PSI-021-4S 4 Stage Reverse Osmosis Under Sink Unit Standard Model





Regular price $510.00
Regular price $510.00
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4 Stage reverse osmosis system, filmtec membrane, omnipure carbon and post filters.

200 litre per day genuine Dow Filmtec membrane @50 psi, 300 litres @ 87 psi. LOW WASTE 1.25 to 1. All components are Australian Standards and or NSF certified. Optional ALKALIZER


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


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

It has the Dow Filmtec 200 litre per day TFC membrane, the 200 litres is rated at 50 psi (350 kpa) but will produce up to 300 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 or 058


Removes 96 to 98% of Fluoride, for membrane treatment rates click here.

Click here to jump to the re-order for the correct annual trio pack of cartridges.
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

Omnipure OMB934-5M coconut quality carbon cartridge 9 ¾" (248mm) 37,000 litres chlorine rating, U.S. made

Genuine Omnipure CL10RO-T33 Coconut carbon post filter, highest quality possible. U.S. made

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

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.

4.2L - 33cm high and 20.5cm diameter

9L - 39cm high and 24cm diameter

12L- 39cm high and 27.5cm diameter

Standard type flow restrictor

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

Mains connect systems click here to view how each are installed

This Reverse Osmosis system was originally developed to compete directly with the Chinese imported systems.

At first we tried the same components as they use but with better Taiwanese housings and American cartridges, but some of the components during testing failed.

First we up-graded the auto shut off valve to the U.S.A. made Hydromatic valve which has proved to be very reliable as well as the Hydromatic check valve, we then found the Chinese copy of the Jaco fittings to also be of poor quality and subject to blow off so we up-graded them to the genuine Jaco gripper series which never let go, then it was the tubing that we up-graded to the genuine British John Guest tubing which is extremely high quality, next was the Faucet, we purchased some of the non NSF faucets to supply with the system but with between 6 to 11% lead content in the brass the faucet was made from the water had a metallic taste when first used after sitting say overnight so we tossed those faucets in the garbage and purchased NSF no lead faucets to supply with the systems, so in the end we found that we had a system that was reliable but costs more to produce than the Chinese systems.

The PSI-021-4S may not be as cheap as the Chinese systems but we could not sell a system that would have been a problem for our customers as well as being a warranty nightmare for us.

In the end the PSI-021-4S Undersink reverse osmosis system is good quality, is reliable, suits those looking for a budget system without running the risk of buying a system that will give them problems, the price doesn’t match the Chinese systems but we would rather miss a sale than sell something that would fail. product comes complete, ready for installation.

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.

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

If you choose to have the TDS meter with the unit beware that the system will have an elevated reading due to having the reminerliser cartridge.

Customer Reviews

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Customer Reviews

Based on 4 reviews
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vicki cashion

Beautiful sweet water from the tap 😃 I used to spend so much on boxed water. This is awesome and essential if clean water is up there as one of your priorities

F
Fiona Grant
Water with no aftertaste

Loving my new water filter, the water has no aftertaste and I find I’m drinking more water which is great. Service was great, so helpful and arrived quickly

J
Janice Voon
Quality, value, pre-built

I think this could the best quality vs price out there in Australia. Thank you for providing this service / these products

M
Martina Sackmann

Best water filters ever! Have been buying from PSI water filters for over 15 years. Everyone in my family now has one.