Whole House Water Filter Sizes: Which Dimensions Do You Need?

Choosing the right size whole house water filter matters more than most people realise. Too small and you’ll get pressure drop and premature cartridge clogging. Too large and you’re spending more than you need to. Here’s a practical guide to the key dimensions and which one suits your home.

Browse our full whole house filter range or see our Whole House Water Filters Guide for more detail.

Understanding Filter Housing Dimensions

Whole house filter housings are described by two measurements: length x diameter. The most common sizes in Australia are:

Note: flow rates are indicative. Actual flow depends on your mains water pressure, pipe diameter, and plumbing layout. When in doubt, size up — a larger housing won’t hurt performance but a too-small one will.

Our Big Blue Whole House Filter Range

Single Stage Big Blue — 10" x 4.5"

One housing, one cartridge. Ideal for homes that need sediment or chlorine removal as a single stage. Compatible with 4.5" x 10" cartridges including sediment, carbon block, and dual-stage options. Good entry-level whole house solution for smaller households.

Twin Big Blue — 10" x 4.5" (each housing)

Two housings in series — typically Stage 1 sediment + Stage 2 carbon block. Removes sand, rust, sediment, chlorine, chloramines, and heavy metals. Includes heavy-duty metal bracket and 1" x 3/4" bushings. The most popular configuration for Australian family homes.

Triple Stage Big Blue — 10" x 4.5" (each housing)

Three housings in series — typically 5-micron sediment + carbon block + 1-micron sediment. Handles up to 75 L/min. Includes 1" brass threaded ports. Best for larger homes, double-storey properties, or where water quality requires more comprehensive treatment. Protects tap washers, hot water systems, and appliances throughout the home.

How to Choose the Right Size

• 1–2 people / unit / townhouse: 10" x 2.5" or single stage 10" x 4.5"
• Family of 3–5 / standard house: Twin Big Blue 10" x 4.5" — the most common choice
• Large family / double-storey / low pressure: Triple stage or 20" x 4.5" housing
• Bore or tank water with high sediment: Triple stage with 20" x 4.5" housings for maximum cartridge life

Not sure which size suits your home? Call us on 1800 789 781 and we’ll recommend the right configuration based on your household size, water source, and pressure.

Frequently Asked Questions