How Does a Whole House Water Filter Work? An In-Depth Guide
August 19, 20213 min read
A whole house water filter connects to your main water supply line and treats every drop of water that enters your home — every tap, shower, appliance, and garden hose. Here’s a clear explanation of how they work and which filtration method suits your water quality.
Cartridge Filters (Most Common for Australian Homes)
One or more replaceable filter cartridges sit inside a housing connected to the main water line. Water passes through the cartridge, which removes contaminants, then flows to every tap in the house. Cartridges need replacing every 2–12 months depending on type and water quality.
Our Big Blue range uses this format — available in single, twin, and triple stage configurations. Simple to maintain, no drain connection required, and suitable for most Australian town water supplies.
Backwashing (Media) Filters
A large tank filled with loose filter media (such as activated carbon, zeolite, or manganese dioxide). The system periodically backwashes — reversing water flow through the tank to flush accumulated contaminants to drain. Media lasts several years before replacement. Requires a drain connection and power for the control valve. Better suited to bore or tank water with high sediment or iron loads.
Filtration Methods Explained
Sediment Filtration
Removes suspended particles — sand, silt, dirt, rust, and scale — using a physical barrier. Typically the first stage in a multi-stage system, protecting downstream filters from premature clogging. Essential for bore water, tank water, and older homes with corroding pipes. Sediment cartridges are rated by micron size — a 5-micron filter removes particles 5 microns and larger.
Activated Carbon Filtration
The most widely used filtration method for Australian town water. Activated carbon has millions of tiny pores that adsorb chlorine, chloramines, VOCs, pesticides, herbicides, and taste/odour compounds. Carbon block filters are more effective than granular activated carbon (GAC) for most contaminants. This is the primary stage in our Big Blue whole house systems.
UV Sterilisation
Ultraviolet light disrupts the DNA of bacteria, viruses, and parasites (including Giardia and Cryptosporidium), rendering them unable to reproduce. UV doesn’t add chemicals or alter taste. Essential for bore water, tank water, or any supply where microbial contamination is a concern. UV is typically installed as the final stage, after sediment and carbon filtration.
Ion Exchange
Exchanges unwanted ions in the water for less harmful ones. Water softeners use ion exchange to swap calcium and magnesium (hardness) ions for sodium or potassium ions. Reduces scale buildup in pipes and appliances, and improves the feel of water on skin and hair.
Oxidation Redox (KDF)
KDF (Kinetic Degradation Fluxion) media uses a copper-zinc alloy to remove chlorine, heavy metals, and hydrogen sulfide through a redox reaction. Effective at higher water temperatures, making it useful in shower filters and hot water applications. Also inhibits bacterial growth within the filter media.
What System Do You Need?
Most Australian homes on town water need a sediment + carbon cartridge system — this removes chlorine, chloramines, sediment, and taste/odour compounds effectively. Our twin and triple Big Blue systems cover this in a single installation.
For bore or tank water, add UV sterilisation as a final stage. For hard water, add an ion exchange softener. For high iron content, a manganese dioxide backwashing filter is most effective.
Not sure what’s in your water? Call us on 1800 789 781 and we’ll help you choose the right combination for your water supply.
Frequently Asked Questions
Does a whole house water filter remove fluoride?
Standard carbon cartridge filters don’t remove fluoride. For fluoride removal at every tap, you need a reverse osmosis system at the point of use, or a water distiller. See our Reverse Osmosis Guide.
How often do whole house filter cartridges need replacing?
