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Full Water Filter Replacement Pack for the GT1-26-4SCC 4 Stage pH Neutralising Undersink Reverse Osmosis System (GT1-11M-CC)

This Water Filter Replacement Pack suits the 4 Stage pH Neutralising 4 Stage Undersink Reverse Osmosis Water Filter System (GT1-26-4SCC).

Stage 1: 5 Micron Polyspun Sediment Cartridge (GT2-2K) (Replace Every 6 Months)

The first stage is a 5 Micron (uM) Sediment filter composed of 100% melt-blown polypropylene fibre. This cartridge helps to help protect the carbon pre-filters and reverse osmosis membrane from physical damage caused by particulate matter such as sand, dirt, silt, plant spores, and pollen. Physical contaminants such as these (which can surprisingly be found in most municipal water supplies), tend to clog up filter system components causing reduced water flow, lower osmotic pressure, diminished filtration efficiency, and ultimately, inferior water quality.


Stage 2: 5 Micron 100% Coconut Carbon Block Water Filter (GT4-7CTO) (Replace every 6 months)

The second stage is a high-grade activated coconut carbon block pre-filter. The carbon block matrix enables maximum surface area and contact time, taking the first hit to adsorb chemicals such as Chlorine (which causes damage to the membrane), along with other harmful organic chemicals and contaminants. Keeping up with regular maintenance of this pre-filter (changing it every 6 months) is crucial to protecting and extending the life of all filters that come after it.


Stage 3: 0.0001 Micron Asprinn 50 GPD Reverse Osmosis Membrane (GT36-59) (Replace every 2-4 years depending on water quality)

The RO membrane is the "engine room" of your RO system. All the crucial work is done here, so all the filters before the membrane are primarily there to protect the membrane. This membrane has a 0.0001 Micron rating and can produce up to 190 Litres (50 Gallons) of water per day.

Stage 4: Dual Finishing Cartridge: Activated Coconut Carbon/Calcium Alkalising Post-Filter (GT6-18LS) - (Replace Every 12 Months)

The last stage features a high grade of activated coconut carbon to impart a naturally sweet taste, which then passes through calcite (CaCO³) alkalising media to raise and buffer the final pH to between 7-8, without causing hardness. Note that upon installation, a new Calcium Alkalising cartridge may register an initial pH higher than 8, but it will quickly balance out.


How often should you change reverse osmosis water filters?
Filter Replacements & Maintenance Schedule

To maintain the optimum level of filtration year-round, and to ensure you get the maximum life out of your RO membrane (the engine room of this system), we strongly recommend a consistent filter maintenance schedule. 

  • Pre-Filters

    Every 6 months you will need to change the pre-filters, which help protect and extend the life of the membrane. Some people neglect to keep up with the maintenance of the pre-filters, thinking that the RO membrane will take care of it! However, the RO membrane is the most delicate and expensive filter within any RO system, so it's worth protecting your investment!

    The pre-filters thus serve the dual purpose of blocking sediment particles larger than 5 microns and removing chlorine, which both cause damage to the inside of the RO membrane in different ways:

    • Sediment particles physically damage the fine internals, causing micro-tears that allow contaminants through to the "clean" side of the osmotic membrane, as well as blocking up the membrane which can cause the system to stop producing water and force an excessive amount of water to waste. 

    • Chlorine that has been dissolved in water creates corrosive hypochlorous and hydrochloric acids, which dissolve the delicate RO membrane (via a process called "ring chlorination" which disrupts the hydrogen bonding between the membrane's polymer matrix) and allows contaminants to pass through to the "clean side". Because this process occurs gradually over time, most people don't notice the taste of contamination until they change their membrane! 

  • Reverse Osmosis Membranes*

Reverse Osmosis membranes filter down to an ultra-fine level of filtration - down to 0.0001 of a micron - which is the reason why RO membranes can filter out minerals, salts, and metals (unlike carbon). Because this level of filtration is so fine, RO membranes do eventually clog up over time. How long you will be able to get out of your RO membrane, depends on the consistency of your membrane pre-filter maintenance, along with the starting quality of your water.

Schematic diagram of the pores in a reverse osmosis membrane.

