Whole House Filter | 3 Stage | 20" x 4.5" | Big Blue | WaterMark

Clean, filtered water from every tap, every shower, every appliance in your home — this is the only whole house water filter system you'll ever need to install. The Enviro Aqua Premium Three Stage Big Blue Whole House Water Filter System is WaterMark certified to AS/NZS 3497, built from 304 stainless steel, and engineered to handle the full water demand of an Australian family home without any drop in pressure.

This is not a portable bench top unit or a basic inline filter. This is a permanent, mains-connected whole-home filtration system that a licensed plumber installs once on your main water supply line — and then every litre of water entering your home is filtered before it reaches a single tap.

Why This System

1. WaterMark Certified — The Only System Your Plumber Can Legally Install

Under the Plumbing Code of Australia, any water filter permanently connected to a mains water line must carry WaterMark certification. This system does. A licensed plumber can legally install it on your main supply line, issue a certificate of compliance, and your installation is fully covered. Most cheaper systems sold online are not WaterMark certified — your plumber cannot legally install them on a mains line, and your home insurance may not cover you if they fail.

2. Big Blue 20″ × 4.5″ — No Pressure Drop, Longer Cartridge Life

"Big Blue" refers to the 4.5″ diameter filter housings — nearly four times the filter media volume of standard 2.5″ housings. This matters in two critical ways. First, water flows through at up to 75 litres per minute with no perceptible pressure loss, even when multiple showers, taps, and appliances run simultaneously. Second, the larger volume of filter media means cartridges last significantly longer before replacement, reducing your annual running costs. Three 20″ × 4.5″ housings with 1″ BSP brass inlet and outlet ports — the correct size for Australian mains supply lines — complete the package.

3. 304 Stainless Steel Enclosure — Built for Australian Conditions

The 304-grade stainless steel enclosure isn't just about looks — though it does look sharp. It is specifically engineered for Australian outdoor and garage installations. 304 stainless is UV-resistant, salt-air resistant, and corrosion-proof: the chromium-nickel alloy forms a self-renewing protective layer that resists the coastal humidity, summer heat, and UV exposure that corrode powder-coated steel and degrade plastic components over time. If you're in a coastal or high-humidity location, this matters enormously. It's also tamper-resistant, protects the filter housings from physical damage, and presents cleanly on an external wall or in a visible garage location.

Three-Stage Filtration — What Each Stage Does

Stage 1 — Sediment Pre-Filter (5 Micron)

The first stage captures sediment, rust, sand, silt, and suspended particles down to 5 microns. This is the workhorse stage — it intercepts the physical debris in your water supply before it can clog the more specialised carbon stages downstream. Protecting the carbon stages from sediment load is what makes a three-stage system significantly more effective and longer-lasting than a two-stage system with carbon alone.

Stage 2 — Carbon Filtration (Chlorine, Chloramine, Taste & Odour)

The second stage uses a granular activated carbon (GAC) or catalytic carbon cartridge to remove chlorine, chloramines, taste, odour, trihalomethanes (THMs), and a broad range of chemical contaminants. If your water supply uses chloramine — which includes Sydney Water, Melbourne Water, SA Water, Urban Utilities (Brisbane/SEQ), and Icon Water (Canberra) — specify a catalytic carbon cartridge for Stage 2. Standard GAC carbon cannot reliably remove chloramine at whole-house flow rates; catalytic carbon can, and the 20″ × 4.5″ housing provides the contact time needed for it to work effectively.

Stage 3 — Carbon Block Polish (Fine Contaminants & Heavy Metals)

The third stage uses a carbon block cartridge for final polishing — capturing any remaining fine particles, residual chemical contaminants, heavy metals including lead and copper, and cysts. Carbon block's dense structure provides longer contact time and finer filtration than GAC, making it the ideal finishing stage. For households with PFAS concerns, a high-grade carbon block in Stage 3 provides meaningful reduction of longer-chain PFAS compounds (PFOS, PFOA) from the whole-home supply.

Pressure Gauges — Know Exactly When to Change Your Filters

This system includes pressure gauges that monitor incoming and outgoing water pressure. As cartridges accumulate contaminants, the pressure differential between inlet and outlet increases — giving you a clear, objective signal that a cartridge change is due. No guessing, no unnecessary early replacement, no waiting until the filters are overloaded. It's a feature that cheaper systems don't include, and over the life of the system it saves you money and ensures your water quality never quietly degrades.

What's Included

• 3 × Big Blue 20″ × 4.5″ filter housings with 304 stainless steel enclosure & frame
• Stainless steel mounting bracket
• 3 × filter cartridges (sediment + carbon stages)
• Pressure gauges
• Housing removal wrench
• Spare O-rings

Configure for Your Water Supply

The Big Blue format accepts any standard 20″ × 4.5″ cartridge — widely available from Enviro Aqua. Configure for your water source:

• Town water with chlorine: Sediment (5µm) → GAC carbon → Carbon block
• Town water with chloramine (Sydney, Melbourne, Brisbane, Adelaide, Canberra): Sediment (5µm) → Catalytic carbon → Carbon block
• Rainwater tank: Sediment (1–5µm) → Carbon block → Sub-micron or UV stage
• PFAS concerns: Sediment → Catalytic carbon → High-grade carbon block

Not sure which configuration suits your area? Contact us and we'll recommend the right cartridge set for your water supply.

WaterMark Certification — What It Means for You

WaterMark certification (AS/NZS 3497), administered by the Australian Building Codes Board (ABCB), confirms this system has been independently tested for structural integrity under Australian mains water pressure, verified to use materials that will not leach contaminants into your drinking water, and assessed for correct fittings and pressure ratings. The manufacturing facility undergoes ongoing annual auditing as a condition of maintaining certification.

For you, this means three things: your licensed plumber can legally install this system and issue a certificate of compliance; your installation is covered under your home insurance; and if anything goes wrong, you have the backing of a certified, audited product. Verify this system on the official ABCB WaterMark Product Database.

Installation

Installed on your main cold water supply line — typically at the point where the mains enters your home, in a garage, under the house, or at the water meter. Installation must be carried out by a licensed plumber (required under Australian plumbing law for any mains connection). We recommend asking your plumber to add isolation valves and a bypass on either side of the system — this allows you to service the filters without cutting water to the whole house.

Central Coast NSW customers: we offer professional whole house filter installation by licensed plumbers on the Central Coast.

Ongoing Maintenance

Replace cartridges every 6–12 months depending on your water quality and household usage. The pressure gauges take the guesswork out of timing — a rising pressure differential tells you a cartridge change is due before water quality is affected. Big Blue 20″ × 4.5″ cartridges last considerably longer than standard 2.5″ cartridges, keeping annual running costs to approximately $120–$220 per year. Replacement cartridges are available directly from Enviro Aqua, shipped Australia-wide.