Whole House Water Filter Replacement Parts: What You Need & When

A whole house water filter is low-maintenance — but it does need regular cartridge replacements to keep working properly. Here’s a practical guide to the parts you’ll need, when to replace them, and how to choose the right cartridge for your system.

Browse our whole house replacement cartridge range or call us on 1800 789 781 if you’re not sure which cartridge fits your system.

Key Replacement Parts & Intervals

Sediment Pre-Filter Cartridge

The first stage in most whole house systems — removes sand, silt, rust, and large particles before they reach the carbon stage. Replace every 2–6 months depending on your water quality. Bore and tank water users will need to replace more frequently. Signs it’s due: reduced water pressure or visible discolouration in the cartridge.

Carbon Block Cartridge

Removes chlorine, chloramines, VOCs, and taste/odour compounds. Replace every 4–6 months. Signs it’s due: returning chlorine taste or smell in the water.

Sub-Micron Post-Filter

An optional final stage that removes very fine particles and some protozoa that earlier stages may miss. Replace every 9–12 months. Most relevant for bore water, tank water, or water supplies with known microbial concerns.

O-Ring

The rubber seal between the housing bowl and cap. Inspect at every cartridge change — replace if cracked, deformed, or if the housing develops a persistent leak. Always lubricate with food-grade silicone grease before reinstalling. Most housing kits include a spare O-ring.

Housing Bowl

Not a regular replacement item, but plastic bowls have a finite service life: clear bowls every 5 years, blue/opaque bowls every 10 years. See our Housing Replacement Guide for more detail.

How to Choose the Right Replacement Cartridge

Step 1: Check Your Housing Size

Standard whole house cartridge sizes are:

• 2.5" x 10" (slim line)
• 2.5" x 20" (slim line long)
• 4.5" x 10" (Big Blue standard)
• 4.5" x 20" (Big Blue long)

Check your system’s manual or measure the existing cartridge (width across the top, length from end to end) to confirm your size.

Step 2: Know What You’re Filtering

Choose the cartridge type based on your water quality concern:

• High sediment (bore/tank water): 5-micron or 10-micron polyspun sediment cartridge
• Chlorine/chloramine removal (town water): carbon block cartridge
• Both sediment and chlorine: dual-stage sediment + carbon cartridge, or separate stages
• Fine particle removal: 1-micron post-filter cartridge

Step 3: Micron Rating

Lower micron ratings remove finer particles but reduce flow rate and require more frequent replacement. For most Australian town water applications, a 5-micron sediment pre-filter paired with a carbon block is the standard configuration. For bore or tank water with high sediment, start with a 20-micron or 50-micron pre-filter to extend the life of the finer downstream stages.

Frequently Asked Questions