4 Stage Reverse Osmosis Under Sink Premium Model 021-4pg
  • 4 Stage Reverse Osmosis Under Sink Premium Model 021-4pg

PSI-021-4PG 4 Stage Reverse Osmosis Under Sink Premium Model 021-4pg

This Reverse Osmosis Undersink 4 Stage model PSI-021-4PG is a premium low waste 1 to 1 ratio unit configured specifically for treatment of Chloramines, Chloramines is a combination of Chlorine and Ammonia together. Optional ALKALIZER

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This is a premium system made from the finest quality parts available without compromise.

This Reverse Osmosis Undersink 4 Stage model PSI-021-4PG is a premium low waste 1 to 1 ratio unit configured specifically for treatment of Chloramines, Chloramines is a combination of Chlorine and Ammonia together.

A normal Reverse Osmosis or Filter system containing coal or coconut carbons will treat the chlorine component but will leave the ammonia component, this system will remove both, Brisbane and Sydney water is treated with chloramine.

Optional with in-line re-mineraliser (ALKALIZER) making it a 5 stage extra $30.00


See faucet (tap) range, click here to view.



Supplied with QMP-300-HP U.S.A. made housing 10" Australian Standards AS3497 with 1/4" NPT threaded ports. This housing is tough with a burst strength of 575psi (4000kpa) and is tested to AS3497 which means it has been tested from 0 to 700kpa and back to 0 kpa 100,000 times without failure, cracking or distortion.

With these premium systems we supply the 550kpa pressure limiting valve with dual check valves which is a plumbing code requirement, the valve is also Watermark AS1357-2 licence no 23133 as the watermark is also a plumbing code requirement.

We supply the 550kpa PLV with the premium system so the filter system runs faster than other units on the market.

Click here to down load a sample of the installation instructions pdf format

Features the exclusive membrane flushing.

It has the Dow Filmtec 300 litre per day TFC membrane, the 300 litres is rated at 50 psi (350 kpa) but will produce up to 450 litres per day higher pressures, what this means is the system will fill faster than most systems on the market. This system has an auto shut-off device that closes off the in-feed supply when the storage tank has filled.

All components are NSF certified to standards 042, 053 & 058

Mains connect systems click here to view how each are installed water filter parts

Highest Quality QMP-300 US housings, standard size 10 inch (9 ¾" (248mm) NSF certified (worlds leading certification authority) NSF/ANSI standard 042 certification, also tested and certified to Australian Standards 3497

Removes 96-98% of Fluoride

For membrane treatment rates click here.

Click here to jump to the re-order for the correct annual stages 1 & 2 cartridges.

Click here to jump to the re-order for the correct annual stage 4 cartridge.

Click here to jump to the re-order for the correct membrane changed usually at the 4th year.

If your system has the in-line re-mineraliser/alkaliser fitted click here for that replacement cartridge, normally changed every second year.

1 Micron food grade polyspun sediment filter 9 ¾" (248mm) (standard size) U.S. made

Matrikx CTO chloramine carbon cartridge

Genuine Omnipure CL10RO- Coconut carbon post filter, highest quality possible. U.S. made

Genuine Dow Filmtec TFC Membrane (standard by which all other membranes are measured)

This unit comes with a mounted pressure gauge to indicate when the pre-filters are starting to block with sediment rubbish in the water mains. Main filter unit size, 42 cm high, 35 cm wide & 14 cm deep.

9 litre stainless steel storage tank (exceeds drinking water guidelines) NSF Certified. If space is an issue we also offer a 4.2 litre or 12 litre tank

Click here for tank details.

Premium systems now have the lowest waste ratio of all systems on the Australian market, using a Patented combination membrane flushing valve/flow restrictor means the waste ratio is about 50% less waste than other brands, waste ratio is now about 1 to 1.

Installation choice 1/2" tee olive fitting, 3/4"dishwasher adapter or 1/2" easy fit braided line flick mixer adapter, our systems take the average handyman 1/2 to 1 hour to install.

600 kpa pressure-limiting valve, genuine QMP Stainless Steel dedicated faucet. Housing spanner to ease cartridge changes.

10 year warranty

Click here for selection Advice

PSI Systems are Better Than Other Brands, click here to find out why

All reverse osmosis systems require a minimum pressure of 40 psi (280kpa) with 50 psi (350kpa) or more is ideal. If you are unsure what your pressure is check with your local Council or water authority.

Product comes complete, ready for installation.


Substance treatment rates below for TFC reverse osmosis, click here for a full list in PDF.


The model PSI-021-4PG is a 4 stage undersink reverse osmosis unit designed to treat water from the mains supply that has been treated with chloramines.


A normal reverse osmosis system will not treat the ammonia component of chloramine which is a combination of chlorine and ammonia together. The reason the ammonia cannot be treated with a normal non chloramine system is the ammonia is in a gas form and not a liquid and as a result will pass through the membrane. A normal (non chloramine) system will treat the chlorine component of chloramine but will liberate the ammonia which will pass through the system and remain in the product water.


The carbon pre-filter in a chloramine system such as the PSI-021-4PG is what is called catalytic carbon which results in the successful treatment of the chloramine while the chlorine and the ammonia are still chemically bonded.


There are 2 levels of chloramine carbon, catalytic carbon and enhanced carbon with the catalytic carbon being the superior of the two when it comes to treatment of chloramines. Both are coconut based carbons but both are treated in a special way which remains a secret by the manufactures with the catalytic being the most difficult to manufacture and that is reflected in the higher cartridge cost. In this system we use the Pentek ChlorPlus-10 chloramine catalytic carbon cartridge and can be viewed at this replacement cartridge page link.


This model is one of our premium range which is second to nothing on the market when it comes to reliablity which will result in faultless years of operation if maintained correctly.


Chloramine systems such as this model will cost on average $20.00 per year more to run than the non chloramine systems which is good value when you think about drinking low doses of ammonia.


Chloramine systems such as this one will not treat the ammonia if there is a whole house system installed which has a carbon based cartridge which is not catalytic carbon because once the chlorine and ammonia are split and no longer chemically bonded the catalytic carbon cannot treat ammonia on its own. If you have a whole house system then it is that unit which should have the chloramine (catalytic) carbon in it and the reverse osmosis system only needs to be a normal type. The reason for this is the first carbon of contact the water makes from the mains supply needs to be chloramine carbon system.


Sydney and Brisbane water is treated with chloramines but there are also some smaller regional areas that are also treated with chloramines and it is hard for us to keep track of all treatment plants around the country so if you are not sure we suggest you contact your local water authority and ask them as you have that right. If you purchased a chloramine system such as this one it will perform brilliantly with chlorine only water and if you found out later that the water was for sure only treated with chlorine you can drop back to a normal carbon pre-filter saving a few dollars.


Product Details

Data sheet

10 Years Warranty
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