Do You Need a Tank for Reverse Osmosis? Find Out Here!
Written by: Gene Fitzgerald // Last Updated: Mar 13, 2023
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So, you’ve decided to install an RO system for water filtration. Great! But does that mean that you will have to have a large tank under your sink?
Reverse osmosis systems are not necessarily dependent on storage tanks, but you might need to consider getting one. Or not. Depending on your personal requirements.
Read on to see why you would want (or wouldn’t want!) to have an RO tank in place!
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Key Takeaways
- Tanks for reverse osmosis systems are not a must; there are also tankless units.
- Tank-based RO systems are a better option when you have a fridge or an ice maker you want to connect to.
- RO systems with tanks also do not require electricity. Purified water can be utilized even with no electrical connection or during an outage.
- RO tanks are perfect if you want to have gallons of purified water on hand.
Do You Need a Tank for Reverse Osmosis?
First of all, do you need a tank for reverse osmosis?
In theory, no, you don’t need a tank to purify water with a reverse osmosis system. After all, these systems also come in a tankless form.
So, why would anyone choose a tank if it’s not a necessity? Well, because RO tanks do bring certain benefits to your water supply…
When Are RO Tanks Important?
The most important function of the reverse osmosis tank is to provide you with pressurized RO water fast and on demand. As such, you won’t have to wait for your filtering system to produce even purified water to quench your thirst – the water is readily available.
But when is it absolutely important to have an RO storage tank?
Power Outage
Besides the usually fast output at your dedicated faucet, RO tanks make more sense if you’re dealing with frequent power outages. That is because they use air pressure, and do not depend on electrical pumps.
RO filtration is a rather slow process, and without a pump, it could take up to 5+ minutes to actually fill up a glass of pure water. If you live in an area that has an unsteady power supply, with an RO tank, you can always count on purified water in a matter of seconds.
Water Outage
The same goes for an obstructed water supply. If you’re usually dealing with short-term water outages in your area, the already-purified water in your RO tank might be enough to get you through that period.
Further Reading:
Bringing Purified Water to Your Fridge and Ice Maker
Of course, you can connect your fridge and/or ice maker to your RO system, even if it’s tankless. But there will be some “pulsing” involved.
The pulse happens as a result of the appliance using ONLY the water that is available in the water line. Once that quantity’s all used up, you have to wait for your RO system to purify more water.
And while this is not a malfunction, it could be overwhelming. It’s like making your fridge thirsty and giving it more water drop by drop.
The RO tank, here, comes in super handy. And for an obvious reason – because it already has a supply full of purified water. Even if your appliance is 16 feet away, it will still get enough filtered water to satisfy its needs. And guess what? No annoying pulsing involved!
What Is an RO Tank and How Does It Work?
The RO tank is, essentially, a storage tank where the water that’s been purified through the RO membrane and other filter stages goes. But it does more than merely store the water!
The tank consists of two different chambers, one for water, and one for air, separated by something called “a bladder” made from butyl.
That means that the tank is hydropneumatic and can deliver pressurized water on its own.
The water chamber is where the filtered water goes, and the air inside is in charge of giving pressure to the water.
When the RO water reaches the tank, the air chamber becomes compressed. This increases the internal pressure and gives you a solid water flow. The water from the RO tank gets pushed to your faucet fast, by simply using air against water, without any pump.
When the purified water fills the tank about 2/3 of the way, the air pressure nudges the system’s automatic valve to close. This is very important, as it stops more water from entering the filtration system and thus prevents water from continuously running down the drain.
Tank-Based vs. Tankless RO Systems – Which to Choose?
Tank-dependent RO water filtration systems were mainly used in the early, pre-pump stages of water purification. However, as previously explained, they do have more benefits than simply giving us that traditional feel.
In recent times, tankless RO systems have become more popular, though. They come with an internal pump that provides pressure, and do not take up that much space under the sink.
And while the tankless option may seem more attractive, the choice, though, is not a simple either-or decision. Both types of RO systems have a lot to offer. The question is – what do you want?
What to Consider
If you’re unsure whether you will benefit more from a tankless or tank-based RO system, ask yourself these questions:
- Do I have a tight budget for water filtration?
- Do I have a regular power and water supply?
- How much space do I have under the sink?
- Can I maintain a more expensive and complicated system? Or am I looking for a simpler option?
- Do I need to connect my fridge or ice maker to the filtered water?
Then go through the pros and cons below, respectively, and find your answer there.
Pros and Cons of a Tankless Reverse Osmosis System
A tankless RO system with a booster pump has a lot of benefits, but it also comes with a few drawbacks.
PRO: It Needs Less Space
Unlike their tank-based siblings, a tankless RO system can take up to a whopping 75% less space. If you have a cramped kitchen, this might seem like a good option for you.
PRO: Less Wastewater
With a tankless RO system with an internal pump, your wastewater per gallon of filtered water will be much lower – up to 90%. Compared to a standard RO system where the wastewater is 3-5 gallons per gallon of purified water, the tankless RO is a more eco-friendly option.
PRO: Purer Water
Pump-induced filtering increases the efficiency of the RO membrane. This further increases the pollutant reduction rates and provides you with water that has even lower traces of contaminants.
PRO: Fast Filtering
Although the tank system pushes clean water out of your faucet swiftly, the tankless systems can actually filter more gallons of water per day.
PRO: Easy to Maintain
A tankless RO system has three fewer components than a tank-based one. It is also easy to install and maintain.
CON: More Expensive
A tankless RO system has a built-in pump and is a more costly investment.
CON: Electricity-Dependent
Unlike a tank-based system, here, the water is pressurized thanks to the internal pump that runs on electricity. To filter water, you will need a steady electricity supply.
CON: No Water During an Outage
Since it runs on electricity and doesn’t store clean water in a tank, you will not be able to purify water with a tankless system during an electricity outage. Also, unless you haven’t previously filled a tank with clean water, there may be no purified water to utilize during a water outage, too.
CON: No Room for Customization
A tankless RO system is usually designed in a way that doesn’t allow you to attach extra filters (such as remineralization or disinfection) to the system.
Pros and Cons of a Tank Reverse Osmosis System
There are also a lot of advantages and disadvantages to consider with a tank-based RO system:
PRO: Affordable
Unlike the upgraded RO system, having a tank under the sink is a much more affordable option. Which is perfect if you’re looking to purify your water on a budget.
PRO: No Electricity Needed
The tank is hydropneumatic and the whole system runs on water pressure. That means that you don’t need to have electricity to have clean water (which is yet another reason why this option is more affordable).
PRO: Less Noise
Thanks to the fact that it does not use a pressure pump for filtering, a tank-based reverse osmosis system will make less noise than its tankless rival.
PRO: Easy to Customize
Having a standardized system means that you can add other filtration steps to it if you need to. You can easily incorporate a UV light or a remineralization filter for example.
PRO: Better for Connecting Fridges and Ice Makers
If you have a fridge you need to connect to, the tank-dependent RO system will be the better option, as the clean water stored in the tank allows for better water utilization for the appliance.
CON: More Space Needed
You will need to have a considerable amount of space under the sink to fit your tank.
CON: Secondary Pollution
Keep in mind that having a tank full of water makes it possible for re-contamination. Bacteria can grow inside and can easily pollute your already-purified water.
It is recommended to use some NSF-approved sanitizers to clean the inside of the storage tank once a year.
CON: Maintaining the Pressure
Checking RO tank pressure once a year is a must. If the pressure is low, you will have to increase it so that your RO system can run with efficiency.
If you have any thoughts about the question, do you need a tank for reverse osmosis, please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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