Description
A complete RO storage tank kit — pressurized 4.5-gallon steel tank with food-grade bladder, a tank stand for stability, and a 1/4″ ball valve for shut-off. Everything you need to add or replace a storage tank on an under-sink reverse osmosis system.
What it is
This is a pressurized RO storage tank designed for under-sink reverse osmosis systems. The tank stores purified water under air pressure so you get instant flow at the faucet — even though the RO membrane produces water slowly, the tank delivers it on demand when you turn the tap.
It ships as a ready-to-install kit with the tank, a matching stand (keeps the tank upright and off the cabinet floor), and a 1/4″ ball valve that threads onto the tank’s top connection for easy shut-off during filter changes or maintenance. Manufactured by TankPAC / Globalwater (model RO-132), CE marked.
What’s included
- ✓4.5-gallon pressurized RO storage tank (holds approx 3.2 Gallons)— steel shell, food-grade internal bladder, white powder-coated finish
- ✓Tank stand — keeps the tank upright and stable under the sink
- ✓1/4″ ball tank valve — threads onto the tank’s top port for easy shut-off (1/4″ FPT × 1/4″ QC)
Key benefits
- ✓Instant water on demand — the tank stores RO water under pressure so you don’t wait for the membrane to produce
- ✓Complete kit — tank + stand + valve in one purchase, ready to install
- ✓Food-grade bladder — keeps stored water separate from the air charge (no air/water mixing)
- ✓Standard 1/4″ connection — fits virtually all residential under-sink RO systems
- ✓Ball valve included — shut off the tank during filter changes without disconnecting tubing
- ✓Steel construction — durable, powder-coated white finish fits under any cabinet
How it works
The tank uses a pressurized bladder system. The air side (pre-charged to ~7 PSI) pushes against the water side of the bladder. As the RO membrane produces purified water, it fills the bladder and compresses the air. When you open the faucet, the compressed air pushes the stored water out — delivering instant flow.
The auto shut-off valve in your RO system senses when the tank is full (back-pressure equals line pressure) and stops the membrane from producing. When you draw water and pressure drops, the membrane starts again automatically.
Specifications
Installation
- Place the tank on the included stand under the sink, near the RO system.
- Thread the ball valve onto the tank’s top 1/4″ port (hand-tight + 1/4 turn with a wrench; use PTFE tape).
- Connect 1/4″ tubing from the RO system’s tee fitting to the ball valve’s quick-connect port.
- Open the ball valve and let the system fill the tank (first fill may take 2–4 hours depending on membrane GPD and water pressure).
- Discard the first full tank of water to flush the system and any residual taste from the new bladder.
- Check air pre-charge with a standard air-pressure gauge on the bottom Schrader valve (should be 5–7 PSI with the tank empty). Adjust with a bicycle pump if needed.
If water flow from the faucet becomes weak even though the tank feels heavy (full of water), the air pre-charge may have dropped. Close the ball valve, drain the tank through the faucet until empty, then re-pressurize the air side to 5–7 PSI through the bottom Schrader valve with a bicycle pump. This restores the “push” that delivers water to the faucet.



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