tankRo RO132-TNK RO Water Filtration Expansion Tank - Compact 4 Gal

In this review the tankRo RO132-TNK expansion tank is evaluated as a replacement or upgrade for under-sink reverse osmosis systems. The bottom line: it is a compact, NSF certified storage tank that delivers clean, neutral-tasting water and fits under most kitchen sinks, making it a practical choice for homeowners who need an easy-to-install RO storage solution. The single biggest reason to buy is the combination of a post-cured diaphragm for sterile water delivery and a durable steel shell that supports reliable day-to-day use.

Key Features

• NSF Certified: The tank and all components are certified for safety so users get contaminant-free storage for drinking water.
• Compact Size: With dimensions of about 15 x 12 x 12 in the tank is designed to fit under most kitchen sinks and in tight cabinets.
• Effective Capacity: The reservoir holds up to 3.2 gallons of water on demand while the pre-pressurized air bladder helps maintain steady flow.
• Durable Construction: Deep-drawn steel domes and precision welding provide long lasting value and resistance to everyday wear.
• Included Accessories: The tank ships with a tank ball valve and tank stand for straightforward replacement or initial installation using quick-connect fittings.
• Weather Resistant Finish: A two-part epoxy primer and polyurethane coating improve durability for indoor or protected outdoor use.

Who It's For

This tank is best for homeowners and renters who already have a reverse osmosis system and need a compact, reliable storage tank that fits under a sink. It appeals to people who prioritize certified components and sterile water delivery for drinking and cooking.

It is less suitable for those who need very high pressure delivery out of the box or who require a larger than 4 gallon capacity; professionals installing whole-house systems should look for larger commercial tanks or dedicated pressure boosting solutions.

Pros & Cons

Pros

• Works well as a replacement tank and is reported to be simple to install with the included ball valve and quick-connect design.
• Quality feel and construction, with customers praising value for money and durable materials.
• Compact footprint fits under most sinks while still supplying around 3.2 gallons of usable water.
• All components are NSF certified, adding confidence in water safety.

Cons

• Some users report mixed experiences with water pressure, so results depend on the rest of the RO system and plumbing.

Specifications

Brand	EXPRESS WATER
Model	tankRo RO132-TNK
Capacity (tank reservoir)	3.2 gallons usable
Overall tank capacity	4 gallon (4 Gal nominal)
Dimensions	15 x 12 x 12 in
Maximum working pressure	100 PSI
Included accessories	Tank ball valve and tank stand

Our Verdict

The tankRo RO132-TNK is a practical, well-built RO storage tank for most under-sink systems; it pairs certified sterile water delivery with compact dimensions and useful accessories. For anyone replacing a household RO tank or adding a compact storage vessel, it offers solid value, though those wanting stronger outlet pressure or larger capacity should evaluate system-wide options.

Frequently Asked Questions

Will this tank fit under most kitchen sinks?
Yes, the compact 15 x 12 x 12 in footprint is designed to fit under most sinks and cabinets.

How much usable water does the tank hold?
The reservoir delivers about 3.2 gallons of usable filtered water; the remaining space contains the pre-pressurized air bladder.

Does it include a valve or stand?
Yes, the tank ships with a free tank ball valve and a tank stand for easier installation and replacement.