PSI-021-4S 4 Stage Reverse Osmosis Under Sink Unit Standard Model
- USA Made Filters
- Optional Reminerliser
- 3 Yr Warranty
Reverse Osmosis Undersink 4-Stage System
Enjoy ultra-clean water from a dedicated faucet with our efficient 4-stage reverse osmosis (RO) system. Built for reliability, it achieves a water-waste ratio of ~1.25:1 — markedly better than most standard RO units.
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 — ~200 L/day at 50 psi (350 kPa), up to ~300 L/day at 87 psi for faster refills.
- No electricity required — operates on water pressure with auto shut-off & integrated check valves.
- Low waste ratio (~1.25:1) — more water-efficient than many standard systems.
- 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 — Alkaliser with crushed marble/limestone to re-mineralise and neutralise acidity.
System Specifications & Features
- Premium components — 550 kPa pressure-limiting valve with dual check valves (WaterMark AS1357-2).
- Installation — typical install 30–60 minutes for a confident handyman.
- 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.
- ¾″ Dishwasher Adapter — use the dishwasher cold-water outlet where no dishwasher is installed.
- 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.
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 ⌀
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 — order here.
- RO membrane (about every 4 years) — order here.
- Re-mineraliser (if fitted, ~2 years) — order here.
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.