(Adapted from Geise, G.M., 2021, found in https://www.science.org/doi/10.1126/science.abe9741)

    • HARD WATER (water that is full of salts and minerals) takes a bigger toll on RO membranes than water that is SOFT (water with a low Total Dissolved Solids rating).
    • Western Australia, South Australia, the Northern Territory and Queensland tend to have hard water, along with those whose main source of water comes from a bore.

    • Thus, whilst we have specified a recommended maintenance schedule (below), the quality of the water in the area you live, is ultimately what will determine how long you get out of your RO membrane.

    • *If you are on hard water, at the 2-year mark, simply go for the FULL Replacement Pack (which includes an RO Membrane). Note - cases of extremely hard water may get less than 2 years out of an RO membrane. 

Australian Water Hardness Map Guide

  • Post-Filters

These are all filters that go after the RO membrane to buffer the pH back up from an acidic state to an alkaline state, and "perfect" the water for final consumption. Over the course of a year, the diffusion of the alkalising minerals into the water will significantly diminish, whilst the carbon post-filter will eventually exhaust its capacity to adsorb residuals. 

Please see the Recommended Filter Replacement Schedules (per the above) and links to the replacement filters:

HARD WATER - Recommended Filter Replacement Schedule*

MODERATE/SOFT WATER - Recommended Filter Replacement Schedule


Instructions for Changing your Filters at Home:

Recommended Tools Required:

  • Housing Opening Spanner (You should already have this as supplied with your system, but if not you can purchase one in the drop-down box in this listing).
  • A Shifter Wrench
  • Plumber's Thread Tape
  • A Membrane Opening Spanner (For the RO Membrane Only; you should already have this as supplied with your system, but if not you can purchase one in the drop-down box in this listing).
  • A Pair of Plyers (For the RO Membrane Only)

Before changing filters, we recommend taking a photo of the system from various angles, then one by one, changing the cartridges. This will help you remember the orientation and flow direction of the filters and will save you time as opposed to trying to put the filter back together from scratch.

  • Shutting off the water: There are 3 things you need to do in this step.

    • Firstly, locate your inlet tee valve which connects water to your system, and shut this off by turning the tap 90°.

    • Secondly, you will need to shut off the storage tank valve located on top of the storage tank.

    • Finally, to relieve pressure in the system, open the drinking water faucet tap on the sink.

  • Using Push-Fit Connections: These connections are very easy to use however if you have not used them before, they may be a little tricky at first. To remove the tubing, depress the floating collet, then pull on the tubing and it should release. When re-installing, you need to firmly push the tubing into the opening until you feel a “click” which signifies that the tubing has pushed through the internal O-ring and is seated correctly. If leaking occurs, it may be due to roughly cut tubing OR the tubing is not pushed in far enough.
  • Disconnecting the System: To make things easier, we recommend disconnecting the system and performing the filter change over the sink, rather than trying to do the filter change in a hard-to-reach place such as under the sink. We also recommend laying down some towels to mop up dripping water from the lines when you disconnect the system. The four points you need to disconnect are:

    • 1. The Storage Tank at point 12 (we recommend detaching this via the tee fitting connected to the T300 Hydrogen Rich Filter);

    • 2. The Inlet Water at point 4A (this should be disconnected at the inlet to the system ie. the elbow plugged into the Stage 1 Dirt/Sediment Filter);

    • 3. The Drain Line at point 10 (leave the Flow 200 Flow Restrictor connected to the RO membrane by the black tube in its original position), and finally;

    • 4. The Carbon Post-Filter at point 4C (disconnect tubing from the last inline carbon post-filter, which leads to the faucet tap).

      When this has been completed, you can then remove the system from under the sink and begin servicing it on the sink.

