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Reverse osmosis storage tank (Best pressurized)

The reverse osmosis system treats water slowly, so you need a storage tank that will collect purified water that is gradually treated. Without the tank, you can end up waiting for long to fill a glass of water or a pot when you open the kitchen faucet. The tank collects water so you can have immediate access to treated water.

Reverse osmosis storage tank

The reverse osmosis storage tank is designed to be stored under the sink in line with your under sink reverse osmosis system.

The storage tank is where filtered water is stored waiting to be transported to its point of use. Storage tank comes in different sizes and this depends on the amount of water your family consumes

Reverse osmosis tank comparisons

 NameImageFeaturesWhere to buy
1Express Water RO132-TNK 4.0 gal Reverse Osmosis RO Water Storage Tank by TANKROPre-pressurized / Pre-charged-7-10psi
Capacity -4 gallons and 3.2 gallons RO processed water
Connection - Water valve 1/4" at the top
Certification -NSF certified
Material -food-grade material-stainless steel, polypropylene, and butyl rubber
Dimension-15x 11 x 11 inches
Come with stand and tank ball valve
Check Amazon
2iSpring T32M 3.2 Gallon Pressurized Storage Tank for Reverse Osmosis (RO) SystemsPre-pressurized / Pre-charged-7-10psi
Capacity -up to 3.2 gallons
Connection - Water valve 1/4" at the top
Certification -NSF/ANSI Standard.
Material -food-grade steel, chlorobutyl diaphragm, and polypropylene liner
Dimension-14 x 11 x 11 inches
Come with a stand and tank valve
Check Amazon
3PA-E Reverse Osmosis RO Water Storage TankPre-pressurized / Pre-charged
Capacity -6 gallons and holds 5.5 gallons of water
Connection - Water valve 1/4" at the top
Certification -NSF, IAMPO approved, and CE
Material -food-grade steel, chlorobutyl diaphragm, and Virgin polypropylene liner
Dimension-16 x 11 x 11 inches
Come with stand and no tank valve
Check Amazon
4APEC Water Systems TANK-4 4 Gallon Residential Pre-Pressurized Reverse Osmosis Water Storage Tank, WhitePrecharge/pre-pressurized-5-7Psi pressure of air
Capacity -4 gallons and holds 3.2 gallons of water
Connection - Water valve 1/4" at the top
Certification -
Dimension-14.5 x 11 x 11 inches
come with a stand and no tank valve
Check Amazon
5Watts Premier 119008 10-Gallon White Metal Pressure Storage Water TankPrecharge/pre-pressurized-5-7Psi pressure of air
Capacity -10 gallons
Connection - Water valve 1/4"
Certification - NSF tested and certified against ANSI/ NSF Standard 61
Dimension-23.5 x 16 x 16 inches
come with a stand and no tank valve
Check Amazon
6CrystalClear Reverse Osmosis Plastic Storage TankPrecharge/pre-pressurized-5-7Psi pressure of air
Capacity -4 gallons
Connection - Water valve 1/4"
Certification - NSF tested and certified
Dimension-14 x 11 x 11 inches
Inbuilt stand and no tank valve
Check Amazon

How does a reverse osmosis tank work?

Most people ask themselves as they physically look at the tank, the way out is at the top not at the bottom as many tanks. How does the tank deliver water right on your faucet or point of use?

Reverse osmosis tanks use air pressure to deliver water to the kitchen faucet. The air pressure help deliver water without the use of a booster pump.

Inside the tank, there is an air pressure chamber and water pressure chamber. The air pressure chamber is at the bottom while the water chamber at the top.

As purified water gets into the storage tank, the weight of the water will compress the air chamber. The more the air chamber compresses it will continue to increase the pressure. When you open the faucet the pressure will force water out of the tank to the faucet.

If the tank did not have pressure even if is filled with water it will not be capable of delivering water to the faucet unless you are using the delivery/demand pump.

So reverse osmosis tanks are special they are Pre-Pressurized to provide water efficiently to the faucet.

In case your tank that came to the RO system is not providing water and you have done troubleshooting you need to replace the tank by buying a new one.

That’s why we have provided a review of reverse osmosis storage tank replacement

Best Pressurized reverse osmosis storage tank 2021

Pressurized RO storage tank reviews
  1. Express Water RO132-TNK 4.0 gal Reverse Osmosis RO Water Storage Tank by TANKRO

Specification

  • Pre-pressurized / Pre-charged-7-10psi
  • Capacity -4 gallons and 3.2 gallons RO processed water
  • Connection – Water valve 1/4″ at the top
  • Certification -NSF certified
  • Material -food-grade material-stainless steel, polypropylene, and butyl rubber
  • Dimension-15x 11 x 11 inches
  • Come with stand and tank ball valve

The tank pre-charge about 5-7 psi

Tankro tank is manufactured using the finest FDA best material such as stainless steel, polypropylene, and butyl rubber.

This tank has a capacity of 4 gallons and holds 3.2 gallons for on-demand filtered drinking water.

The water valve fits 1/4″ NPT and the air valve is made from durable brass for pressure adjustment. It comes with a tank ball valve.

