Twin Undersink Water Filter System for Rain & Tank Water (GT1-46WMAF)

This Twin Undersink Water Filter System is specifically configured to provide enhanced protection for homes using rainwater or tank water, targeting bacteria, cysts, sediment, and odour from harvested water sources.

The first stage features a 0.1 micron absolute-rated multi-stage cartridge, incorporating pleated prefiltration (10µm and 5µm), a 0.5µm carbon block, and a final hollow fibre membrane designed for ultrafine bacterial and cyst reduction. Independently tested to ASTM F838-15, this filter achieved Log8 reduction (99.999999%) of E. coli and Pseudomonas aeruginosa, while also being compliant to NSF/ANSI 42 and 53 (Cyst), FDA, and EU food-grade standards.

The second stage is a 5 micron silver-impregnated coconut carbon block, manufactured by High Performance Filtration (HPF). This cartridge improves taste, removes odours and organic residues, and incorporates silver to help discourage microbial growth within the filter itself.

Designed for easy installation under the sink, this system is compact, professionally assembled, and supplied with WaterMark certified components — making it an ideal, safe, and high-performance option for households seeking reassurance when drinking or cooking with harvested rainwater.

Filter 1: 0.1 Micron Multi-Layer Bacteria Protection Cartridge

This advanced filter combines multiple stages in a single compact cartridge: two outer pleated filtration layers (10µm and 5µm), an internal 0.5µm carbon block for chemical and taste reduction, and a final 0.1µm hollow fibre membrane for ultrafine particulate and microbial retention.

Tested to ASTM F838-15, it achieved >99.999999% (Log8) reduction of E. coli and P. aeruginosa — far exceeding typical filtration performance for household water filters. Its absolute-rated hollow fibre structure allows for dependable protection against bacteria and cysts, without compromising flow under normal kitchen pressure.

Filter 2: 5 Micron Silver-Impregnated Coconut Carbon Block (HPF)

The second stage is a high-capacity carbon block made from 100% coconut shell carbon, enhanced with silver to support internal cleanliness and help reduce odour-causing microbial activity. It effectively adsorbs residual organic compounds and improves taste — ideal for water that has been stored in tanks or passed through organic roofing materials.

This cartridge provides the final polishing stage in a rainwater system, supporting cleaner and more palatable water at the tap.

What is Silver-Impregnated (Bacteriostatic) Carbon and How Does It Work?

Silver-impregnated carbon, often referred to as "bacteriostatic", is a specially treated form of activated carbon designed to help suppress the growth of bacteria within the filter cartridge itself. While it does not kill bacteria, the presence of silver helps to maintain a cleaner internal environment by discouraging microbial colonisation.

This is particularly useful in low-chlorine or chlorine-free systems such as tank water, where untreated filters can be prone to biofilm buildup over time.

Why Choose This System Instead of UV for Undersink Use?

While UV disinfection is highly effective and remains the best whole-house solution for microbiological safety, it’s not always ideal for undersink installations. UV systems require power, consistent flow, and regular maintenance, and when installed at a single tap with low usage, they can cause issues with heat build-up inside the UV chamber.

In small UV systems, stagnant water in the chamber can become uncomfortably warm or even hot, particularly after periods of no flow — which is not ideal for drinking water and may impact taste or user comfort.

This twin filter system offers a passive, power-free alternative that physically blocks bacteria and cysts at the point of use using hollow fibre membrane technology, without the risk of heating or complexity. It's an ideal option for off-grid homes, weekenders, or any household using rainwater or untreated tank water who want targeted protection at the tap.

⚠️ Disclaimer: Do not use this system to filter microbiologically unsafe water or water of unknown quality without adequate disinfection. We recommend dosing your tank with a product such as Hydrosil Ultra 7.5% Water Sanitiser to ensure full protection against microbiological contamination in your pipework and filter system, and to help prevent biofouling within the filter.

Kit Contains

• 2 × 10" x 2.5" WaterMark Certified Filter Housings (GT8-14)

• 1 × 0.1 Micron Multi-Layer Absolute Bacteria Filter (GT42-0-MAF)

• 1 × 5 Micron Silver-Impregnated Coconut Carbon Block GT4-58BCC05

• 1 × White Powder-Coated Steel Mounting Bracket

• 1 × Modern Chrome Faucet Tap

• 1 × WaterMark Approved Pressure Limiting Valve (350 kPa)

• 1 × Leak Shut-Off Valve

• 1 × Feed Water Valve

• Tubing, Push-Fit Connectors & Housing Spanner

• Comprehensive Installation Instructions

• Optional Tap Upgrade: 3-Way Mixer Tap (charges apply)

WaterMark Certification

This system is WaterMark Certified to AS 3497:2021 under Certificate Number 23247 — the mandatory certification required for installation by a licensed plumber in Australia.

WaterMark certification guarantees the system meets Australian plumbing and safety standards. All components are compliant to NSF/ANSI 42, with the bacteria-rated cartridge also meeting NSF/ANSI 53 (Cyst) requirements and tested to international microbiological standards.

Installation Note:
Installation must be completed by a licensed plumber. Full instructions are included for a straightforward, compliant setup.