RO Tank Not Filling After Filter Change? Here’s What to Do!
Written by: Gene Fitzgerald // Last Updated: Mar 4, 2023
This page may contain affiliate links. If you buy a product or service through such a link we earn a commission at no extra cost to you. Learn more.
A common issue that often pops up after replacing old reverse osmosis filters is the storage tank no longer filling up.
This can happen for several reasons, so you’ll need to troubleshoot a little to find out the exact source of the problem.
Let’s break down some of the common reasons RO tanks stop filling up after recent changing filters.
Contents
show
Key Takeaways
Some common issues that can lead to an RO tank not filling after a filter change are
- Air locks – release the air by opening the RO faucet.
- The feed water valve being shut off – open the valve.
- The storage tank valve being shut – open the valve.
- A closed leak detector valve – open the valve.
- A filter element installed in the wrong direction – reinstall.
- Kinked tubing – remove any kinks.
- A faulty filter or membrane element – replace.
Why Is My RO Tank Not Filling After I Changed Filters on My Reverse Osmosis System?
Reverse osmosis systems are highly effective water filtration systems but due to their complexity, they are prone to occasional issues. Changing filters requires a bit of tinkering, so there will be chances to cause blockages in the system if you’re not careful.
Air in the System
Excessive air somewhere in the RO system may prevent water from flowing. This is called an air lock and can be the result of a recent filter change.
If you suspect an air lock in your reverse osmosis unit, close the storage tank valve, open the RO faucet, and allow water to run for several minutes. You might also want to try tilting the system module to about 45°.
Feed Water Valve Still Shut Off
A common mistake that’s easy to overlook is forgetting to shut the feed water valve back on.
The feed water valve is the valve that allows water to flow into the RO system from your sink’s cold-water supply. It must be shut off to replace the filter(s) and needs to be turned back on for water to flow into the system once you’re done.
Further Reading:
Storage Tank Valve Still Closed
Another easily overlooked issue is forgetting to open the storage tank valve. If this valve is shut off, no water will flow from the RO membrane outlet into the storage tank.
Open this valve by turning it to the open position, and your tank should begin filling up with filtered water if that was the issue.
Leak Detector Valve Closed
A leak detector valve is a built-in failsafe designed to shut off the system if a leak is detected.
These valves generally work well and do a good job protecting against leaks, but sometimes they’ll trigger even if there’s no leak. Spilling some water during filter changes can trigger the leak detector valve, which will need to be reset for the system to start working again.
These valves have small absorbent tablets that expand to shut off the water supply. Unfortunately, this can also happen from spilling water accidentally.
This issue can be easily fixed by replacing the expanded pad with a new one – so if you have a leak detector valve, it’s a good idea to keep a few of these pads on hand.
You Installed a Filter Element the Wrong Way
Filter elements – especially carbon filters and the RO membrane – are designed to be installed in a particular direction, and won’t work if they’re installed backward. These filter cartridges typically have an indication arrow on their side to let you know which way they need to be installed.
This is a fairly easy problem to locate and solve, all you need to do is shut off the feed water supply, remove the filters from their housings, and ensure they are installed in the correct direction.
Kinked Tubing
Kinked tubing is another issue that may be preventing water from flowing into your reverse osmosis tank. When installing an RO system, you generally want to utilize the shortest possible lengths of tubing between fittings to prevent this.
You can locate a kinked tube by taking a look at your entire RO system. Look for any sharp bends or kinks in the lines that could be impeding the water flow.
Fixing this issue is fairly simple. When you find a kink in your tubing, remove the section of the tubing and either shorten it or replace it with a fresh tubing section.
You Installed a Bad Filter or Membrane
This one is a rare occurrence, but once in while you’ll encounter a faulty filter or RO membrane that doesn’t work properly. If you run through all of the other troubleshooting steps and your storage tank still won’t fill up, then there is a possibility that your filters are defective.
You’ll only know for sure until you replace the filter or membrane in question with a new one.
How Long Does It Take to Fill a Reverse Osmosis Storage Tank?
It’s important to remember that reverse osmosis storage tanks don’t fill up instantly, so you might be thinking that your storage tank isn’t filling when in reality it is just filling slowly.
Generally speaking, a typical 4-gallon storage tank will take between 2 and 4+ hours to fill completely. This assumes that everything is working properly and there are no clogs or blockages in the system.
Several factors that go into the tank filling rate, including your home’s water pressure, the storage tank size, the condition of the membrane and filters, the water temperature, and the type of RO system you have.
Home’s Water Pressure
For your RO system to operate optimally, the water pressure should fall somewhere between 60 and 80 psi. The system will still work down to 40 psi, but this is less than ideal and will result in slower operation.
If your home’s water pressure is higher or lower than the recommended range, it may be worth investing in either a pressure regulator to lower water pressure or an assist pump to increase it.
Membrane and Filter Condition
As you might expect, the condition of your RO system’s membrane and filters will have a major impact on how efficiently it works. An older or clogged membrane/filter will slow down the flow rate through the system – leading to a slower storage tank filling speed.
Water Temperature
Generally speaking, water temperature does not have a major impact on the performance of your RO system, but water temperatures approaching freezing will slow the system down significantly.
Most of the time this is not an issue even in cold temperatures, as the heating and insulation in your home will keep the feed water warm enough for the RO system.
Type of RO System
The type of RO system you’re dealing with will also have a major impact on your storage tank’s filling speed. RO systems come in different GPD (gallons per day) output ratings, which indicate the maximum output of filtered water per day.
Higher rates of water filtration will result in a faster storage tank filling speed, so if your system has a 100 GPD rating, the storage tank will fill faster than a 50-GPD system tank.
If you have any questions about why your RO tank isn’t filling after a recent filter change please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
Information provided on BOS is for educational purposes only. The products and services we review may not be right for your individual circumstances.
We adhere to strict editorial guidelines. Rest assured, the opinions expressed have not been provided, reviewed, or otherwise endorsed by our partners – they are unbiased, independent, and the author’s alone. Our licensed experts fact-check all content for accuracy. It is accurate as of the date posted and to the best of our knowledge.