A Guide to Filter Micron Ratings: 1 Micron vs 5 Micron vs 20 Micron

Micron ratings appear on almost every filter cartridge, but the practical difference between, say, a 1 micron and a 20 micron filter is not always obvious at a glance.

What a Micron Rating Measures

A micron is a unit of measurement equal to one millionth of a metre, and the rating indicates the smallest particle size a filter is designed to capture.

Coarser Filtration: 20 Micron and Above

Filters in this range are generally used as a first-stage pre-filter, catching visible sediment, rust particles, and debris before finer filtration stages.

Mid-Range Filtration: 5 Micron

A 5 micron filter captures much finer sediment and some larger bacteria and cysts, commonly used as a second stage in multi-stage systems.

Fine Filtration: 1 Micron and Below

At this level, filters can capture very fine particles and some parasitic cysts, though this level of filtration also restricts flow more, which is why it is usually paired with adequate housing size.

Why Multi-Stage Systems Use a Range

Using progressively finer micron ratings across multiple stages protects finer filters from being overwhelmed by coarser sediment, extending the working life of the whole system.

The Engineering Behind A Guide to Filter Micron Ratings: 1 Micron vs 5 Micron vs 20 Micron

Understanding a guide to filter micron ratings: 1 micron vs 5 micron vs 20 micron comes down to a handful of measurable engineering factors: micron rating (the physical pore size of the filter media, typically between 0.5 and 20 microns for residential systems), flow rate (litres per minute the system can sustain without a noticeable pressure drop), and media type (sediment, carbon block, catalytic carbon, KDF, or membrane). Each of these interacts with your home’s plumbing, incoming water pressure, and household demand to determine real-world performance.

Reputable manufacturers publish independent test data for these specifications rather than relying on generic marketing claims. When comparing systems, look for components that are WaterMark certified for plumbing compliance in Australia and, where a specific contaminant reduction claim is made (such as chlorine taste and odour, cysts, or PFAS), verify it against the NSF/ANSI standard the claim is tested to.

Verified Standards & Further Reading

For homeowners who want to verify the certification claims made in this article, we encourage you to check the primary sources directly rather than taking any supplier’s word for it (including ours):

• Search any plumbing product’s WaterMark certification status directly on the Australian Building Codes Board’s official WaterMark product database.
• Verify NSF/ANSI certified water treatment products and the specific standard they are tested against via the official NSF certified product listings.
• Read the current Australian Drinking Water Guidelines published by the National Health and Medical Research Council for the official national standards on drinking water quality.

All AquaCo filtration systems supplied and installed by Vic Water Filters carry WaterMark Licence No. 23448 and are independently tested to the relevant NSF/ANSI standards for their stated contaminant reduction claims, including PFAS/PFOA and PFOS reduction where specified on the individual product datasheet.