When it comes to warranty the tank has 1 year warranty and is NSF certified.

The tank is designed to fit under most kitchen sinks inside the cabinet and come with a stand to secure the tank.

Where to keep reverse osmosis tank

TankRO Reverse Osmosis Water Storage Pressure Tank Reservoir is available in different capacity

  1. iSpring T32M 3.2 Gallon Pressurized Storage Tank for Reverse Osmosis (RO) Systems

Specification

  • Pre-pressurized / Pre-charged-7-10psi
  • Capacity -up to 3.2 gallons
  • Connection – Water valve 1/4″ at the top
  • Certification -NSF/ANSI Standard.
  • Material -food-grade steel, chlorobutyl diaphragm, and polypropylene liner
  • Dimension-14 x 11 x 11 inches
  • Come with a stand and tank valve

The tank size is 3.2 gallons and designed for reverse osmosis application.

To guarantee safety, the tank is constructed using stainless steel, food grade material, and FDA compliant material. The water chamber is made from food-grade butyl diaphragm and polypropylene coating to provide tasteless and odorless water.

It is by independent third-party to meet NSF/ANSI Standard.

The tank is Pre-pressurized between 7-10 psi for common use

This tank discharges effectively in both vertical and horizontal position.

The tank has water valve that fits 1/4″ NPT and standard air valve/nozzle for pressure adjustment

Ispring RO water storage tank is available in different capacity

  1. PA-E Reverse Osmosis RO Water Storage Tank
RO storage tank

Specification

  • Pre-pressurized / Pre-charged
  • Capacity -6 gallons and holds 5.5 gallons of water
  • Connection – Water valve 1/4″ at the top
  • Certification -NSF, IAMPO approved, and CE
  • Material -food-grade steel, chlorobutyl diaphragm, and Virgin polypropylene liner
  • Dimension-16 x 11 x 11 inches
  • Come with stand and no tank valve

To ensure you are consuming standard water the tank is manufactured using FDA compliant material and food-grade material. The water chamber is made with a High-grade chlorobutyl diaphragm and Virgin polypropylene liner

It is NSF approved under standard 58 and 61,  IAMPO approved, and CE approved under the PED (pressure equipment directive).

The tank size is 6 gallons and hold 5.5 gallons of treated water.

this tank has 1/4″ Stainless steel water connection and Smooth internal air vent cap. It does not come with tank ball valve.

It also features four nubbins protrude at the bottom that allows it to sit upright and level

Cons

  • No tank valve

PAE RO-132 RO pressure tank 4 gallon

Specification

  • Precharge-5-7Psi pressure of air
  • Capacity -4 gallons and holds 3.2 gallons of water
  • Connection – Water valve 1/4″ at the top
  • Certification -NSF and CE
  • Dimension-15 x 12 x 12 inches
  • come with a stand and no tank valve

To make sure the tank is safe for human use it is certified by NSF and CE. It is also made of FDA approved bladder, food grade, no rubber smell, no plastic smell, stainless steel connection on top

 The tank is 4 gallons and holds 3.2 gallons of water

It is pre-charge with the 5-7Psi pressure of air.

This tank come with tank stand and water inlet is 1/4″ NPT with stainless steel thread.

Cons

  • No tank valve

PA-E RO-122 small Reverse Osmosis Water storage pressure tank

Specification

  • Precharge-5-7Psi pressure of air
  • Capacity – 3.2 gallons of water
  • Connection – Water valve 1/4″
  • Certification -NSF Approved
  • Dimension-14 x 9 x 9 inches
  • Material-food grade, post-cured diaphragm Virgin polypropylene liner
  • come with a stand and no tank valve
  1. APEC Water Systems TANK-4 4 Gallon Residential Pre-Pressurized Reverse Osmosis Water Storage Tank, White

Specification

  • Precharge/pre-pressurized-5-7Psi pressure of air
  • Capacity -4 gallons and holds 3.2 gallons of water
  • Connection – Water valve 1/4″ at the top
  • Certification –
  • Dimension-14.5 x 11 x 11 inches
  • come with a stand and no tank valve

APEC water system 4-gallon pressurized tank holds 3.2 gallons of water.

The tank comes with a stand and can you can easily position it vertical or horizontal.

It is made from food-grade polypropylene and butyl reservoirs. The quality of the material ensures tasteless, odorless, and contaminant free water. 

This tank has ¼ inch stainless steel connection and a sealed brass air valve. It is compatible with ¼ inch tank ball valve but does not come with it.

APEC water systems tank is available in different sizes

  1. Watts Premier 119008 10-Gallon White Metal Pressure Storage Water Tank

Specification

  • Precharge/pre-pressurized-5-7Psi pressure of air
  • Capacity -10 gallons 
  • Connection – Water valve 1/4″ 
  • Certification – NSF tested and certified against ANSI/ NSF Standard 61
  • Dimension-23.5 x 16 x 16 inches
  • come with a stand and no tank valve

Watts Premier Pressure Storage Water Tank is made from metal. Inside the tank has a polypropylene liner and utilizes a butyl diaphragm for the water storage area.

