Can You Add a Second Tank to Your RO System (or Multiple)?
Written by: Gene Fitzgerald // Last Updated: Mar 13, 2023
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Peak times in any household can be crazy. Running around, trying to get everything ready and organized, everyone filling up their water bottles for work or school, and drinking glasses of water.
The last thing you want is to turn on your RO faucet and find not enough is coming out, or only a slow trickle after the first ounces.
Sound familiar? If it does, you may be wondering how to increase the water storage capacity of your RO system. One option is to install a second tank! Let’s discuss that process and see if it is right for you.
Contents
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Key Takeaways
- You can add a second or even multiple tanks to your existing RO system if you are using more water at peak times than your original tank can hold.
- Using 2 or more tanks will also keep water pressure from your RO faucet higher for longer. The same goes for RO water pressure supplied to refrigerators and ice makers.
- The tanks should be similar in size and should run parallel (set up with a T-valve).
Can You Add a Second Tank to Your RO System to Increase Capacity?
It is possible to add a second (or even a third!) storage tank to your RO system to increase its water-holding capacity?
Yes, it is possible. The tanks will work together and improve the water delivery as two tanks mean more water in total and also higher water pressure for longer. Meaning, water pressure from your RO faucet won’t decrease as fast after filling a few glasses.
This is particularly useful if you use RO water for your refrigerator/ice machine. With two tanks, the water line that runs to your fridge will pull water from both of the tanks simultaneously, which means the amount of water that leaves each tank is reduced, and the pressure will remain high for an extended period. Not to mention, you will also have double the amount of water for when you need it!
How to Use 2 or Multiple Storage Tanks with 1 RO System
Installing a second RO tank is a relatively simple procedure, providing you have the space. You will need a second tube and a ‘T’ connector to tie the two tanks together.
What’s important is that the tanks must be installed parallel to each other, not one after the other.
Equipment
You will need a second tank, a T-connector, tubing, and a utility knife.
Step by Step Instructions
- Turn off the water supply and the existing storage tank valve.
- Open the RO faucet and drain as much water out of the system as possible.
- Disconnect the tubing that links the existing tank to the RO system.
- Depending on your setup, you can cut the tubing with the utility knife and put the T-connecter in the middle or at the end.
- Ensure the valve on the new tank is installed correctly.
- Connect both the new and the old tank to the tee.
- Open both of the tank valves and turn on the water supply.
- Wait for the tanks to fill and check for leaks as they do.
Further Reading:
Pros and Cons of Adding a Second Reverse Osmosis Tank
More Water
The main pro of having a second RO tank is an increase in your system’s filtered water holding capacity. This is particularly useful if you have found that you are using more RO water than you thought you might need or if the number of occupants in your household increases.
Higher Pressure for Longer
Having a second tank will make a noticeable difference in the flow rate of water from your RO faucet or ice maker. When dispensing water, the pressure will be higher for longer.
Refrigerators and Ice Makers
A second tank ensures enough water travels to your fridge and ice maker, so you end up with proper ice cubes, not tiny ones.
Stagnant Water
One of the downsides to having two or more reverse osmosis storage tanks is an increased risk of biofilm and bacteria accumulating, mainly if your water demand isn’t that high and the water is sitting stale for quite some time.
That’s why you should only add another tank to your RO setup if there really is demand for it.
Do the RO Tanks Have to Be…
Of the Same Size?
While the tanks do not have to be the exact same size, it is recommended to have the second tank at least close to the same size as the first. This ensures that they work simultaneously, rather than one tank doing most of the legwork and the second only kicking in when the water usage is high (the tank with the more substantial air pressure might end up providing all the water while the other stagnates).
Of the Same Brand?
The two tanks do not have to be the same brand, as most RO tanks work the same way. Just make sure whatever you purchase is good quality and that the new tank is also an air-charged storage tank. If the tubing size is different, you can use an adapter.
In the Same Location?
Having the tanks in the same location is better, but if you cannot, you can place them in different locations – but not too far away. Also, make sure you are going to be using the water. If the second tank is further away, your RO faucet will primarily draw from the first tank until water pressure is low, and then the tank second afterward. This is an issue if you do not use enough water and the second tank is left to stagnate.
If you have an ice maker, a second tank near the refrigerator is a great idea.
Using Multiple Tanks vs One Large Tank
If you have a choice between installing an extra reverse osmosis tank, and upgrading to a larger tank, then the latter is the better option to decrease the risk of stagnant water sitting in a second tank.
Reverse osmosis filtration starts as soon as you remove a little water from the tank, so if it is being used gradually over the entire day, a 4-gallon tank could end up giving you about 24 gallons of water over a 24-hour period.
A second tank is beneficial if you are using a lot of water in a short span of time.
What Are Reverse Osmosis Pressure Tanks and How Do They Work?
Reverse osmosis pressure tanks are hydropneumatic, which means they contain both water and pressurized air. The outer is usually steel or fiberglass, and the inner is lined with butyl, a material that stops the steel from leaching into the stored water.
The tank’s purpose is to store the water produced by very slow RO filtration so that you always have some ready to use. When you open the RO faucet, the air pressure in the tank will send the water up and out of the spout without any need for electronic pumps or motors.
This pressure also causes the triggering of the automatic shut-off valve (ASO). When the tank is full and the pressure is at its maximum, the valve is triggered, and the system will stop filtering and adding more water to the tank. When you pour yourself a glass of water, the valve will switch again with the pressure drop, and your machine will start to filter once more to replace the water.
If you have any questions about using multiple RO storage tanks please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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