Reverse Osmosis Water Storage Tanks

Pressurized Diaphragm Tanks

Standard residential reverse osmosis systems use hydropneumatic pressure tanks with a flexible diaphragm that separates purified water from compressed air. When the faucet opens, air pressure pushes stored water through the system without requiring external power, providing consistent water pressure while the RO membrane continues producing water. Common tank sizes range from 2 to 40 gallons, with usable capacity varying by model and air pre-charge.

Steel, Stainless Steel & Composite Tanks

Powder-coated steel tanks are commonly installed beneath kitchen sinks, while stainless steel models are preferred for high-purity applications. Fiberglass-reinforced composite tanks offer excellent corrosion resistance in demanding environments. Many RO tanks feature food-grade diaphragms or polypropylene liners, and select models are certified to NSF/ANSI 58 standards.

High-Capacity Commercial Tanks

Commercial reverse osmosis storage tanks help bridge the gap between membrane production and peak water demand. Restaurants, cafés, breweries, laboratories, and industrial facilities rely on larger pressurized tanks to reduce system cycling and maintain consistent flow. Atmospheric storage tanks provide even greater capacity but require a separate delivery pump.

Start by determining your daily water usage, peak demand, and required usable capacity. Keep in mind that the listed tank volume represents total internal capacity, while the actual amount of stored water depends on feed pressure and air pre-charge. For example, a typical 4.5-gallon residential tank measures approximately 11 inches in diameter and is rated for pressures up to 100 psi, while a 14-gallon model is roughly 15 inches wide and 23 inches tall.

Verify the tank's maximum working pressure, construction materials, certifications, and connection size before purchasing. Match the inlet threads and shutoff valve with your system's tubing, including 1/4-inch or 3/8-inch quick-connect fittings when applicable. Measure your installation space carefully and leave enough clearance to access the valve. For commercial systems, compare tank drawdown with membrane production rates, peak demand, and operating pressure requirements.

Before installation, shut off the water supply and relieve system pressure. Check the tank's air pre-charge only when the tank is completely empty. Most residential tanks are set between 5 and 7 psi, but always follow the manufacturer's recommended specifications.

After connecting the tank valve and tubing, restore the water supply and inspect all fittings for leaks. Periodically check the air pressure and monitor for reduced water flow, lower storage capacity, or water leaking from the air valve, as these may indicate a failed diaphragm or a tank that needs replacement.

Complete your installation with compatible tank valves, pressure gauges, tubing, fittings, and sanitizing supplies. If you need help selecting the right reverse osmosis storage tank, our water treatment specialists are available to assist with sizing recommendations, custom solutions, and bulk pricing.