Reverse Osmosis Undersink 4-Stage System – Premium Water Filtration
Now proven to reduce PFAS (including PFOA) up to 99.9% when properly maintained.
Enjoy ultra-pure water directly from your dedicated faucet with the premium PSI-021-4P reverse osmosis system. Reverse osmosis is widely recognised as the most effective and dependable way to filter drinking water, removing chlorine, heavy metals, fluoride, hardness, salts, and a wide range of dissolved substances for clean, great-tasting water.
Designed for efficiency and reliability, it features a genuine Dow FilmTec 300 L/day membrane and an improved ~1:1 waste ratio for excellent water economy.
Why Choose This System?
- Compact under-sink installation — neat footprint with a dedicated faucet for easy access.
- Advanced 4-stage filtration — high-performance, U.S.-made filters for excellent taste and clarity.
- Genuine DOW FilmTec membrane — ~300 L/day at 50 psi (350 kPa) for faster refills.
- Low waste ratio (~1:1) — advanced flushing for better water efficiency than standard systems.
- Auto shut-off — automatically stops water flow when the storage tank is full.
- Certified & compliant — components to Australian Standards + NSF/ANSI 42/53/58.
- Optional alkaliser — restores minerals and balances pH for smoother taste.
How It Works: 4-Stage Filtration
- Stage 1 — 1 micron sediment (U.S.) removes dirt, sand and particulates.
- Stage 2 — Omnipure coconut carbon block (U.S.) reduces chlorine, chemicals and odours (rated ~37,000 L chlorine removal).
- Stage 3 — DOW FilmTec RO membrane (U.S.) removes ~96–98% fluoride, heavy metals and dissolved impurities (TFC).
- Stage 4 — Omnipure coconut carbon post-filter (U.S.) polishes taste and removes residual organics.
- Optional — Remineraliser with crushed marble/limestone to re-mineralise and neutralise acidity.
PFAS Reduction & Water Quality
This system uses a carbon pre-filter, a high-rejection membrane, and a final carbon polish — a combination shown to effectively reduce a wide range of contaminants, including PFAS (such as PFOA), for safer everyday drinking and cooking.
Most town supplies in Australia sit around pH 7–7.5 (slightly alkaline). After the membrane stage, minerals are very low and pH naturally drops to ~pH 6 (slightly acidic). Long-term consumption of water below pH 7 isn’t recommended unless advised by a health professional.
To balance this, purified water is stored in the tank and passes through the remineraliser (if fitted) and carbon cartridge before dispensing, lifting pH back above 7 for smoother, better-balanced drinking water.
System Specifications & Features
- Premium components — QMP-300-HP housings; burst strength ~575 psi (≈4000 kPa); NSF/AS compliance.
- Installation — typical install 30–60 minutes for a confident DIYer/tradesperson.
- Minimum pressure — 40 psi (280 kPa); ideal: ≥50 psi (350 kPa).
- Main unit size — 42 cm (H) × 35 cm (W) × 14 cm (D).
Connection Types
- ½″ Flick-Mixer Braided Line — most common in modern kitchens. Fit the supplied adapter with the rubber washer, then re-attach the braided hose to the adapter’s ½″ male thread. Details/Instructions
- ¾″ Dishwasher Adapter — use the dishwasher cold-water outlet where no dishwasher is installed. Details/Instructions
- ½″ Tee Olive Fitting (Copper) — typical for older homes with copper pipes to separate taps. Cut 45–50 mm from the ½″ copper line, deburr, install the tee, then proceed with the standard PLV/tubing steps. Details/Instructions
Storage Tank Options
- Standard — 9 L stainless steel tank (NSF certified).
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Alternative sizes:
- 4.2 L — 33 cm (H) × 20.5 cm ⌀
- 9 L — 39 cm (H) × 24 cm ⌀
- 12 L — 39 cm (H) × 27.5 cm ⌀
- DATA SHEET
Faucet Options
Bundle & save: upgrading your faucet with the system is cheaper than buying it later.
Browse Faucet Range, then select your choice from the Faucet Option dropdown above.
Replacement Cartridges & Maintenance
- Annual cartridge pack (ROCDU-02) — order here.
- RO membrane (~4 years) — order here.
- Re-mineraliser (if fitted) (~2 years) — order here.
Performance Data
The system demonstrates high contaminant removal rates across both inorganic and organic compounds:
Inorganic
- Aluminum 99%
- Arsenic 98%
- Arlum 95%
- Cadmium 95%
- Calcium 98%
- Chromium III 98%
- Copper 90%
- Fluoride 98%
- Iron 98%
- Lead 90%
- Magnesium 98%
- Manganese 90%
- Mercury II 85%
- Nitrate 90%
- Potassium 95%
- Selenium 95%
- Silver 98%
- Sodium 95%
- Strontium 90%
- Sulfate 90%
- Zinc 98%
- Total Dissolved Solids 95%
- Asbestos 99%
Organic
- Chlorine 98%+
- Herbicides 98%+
- Pesticides 98%+
- DDT 98%+
- Endrin 90%+
- Lindane 98%+
- Aldrin 98%+
- Benzene 98%+
- VOCs 98%+
- Atrazine 98%+
- Fluoranthene 98%+
- Phenol 98%+
- Trihalomethanes 98%+
- Toxaphene 98%+
- Dichloromethane 98%+
- Chloroform 98%+
- Trichloroethylene 98%+
- Perchloroethylene 98%+
- Tannic Acid 98%+
- Methoxychlor 98%+
- PCB 98%+
Performance Data Sheets
- Membrane — DATA SHEET
- Sediment — DATA SHEET
- Pre Carbon — DATA SHEET
- Post Carbon — DATA SHEET
Warranty
This system is backed by a 5-year warranty for peace of mind. Built with premium components and tested for durability and performance. Covers defects in materials and workmanship under normal use — see full warranty terms for details.