Written by: Gene Fitzgerald // Last Updated: Mar 4, 2023
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When it comes to reverse osmosis systems, there are but few parts more pivotal than the water storage tank.
Most people with a reverse osmosis system never really think about the process it takes to fill their system’s tank.
Let’s get started answering the question of how long it takes to fill a reverse osmosis tank!
Key Takeaways
So, how long does it take to fill a reverse osmosis storage tank?
The standard reverse osmosis storage tank is about 2.8 gallons. This type of tank takes between 2-4 hours total to fill.
That said…
How long your RO tank takes to fill precisely depends on several different factors. These are:
Quite simply, a larger tank requires more time to fill provided that system flow rate stays the same.
The water pressure fed to a reverse osmosis system greatly affects how long the storage tank takes to fill. If your home has a problem with low water pressure, then you’ll be seeing it take longer than it’s meant to take. This is because the water is moving slower through the RO system.
The minimum pressure requirement for an RO system is 40 psi. Anything lower, you’re looking at a system that’s not going to work as well as it should – and a tank that might never fill up. Beyond the minimum water pressure, the optimum is between 60 and 80 psi.
Age is always a factor in just about any product you buy.
When a reverse osmosis water filtering system has been around for a while, it’s going to start showing signs of wear and tear. One of the most obvious signs of an ageing RO system is when the filters get clogged.
This is an easy fix and requires you to ensure you’re properly maintaining your RO system by changing various filter elements in due time. How often? It could be anywhere between six months and a couple of years, depending on the type of filter, your water quality and usage, and more. Tip: Check your product manual!
This is a rare determinant of an RO tank filling too slowly. It’s more common when the temperature dips below 40 degrees Fahrenheit. A low water temperature like this can significantly reduce how quickly the reverse osmosis membrane can produce filtered water. This only gets worse as the water reaches its natural freezing point.
There are different types of reverse osmosis systems. Some are designed to be faster or produce more filtered water. You can check flow rates in product descriptions to ensure you’re getting the kind of RO system you want. Surprisingly, some of the larger RO storage tank systems actually fill faster than smaller tank units.
Standard under sink RO systems can produce two to three ounces of filtered water every minute. It takes longer to fill the tank, as mentioned previously, but if you attempted to fill a glass of water immediately, you’d be waiting roughly five minutes just to fill the one glass.
Not necessarily. While this might be true in some cases, you need to ask yourself, at what cost? Depending on the omitted stages, will the water still be as good?
At the same time, a water filter with too many stages decreases the pressure in the water, which can mean it does get slower. So you need to consider what fewer or more stages mean for the quality of the water produced.
Okay, the first step is to not freak out. There’s likely a very logical reason for this dilemma. So, let’s take a look at some of the reasons why your RO system tank isn’t filling up.
When you’ve got a closed feed water valve, you’re not getting any water into the RO system at all. All you need to do in this scenario is to find the feed water valve (most likely under your kitchen sink) and open it.
This is similar to the feed water valve, except this time, there’s water, but it’s not being given access to the tank. Ensure the tank valve is open to allow water to be stored inside.
Not all RO systems will have a leak detector, but for the ones that do, be wary of why you’re not getting any water. If the leak detector detects a leak, it will shut off all water access to the system and tank.
We’ve covered this before. If there’s not enough pressure, the RO membrane won’t let enough water through to fill the tank properly. Instead, most water will flow down the drain line wasted.
So, you’re going to need to ensure the feed water pressure is adequate.
One of the more obvious problems you might be having is clogged filters or a clogged RO membrane. When clogged, the water will either struggle or not get through at all.
When we say kinked tubing, we’re talking about a kink that exists in the RO systems tubing that’s either restricting or slowing down the water flow. When the water flow is disrupted, you’ll find the tank is either filling up slowly or not at all.
Just like low feed water pressure causes the water to be unable to travel, high backpressure from the tank won’t even let the water near it. So you need to address the pressure by draining the tank and resetting it.
Another problem might be a ruptured tank bladder as a result of pressure issues or simple wear and tear. In the event of a ruptured tank bladder, you’re going to have to replace the entire tank.
Air inside your reverse osmosis system is often a side effect of replacing filters. To release any air, open the RO faucet while tilting your system module.
Some RO systems are low-flow and, in turn, take far longer to fill the tank, and that’s if they’re able to at all. If the pressure isn’t enough to compensate for the backpressure of the tank, then said tank is not going to fill.
To understand how an RO tank works, you need to understand one particular detail about them: They contain pressurized air. This is important because by using pressurized air, a reverse osmosis storage tank is able to get the water up the sink and out the RO faucet without using an electric motor.
We also refer to these tanks as hydropneumatic storage tanks. These tanks are able to provide pressurized water when needed, and do so quickly.
Hydropneumatic storage tanks have both a water and air chamber, which are divided by a bladder. Water doesn’t compress, but air does. When water enters the storage tank, it compresses the air chamber, which increases pressure inside the tank.
Once the water reaches a certain level in the RO tank, meaning the backpressure is high, it causes the automatic shut-off valve (ASO) on your reverse osmosis system to close therefore stopping water from continuing to enter. This is why RO tanks cannot overfill. It also prevents water wastage because, otherwise, purified water that exceeds the capacity of the tank would simply flow down the drain. Once water is taken out of the storage tank and (back)pressure goes down, the ASO opens up and more water gets purified.
By the way, a tank’s size will determine where the water actually sits in the tank. When the tank is smaller (1-10 gallons) the air sits below the water which is on top. As tanks get larger this shifts to the opposite. It’s water on the bottom and air on top.
If you have any thoughts about the question, how long does a reverse osmosis tank take to fill, please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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when the shut off valve stops the water from filling the tank what about the water that’s still coming from the outside tap if u was to be out and left it to fill while u was gone
ReplySorry Liam, I’m not quite sure what your question is. Could you elaborate, please?
Reply