Reverse Osmosis Undersink 4-Stage System with Gauges & Monitoring – Premium Water Filtration

The PSI-021-4GM is one of our premium 4-stage reverse osmosis systems, designed with advanced monitoring tools and industry-leading components. It delivers clean, healthy drinking water and gives you full visibility into how your system is performing. This model includes dual stainless steel pressure gauges, a built-in TDS (Total Dissolved Solids) monitor, and an onboard membrane flushing valve for easy maintenance.

Advanced Features for Peace of Mind

• Dual Pressure Gauges – One gauge measures mains water pressure, which can vary throughout the day, while the second gauge measures the pressure after the two pre-filters and before the membrane. The difference between the two gives a clear indication of pressure drop caused by sediment or dirt clogging the pre-filters. This acts as a diagnostic tool—if your system’s flow rate drops, the gauges help pinpoint the cause quickly.
• Hand Held TDS Meter – Monitors the amount of dissolved solids before and after the membrane. TDS levels in mains water vary—often highest in summer—so being able to check the difference between in-feed and product water ensures your system is operating correctly and your water is pure.
• Onboard Membrane Flushing Valve – Makes it easy to flush the system and extend membrane life by clearing out any deposits such as calcium or salts. Helps maintain optimal performance and high purity levels.

What Sets This System Apart?

This system is part of our premium range, hand-built using the best quality components sourced from around the world. While many aspects of quality may not be obvious to the untrained eye, here’s what makes this system exceptional:

• Pressure Gauges – Stainless steel, oil-filled, pressure-compensating gauges — the best available in the industry.
• Housings – U.S.-made QMP housings, burst pressure rated to 575 psi (4000 kPa) — virtually bulletproof.
• NSF-Certified Tubing – British-made John Guest tubing, NSF Standard 61 compliant and pressure rated to 230 psi (1600 kPa).
• Auto Shut-Off Valve – Made in the USA by Hydromatic for long-term reliability.
• Check Valve – Stainless steel, U.S.-made for maximum backflow protection.
• Fittings – Only genuine John Guest and Jaco Gripper Series fittings are used—no cheap substitutes.
• Faucet – Italian, USA or Taiwan-made dedicated tap, all NSF certified lead-free. While most suppliers use non-NSF taps that may contain 6–11% lead, we only use certified safe models.
• Membrane – Genuine USA-made Dow Filmtec membrane with serial number and hologram for authentication — no Chinese copies here.
• Filters – All U.S.-made and tested to Australian Standard AS3497 for safety and performance.
• Inlet Ball Valve – WaterMark certified to Australian Standards — unlike most suppliers who skip this critical detail.

4-Stage Filtration Process

• Stage 1: 1-Micron Sediment Filter – U.S. made food-grade filter removes dirt, sand, and suspended particles.
• Stage 2: Coconut Carbon Block Filter – Omnipure U.S.-made filter reduces chlorine, organic chemicals, and bad taste (37,000L chlorine rating).
• Stage 3: Dow Filmtec Reverse Osmosis Membrane – Removes 96–98% of fluoride, salts, nitrates, heavy metals, and more.
• Stage 4: Coconut Carbon Post Filter – Final polish filter enhances taste and removes any remaining VOCs.
• Optional Stage: Alkaliser (Re-Mineraliser) – Adds healthy minerals and balances pH for those who prefer alkaline water.

System Specs

• Minimum Operating Pressure – 40 psi (280 kPa), optimal performance at 50 psi (350 kPa).
• Main Filter Unit Dimensions – 42 cm high × 35 cm wide × 14 cm deep.
• Includes Dedicated Drinking Tap – Stylish and lead-free, with several finish options available.

Storage Tank Options

• Standard Tank: 9L stainless steel tank (NSF certified, meets all Australian drinking water standards).
• Optional Tank Sizes:
  • 4.2L: 33 cm high × 20.5 cm diameter
  • 9L: 39 cm high × 24 cm diameter
  • 12L: 39 cm high × 27.5 cm diameter

Cartridge Replacements

• Annual Filter Pack (ROCDU-02) – Click here to order.
• RO Membrane – Replace every 4 years. Click here to order.
• Re-Mineraliser Cartridge – If fitted, replace every 2 years. Click here to order.

Warranty

Backed by a 5-year warranty, this system is made using only high-grade, internationally recognised components. Every part has been selected for reliability, safety, and performance. From the membrane to the fittings, you’ll get a system that not only delivers excellent water but is built to last.