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Twin Undersink High Flow Mixer Tap Compatible Water Filter System (GT1-3MK)

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Quick Overview
  • Perfect for Treating Chlorine on Mains/Town Water
  • High Flow Design can be Plumbed Directly into the Cold Water Line on your Existing Tap
  • Double Carbon for Excellent Chlorine Reduction & Longer Filter Life
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Twin Undersink High Flow Mixer Tap Compatible Water Filter System (GT1-3MK)

For maximum flow with double carbon filtration.

This kit offers full flow to the cold water outlet on your original mixer tap.

This eliminates the need for a separate drinking water faucet on the sink.

Because this system is 1/2" straight through there is no need to drill a hole in your sink, or through a granite bench top to install a separate faucet. This system gives you the convenience of just one tap on the sink with great-tasting filtered water straight from the cold water line in your current tap.

Complete with two meters of 3/8" tubing (which has the same internal diameter as 1/2" copper tubing), so full flow can be maximized. Provided you have a mixer tap with flexible lines attached, you will be able to install this kit quickly and easily, without any cutting or drilling.

Supplied in the kit are two fittings to suit the 3/8" tubing - one with a female 1/2" BSP thread and the other with a male 1/2" BSP thread - so installation is a simple matter of interrupting the cold water line from the supply to the flexible line on the mixer tap.
Having said this, most flexible mixer hoses are 1/2" - but double-check this before ordering.
Because of the extra flow rate this system generates, we use two carbon filters for double the contact time, the first being a 1 Micron Coconut Carbon Cartridge, and the second, a 0.5 Micron Premium Coconut Carbon Cartridge for an excellent reduction in Chlorine. This particular combination of filters, therefore, offers a full flow rate resulting in chemical-free great-tasting water.

This system also contains a high-quality Apex (Watermarked) Pressure Limiting Valve (PLV). These are a must-have when dealing with water filtration on mains water. The PLV will help protect your filter system from rises in pressure which is a very common occurrence. NOTE: A PLV will not protect a filter system from water hammer. If you know you have a water hammer issue or you are unsure, please install a hammer arrestor, or contact us prior to purchase.
Depending on your available pressure, it is possible that you may experience a reduced flow rate when using double carbon filtering. If this does occur, this is quite normal, however, the reduction is not significant nor likely to be a problem unless you know that your water pressure is less than 40 PSI. The average town supply is generally around 50 - 80 PSI.

INSTALLATION - Please note this system is WaterMark Certified to Australian plumbing standards (AS/NZS 3497), and will need to be installed by a licensed plumber. Simply order online with free shipping to your home, and once it arrives any local licensed plumber will be able to do the installation (the system also comes with instructions)!

MAINTENENCE - Please see below the Recommended Filter Replacement Schedule and link to the replacement filters for this System:

Every 6 Months - Replacement Water Filter Cartridges Dual Coconut Carbon Block | 10" X 2.5" (GT4-6CTO + GT4-4CTOP)

A Note on Chloramine: 

Please note that the flow rate on this system is too fast to enable any significant reduction of Chloramine from tap water. If Chloramine is your concern, check out our Maximum Chemical Reduction Twin Undersink Chloramine Filter for Mains Water | Watermark Certified (GT1-46WM) - pictured below:


Height: 358mm
Width: 240mm
Depth: 125mm

Return Policy

Due to the nature of the products we sell, a strict return policy is in place. We work with food grade certified materials that must be un-opened and un-used as to be able to be re-sold.

You may receive a refund or credit of equal amount, less the restocking fee if applicable and any other deductions that are relevant.

  • Wrongly purchased items may be returned for a merchandise credit, this applies for but not limited to: Wrong size, wrong system etc.
  • 30 Day return Policy: Returns will not be accepted without prior approval or after 30 days of invoice date.
  • All returns will incur a 17.5% restocking fee or cost to send the item to you whichever greater. FSA may use discretion to determine the restocking fee.
  • Any damages (minor, that can be repaired) will incur a fee which will be deducted from the total refund which will be equal to the cost of the replacement
    parts (List Price) and labour charge (if applicable) to repair the system(s). This will be separate to the restocking fee.
  • Any damage considered to be major and not feasible for repair may be refused and the return request will be void. The customer will be responsible for the return freight or disposal of the damaged unit.
  • Return shipping is to be paid by the buyer to the address provided. It is recommended that the customer applies transit warranty to the return freight in case of damage.
  • Any damages to the system that were not reported to FSA within 48 business hours of receipted delivery are not covered under our transit warranty.

