Microplastics in Australian tap water: what the evidence shows

1. Microplastics are found almost everywhere scientists look, including bottled water.
2. The WHO says there's no reliable evidence of harm at current levels, and not enough data to be sure.
3. Conventional water treatment removes most particles before water reaches you.
4. If you want fewer particles, match the filter's micron rating to the size you care about.

What are microplastics?

Microplastics are small plastic particles, usually defined as smaller than 5 millimetres, that come from larger plastic breaking down or from products like synthetic fabrics and tyres. Particles smaller than one micrometre (a thousandth of a millimetre) are often called nanoplastics. The WHO lists the main routes into water sources as surface run-off (e.g. after a rain event), to wastewater effluent (both treated and untreated), combined sewer overflows, industrial effluent, degraded plastic waste and atmospheric deposition.

What the WHO's 2019 review found

In August 2019 the World Health Organization published Microplastics in drinking-water, its first review of the evidence. Its headline conclusion was measured. As WHO put it at the time: Based on the limited information we have, microplastics in drinking water don't appear to pose a health risk at current levels.

The review was equally clear about what it couldn't say:

• On the particles themselves, it found insufficient information to draw firm conclusions on the toxicity related to the physical hazard of plastic particles, particularly for the nano size particles, while noting that no reliable information suggests it is a concern.
• On the research, it warned that most studies are not fully reliable because their methods lacked sufficient quality control.
• On size, it noted larger particles (over 150 micrometres) are unlikely to be absorbed by the body, while data on nano-sized particles is extremely limited.

WHO called for more research and less plastic pollution, rather than for people to change how they drink water.

What do we know in Australia?

The most-cited Australian study looked at bottled water, not tap water. Researchers from the University of Melbourne tested 16 bottled water brands from Australian supermarkets and detected microplastics in 94% of samples, at an average of 13 ± 19 particles per litre and up to 80 per litre. Imported brands carried about four times more than Australian-sourced ones.

For tap water, published, quality-controlled Australian data is limited. Australian utilities test their water against the Australian Drinking Water Guidelines, which do not currently set a value for microplastics. That's not the same as saying they're absent. It means no one has set a number to measure against yet.

What the evidence does and doesn't show

So we won't tell you your tap water is full of plastic, or that microplastics are making anyone sick. What we can say honestly is that water picks up particles between the treatment plant and your glass, and a filter gives you control over the last step.

What filtration captures, by micron

Filters are rated by the smallest particle they reliably stop. Bigger number, bigger gap. This is the practical way to think about microplastics: match the filter to the particle size you want to catch.

Ratings are typical ranges; "nominal" ratings catch most, not all, particles at that size. Check the product data sheet.

WHO notes that advanced treatment such as nanofiltration can remove particles larger than 0.001 micrometres, and reverse osmosis is tighter again. That's why, if microplastics in drinking water worry you, a reverse osmosis drinking tap is the most effective single step. Some filters also carry certification listing microplastic reduction. If a seller makes that claim, ask to see the certificate that lists it.

What to ask anyone selling a microplastics filter

Microplastics are an easy fear to sell. Before you pay for a filter on that basis, ask:

• What is the micron rating, and is it nominal or absolute? A nominal 5 micron cartridge catches most particles at 5 microns; an absolute rating is a tighter promise.
• Which certificate lists microplastic reduction? If there isn't one, the claim is the seller's opinion.
• What does it do to flow? Finer filtration across the whole house needs larger housings to keep pressure up.
• How often does it need changing, and what does that cost? Fine cartridges load faster.

And be wary of anyone who says your tap water is "full of plastic" or that it's making your family sick. The evidence doesn't support either claim.

What we'd suggest

For the whole house, a fine sediment stage catches particles before they reach the shower and appliances. For drinking water, a reverse osmosis tap such as our mineral drinking tap goes to membrane level. You don't need to fear your tap. You can just choose what reaches your glass. See what your filter catches for how each stage compares.

Questions

Plumbing and installation details reviewed by a licensed plumber. See our editorial policy.