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.

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

Replacement trio cartridge pack (annual change) are offered at 20% discount when ordered with the filter unit, normally $80.00 per set of 3 but offered for $64.00

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 Filtermate 600kpa pressure limiting valve with dual check valves which is a plumbing code requirement, the valve is also Watermark AS1357-2 licence no 02596 as the watermark is also a plumbing code requirement.

We supply the 600kpa 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.

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

Pentek ChlorPlus-10 Chloramine carbon cartridge 13000 litres rating, U.S. made

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. click here to obtain more information about waste ratios

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 Tomlinson Stainless Steel dedicated faucet. Housing spanner to ease cartridge changes. Replacement set of cartridges.(3) $80.00, less 20% if a replacement set is ordered with the unit.

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.