  • Should the item appear faulty or doesn’t work how described, the unit/item must be returned for testing (if requested), the return postage paid by the buyer. If the unit/item is deemed to be faulty, compensation will be provided for the postage cost (Proof of cost required). If the unit/item is deemed to be in working order and as described, the buyer will responsible for return postage.

If you have any questions about our return policy, please contact us before purchase. This will also help to ensure you purchase the correct product that suits your requirements.

Can I install my Water Filter on my own or do I need a Plumber?
For quality assurance and Insurance reasons, we always recommend using a licenced plumber who is familiar with water filtration. This ensures that the installation runs smoothly and is professional. If you fancy yourself reasonable at DIY type projects, we provide you with all the necessary components and instructions you need to conduct the installation yourself. Our technical support team are contactable during business hours on 1300 888 008 should you have any queries about installation.

Will Undersink Water Filters Remove Fluoride?
Standard Undersink filters will not remove fluoride from the water, we recommend using reverse osmosis as it is the safest, and most effective way of removing Fluoride from the water. There are proclaimed Fluoride Removal Cartridges on the market however they use a material called Activated Alumina which will remove Fluoride up to approx. 80% while the filter is new, but will then rapidly depreciate to the point where it is no longer effective. The other down side to the Activated Alumina cartridges is, they have a tendency to leach heavy metals into the water when the filter ages. If you do not keep a strict routine for filter replacement, it may be introducing dangerous heavy metals into your drinking water.

What are Undersink filters for?
There are a few different models of Undersink filter that each have their own specific purpose. The most common model of Undersink filter you will come across is a Sediment + Coconut Carbon configuration. As the name suggests, they have a dual action, the first filter will remove dirt/particles and sediment, while the Coconut Carbon filter absorbs chemicals from the water such as Chlorine.
Some systems elect to use a Dual Coconut Carbon Set up to double the contact time with the water. As we know that carbon efficiency is majorly to do with Contact Time adding more carbon to a system can greatly increase its ability to remove hazardous chemicals, Tannins, Tastes and odours.

Can an Undersink Water Filter remove Chloramine?
Chloramine Injection has recently been introduced into many council regions over Australia, including on the Gold Coast where FSA is based. Chloramine presents a number of issues in regards to drinking water including but not limited to; dissolving of heavy metals such as lead into the water, release of ammonia gas and adverse skin reactions. As previously mentioned, the more carbon the better. Chloramine is very hard to remove by normal means and it is removed in 2 staged. The first carbon filter acts to break open the Chloramine which in turn, releases the other various residual gasses into the water, the second carbon can then easily extract and absorb all remaining residuals, effectively removing the dangerous Chloramine from your drinking water.

How often should I change the filter cartridges?
Undersink Water Filter Cartridges should be changed anywhere between 6-12 months. You will usually notice a distinct change in taste of the water if you have the filters in too long. This signifies that the Coconut Carbon Cartridge is no longer working to its full capacity and is beginning to allow residual amounts of chemicals through into your drinking water. As a rule, you should not leave your filters in for longer than 12 months regardless if you are on town OR rain water.

What is filter protection equipment, and do I need to use it?
 Filter Protection Equipment is an important part of water filtration. Our products are sourced from experienced and reliable manufacturers and also carry the highest level of certification in the water filtration industry. Regardless of Brand, Make, Model or Country of manufacture, water filtration will ALWAYS be the weakest point in your plumbing. The three main causes of water filtration failure are; Overnight pressure surges, Intense Water Hammer Pressure Impacts, and thermal expansion. All of which can be addressed and prevented with a few simple pieces of equipment. A Pressure Limiting Valve is used to buffer the incoming pressure to the Australian Regulation Pressure of 500kPA. This is the minimum requirement for most insurance and warranty validation and is essential when used on Town mains / municipal water. A Water Hammer Arrestor is a copper tube looking device which is commonly found in the laundry (If you have one). It acts to absorb and dissipate pressure spikes in your water lines. Pressure spikes occur from appliances such as the washing machine or dishwasher and can magnify the water pressure tenfold which can cause serious damage to water filtration components. Water hammer gets the name by the distinct sound you hear when the shockwaves rattle loose copper pipes or worn out valves. This is something that is essential to be addressed immediately before installing water filtration. A Pressure Relief Valve is as it sounds. It is pre-set to open once the pressure reaches 110PSI, shooting that pressure/water down the drain line and easing the pressure in your water filter. This is a requirement if you intend to hook up your water filter to a fridge, chiller or ice maker. They are also a good idea to help relieve residual pressure from pressure surges (even if you have a PLV + water hammer arrestor).