades as a safe and effective method in drinking water treatment.

Scientific studies demonstrate its effectiveness against bacteria such as E. coli and Listeria, as well as viruses and protozoa such as Cryptosporidium and Giardia, organisms that can be involved in waterborne gastroenteritis.

Another important advantage is that UV light does this without adding chemicals, without changing the taste, odour or composition of the water, and without creating disinfection by-products.

There is, however, one point worth noting.

UV light has a very specific function. It acts only on microbiological contaminants such as bacteria, viruses and protozoa. It does not reduce heavy metals, sediment, chlorine or dissolved minerals.

That's exactly why the most complete filtration systems combine different technologies. While some filter media work on reducing sediment, chlorine or particular chemical contaminants, UV light adds a further layer of protection against invisible micro-organisms.

Each technology does a different job. Together they offer a more complete approach to treating water.

References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9895992/
(Peer-reviewed study: “Impact of UV-C Irradiation on Bacterial Disinfection in a Drinking Water Purification System”, 2023. Confirms the effectiveness of UV-C light against E. coli and Listeria in domestic purification systems.)

NHMRC — Australian Drinking Water Guidelines. Complementary treatments used in filtration systems.