  • Changing The Pre-Filters (Stages 1 & 2): NOTE: the housings may be full of water so make sure you do this over the sink. When removing the bottom housings, you may find that they are very firmly tightened, so you may have some difficulty opening them, which is normal for water filter housings. We find the most effective way of removing the housings is to lay the system flat on its back and position the opening spanner around the housing. Using the ball of your hand, sharply and firmly hit the spanner (remember: lefty loosey) which will jolt the housing enough to break the suction seal of the O-Rings on the housing cap. Once the housing has come ajar, use the spanner or your hands to unscrew the housing completely. Remove the old cartridges and discard them (unfortunately they are not recyclable). If you would like to wash the housing out, we recommend using warm soapy water. Ensure you rinse thoroughly before re-installing the housings. If the o-rings require re-lubrication, use only a food-grade silicone-based lubricant, and only a small amount. When loading the new filter cartridges into the filter housing, unwrap them but ensure you handle the cartridges with minimal contact, especially the carbon filter (only handle these cartridges by the plastic end caps to prevent the carbon from absorbing residual odours or bacteria off your hands). When you go to do the housings back up, ensure they are in a vertical position, which will allow the filters to slot into the centre ports without damaging the inner port of the cartridges. Hand tightening is all that is required for the housings to seal correctly (see below). If you are unable to achieve a water-tight seal, you can use the opening handle to 'nip up' the last part, ensuring not to overtighten.

  • Changing the RO Membrane (Stage 3): You may wish to purchase a Membrane Opening Spanner to help with this, as membrane housings are notoriously hard to open (please note: there is no need to unscrew any of the push-fit fittings of the RO Membrane Housing)! Disconnect the tubing from the screw cap end of the membrane housing. Open the membrane housing by the end cap (as per the standard lefty loosey, righty tighty). Once you've opened the cap, pull out the RO membrane by grabbing onto the exposed stem (a pair of plyers will help with this, as it is incredibly hard to pull out the membrane with bare hands) and remove it with a pulling/wiggling/twisting motion. Discard the old membrane. Unwrap the new membrane (handle only by the stems) and push firmly to insert the new membrane into the opened housing with the o-ringed stem first, as per the below diagram. Finally, screw the RO Membrane Housing Cap back up and nip it up gently with the Membrane Opening Spanner to ensure there are no leaks, then plug in the tubing.
  • Changing the Inline Filters (Stage 4): Inline filters are very quick and simple to replace, but you will require a spanner or shifter to remove and install the fittings. Disconnect the filter from the tubing on both ends and un-clip from the mounting brackets. To replace each inline filter, use a shifter/wrench to unscrew the fitting from the filter (focus on one filter at a time), and screw the fitting into the new cartridge, before re-inserting the tubing as per the original configuration. All push-fit fittings should come with an o-ring fitted to seal the push-fit connection. If you experience any leaks or cross-threading, the fitting may require replacement (you can purchase a set of replacement fittings within this listing). Alternatively (e.g. if the o-ring has deteriorated and/or you don't have a new fitting handy), you may use 6-8 rounds of plumber's thread tape to form a water-tight seal. Once you've finished changing the inline fittings, clamp on the filter and then re-connect the tubing.

  • Re-Connecting the System: Before re-installing the system double-check over your work to ensure all fittings are installed correctly and that all tubing is correctly aligned and firmly pushed in. Re-position the system under the sink and then re-connect the tubing (inlet water, storage tank, drain line, and faucet tap). Once you have plugged the system back in, ensure all tubing is in the correct place and pushed firmly into the fittings so that they don't leak.
  • Flushing: With the faucet still open, start by turning on your inlet water only (point 1), which will force water back into the system. You will likely hear some sputtering out the faucet tap while the system purges air. During this period, inspect the filter system and check for leaks. If you find a leak, shut off the water, address the issue and turn the water back on. The water will eventually begin to flow out the tap as a slow trickle, and may notice some black water, which is normal as the filters begin to flush. Once you feel the system has purged most of the air, close the faucet tap, turn the water storage tank on (point 14), then re-open the faucet on the sink and allow all the water to run down the sink, to flush the post filters and clear excess air from the system. Once the system has "run out" of water, turn off the faucet tap, allow the system to re-fill fully (1-2 hours), and empty the tank fully. Repeat this tank flushing process again. If you still have air (which will look like cloudy water but will settle) you may need to run one more tank full of water through the system and then it will be good to go.

    If you run into any issues during this process or would like some help, do not hesitate to give us a call or email us for assistance.

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.