It features a 1/4 in. male stainless steel connection, a Shrader valve for checking air pressure, and a tank stand.

This tank is NSF tested and certified against ANSI/ NSF Standard 61

Watts storage tank has a capacity of 10 gallons 

  1. CrystalClear Reverse Osmosis Plastic Storage Tank

Specification

  • Precharge/pre-pressurized-5-7Psi pressure of air
  • Capacity -4 gallons 
  • Connection – Water valve 1/4″ 
  • Certification – NSF tested and certified 
  • Dimension-14 x 11 x 11 inches
  • Inbuilt stand and no tank valve

CrystalClear Reverse Osmosis Plastic Storage Tank is made from food-grade polypropylene 

The tank is NSF certified and has a 1-year warranty

40 gallon
40 gallon reverse osmosis tank

40 gallon is a large reverse osmosis tank

TankRO – RO Water Filtration System Expansion Tank

Specification

  • Pre-pressurized / Pre-charged
  • Capacity -40 gallons and up to 22 gallons of water for on-demand filtered drinking water.
  • Connection – Water valve 1″ at the bottom
  • Certification -NSF certified
  • Material -food-grade material-stainless steel, polypropylene, and butyl rubber
  • Dimension-38 x 18 x 18 inches
  • Come with stand and tank ball valve

iSpring T40M 40 Gallon Pre-Pressurized Tank for Reverse Osmosis (RO) Systems

Specification

  • Pre-pressurized / Pre-charged
  • Capacity -40 gallons
  • Connection
  • Certification -meet NSF and ANSI Standard
  • Material -food-grade material-stainless steel, polypropylene, and butyl rubber
  • Dimension-41 x 17 x 17 inches
  • Come with a Shut-off valve, tank connector, and tank stand 

What to consider when buying a reverse osmosis storage tank

  • Capacity

Capacity is the amount of water the tank is capable of holding.

The storage tank comes in different sizes measured in a gallon. The size you require depends on your household usage. If you have a large family you need a bigger tank for you to get enough water and vice versa.

In addition to the capacity of the storage tank, you should know the tank does not hold the amount of water the manufacturer says. If your tank is labeled 4.5 gallons remember that tank has two chambers inside one for the air and the other for water. You will find that the tank will hold 3 gallons of water and the other part will be occupied by air that is 70% water and 30% air. 

The 4.5 gallons is the total amount of water the tank will hold without air but if it is pre-pressurized it will hold less. 

  • Material

Reverse osmosis tank should be made using quality material. Make sure the tank or connections does not have material such as Lead, brass and copper. These materials were banned for use in purified/drinking water.

Material such as food-grade stainless steel and brass is okay. The chamber should be made from food-grade polypropylene and butyl reservoirs. Also, the quality of material ensures tasteless, odorless, and contaminant-free water.

Can I increase the tank capacity with a second tank?

You can find the case where you bought a RO system with small tank storage capacities in such incidences you will receive less water required for your household. 
You can increase the tank capacity by adding the second tank.
Also, there are incidences you will find the tank is getting less water than its capacity you can increase the capacity by adding booster tank.
This happens if the water supply has low pressure, more water will go to waste and less water will go through reverse osmosis membrane leading to less water going to the storage tank.
By increasing incoming water pressure the tank will accumulate treated water faster.

How do I add pressure back to the tank if lost?

3-5 gallons tanks are recommended to have 7-10 psi. If the pressure is below 7 psi you need to increase pressure.
If the storage tank has lost its pressure there is an air valve at the tank mostly at the bottom part you can use to add pressure.
You can use a bicycle/electrical pump to add pressure to the tank.

How long does the storage tank last?

Most storage tank last 10-15 years

How do you know it’s time to replace the storage tank?

Counting 10 years or so is not easy for you to know it’s time to replace the storage tank but some signs can tell you it’s time to replace the tank. Such as 
If you add pressure to the tank as described above and purified water fails to come out of the tank to faucet it’s time to replace the tank.
If the water comes out at the air valve this means the bladder that divides air and water chamber is damaged. There is no way to repair the bladder that means the tank requires to be replaced.

FAQ

How to add a pressure tank using a bicycle pump

Open the cap covering the valve. Use a bicycle pump to ad pressure. The standard pressure required for the majority of the tank is 7PSI. You can use a pressure gauge to monitor pressure not to over/under pressure. Add pressure until water will start coming out of the tank.

If you add more pressure that required that is above 7psi you will reduce the amount of water the tank will hold.

Reverse osmosis tank pressure 

The standard pressure required for the majority of the tank is 7PSI

Reverse osmosis tank not filling up

There are incidences you will find the tank is not filling up. 

If the tank is not filling up it is mostly caused by feed water pressure (check the water pressure gauge to measure your incoming water pressure). If the feed water pressure is low, water is not capable of going through the RO membrane leading to more water wastage, therefore the system produces less purified water to go to the storage tank.

If less water is purified you will end up having your storage tank not filled with water.

To solve the problem increase your incoming water pressure using a booster pump 

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