How Long Can You Store Reverse Osmosis Water Before It Goes Bad?
Written by: Alexandra Uta // Last Updated: Sep 1, 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.
Storing reverse osmosis water for later use is probably the most common way of alleviating the slow operation of reverse osmosis systems.
If you’re wondering whether prolonged storage can lead to potential problems, and what the reasonable time limit for storing reverse osmosis water is, read on!
Contents
show
Key Takeaways
- Under the right conditions, you can store reverse osmosis water for several months and longer.
- It’s important that the storage container doesn’t leach chemicals into the RO water, and that the water doesn’t get contaminated with germs.
- With home reverse osmosis systems, RO water should sit no more than a few days in the storage tank. Otherwise, the water will take on an unpleasant taste/odor.
How Long Can You Store Reverse Osmosis Water
So, how long can you store reverse osmosis water?
You can theoretically store reverse osmosis water indefinitely, provided you have the ideal storage conditions available. In reality, achieving those conditions is very hard for regular domestic users. That’s because you have to pay attention to the storage material to ensure that it won’t leach anything into the water, isolate the stored water from the surrounding environment as much as possible, and possibly even control factors like storage temperature.
Reverse osmosis systems typically come with a storage tank. This is only meant as a temporary buffer though, and shouldn’t be used for long-term storage. Otherwise, water can develop a plastic taste due to the material used for the interior of the bladder. It only takes a few days for this to happen, so you should try to adjust your water consumption to ensure that RO water in the tank gets completely used in 1-2 days.
Therefore, short-term RO water storage is easy enough if you just use your storage tank properly. If you want to store reverse osmosis water for a few weeks or even months, we recommend food-grade water bottles. This is a cheap and effective method of storage that can easily last 3-4 months. You could potentially store water even longer in a food-grade bottle, but this increases the risk of bacteria developing in the container.
Metal containers are another viable option if you only need to store water for a few weeks or a couple of months. We recommend going with stainless steel and avoiding copper – we’ve explained why in more detail below.
For even longer storage, you can use a food-grade plastic barrel. This is an easy solution for storing large amounts of reverse osmosis water – with more than 50 gallons per barrel, you’re only limited by the amount of storage space you have for keeping the barrels themselves. Some users also recommend adding a heater to maintain a certain temperature, though that’s not strictly necessary unless you live in an area with strong weather fluctuations.
Keep in mind that storing reverse osmosis water for more than six months is pushing it a bit. Storing reverse osmosis water for that long is not recommended unless it’s absolutely unavoidable, no matter what kind of container you might use. Even a high-grade stainless steel container will likely give your water a slight metallic taste after that much time.
Does Reverse Osmosis Water Ever Go Bad?
Pure water doesn’t contain anything that can spoil or go bad, so reverse osmosis water can’t really go bad by that definition either. However, this changes as soon as any contaminants start to find their way into your stored water. This can happen for a number of reasons:
- Chemicals from the storage container leaching into the water
- Germs entering the stored water and reproducing
- Debris from the surrounding environment falling into the container – this is especially problematic if you store your water in an open container
Biological contamination is often the biggest issue. If water is left stagnant for too long, especially in a container that’s at least partially exposed to the environment, various germs will start growing in it sooner or later. You may be able to counteract this by running your stored water through a UV filter, but that will add an extra layer of complication to your setup.
Can You Get Sick from Drinking Old RO Water?
This depends on how the RO water was stored and how old it is exactly, but the short answer is yes, you can absolutely get sick from drinking old reverse osmosis water. Biofouling is the biggest concern in this regard. No matter how careful you are, it’s very difficult to prevent germs from entering your storage container after a while. This is why you shouldn’t rely on any storage method for more than a few months, or a year at most.
Old reverse osmosis water may also contain traces of the material used in the storage container. The longer it’s been stored, the higher the concentration will be. While this may not make you sick in most cases, it can lead to problems with specific materials like copper.
Tips for Storing Reverse Osmosis Water and Keeping It Fresh
If you’re looking to make the most of your reverse osmosis water storage and minimize the risk of ending up with contaminated water down the line, here are some tips to keep in mind:
- Only use approved food-grade containers, especially if planning to store RO water for longer than a couple of days/weeks. Otherwise, you risk having the container’s material leach into the water.
- Keep your containers in a dry, cool place. Avoid exposure to sunlight as it can promote the growth of bacteria and algae.
- Ensure the containers are tightly sealed. Even a small crack can be enough for contaminants to make their way inside.
- Use labels and/or maintain a calendar for larger batches stored for longer periods of time. You should have some way of tracking when each container was sealed and last opened.
- Sanitize each container before filling it. We recommend starting with regular soapy water, and then using a bleach solution for thorough sanitization. Mix unscented household bleach (check the label and look for products with 5% – 9% sodium hypochlorite) with water at a ratio of 1 teaspoon per 4 cups, then use that to clean your container and rinse it thoroughly once you’re done.
- NEVER use containers that have been previously used for storing toxic chemicals, whether liquid or solid. No matter how thoroughly you might think you’ve cleaned the container, even a minimal trace amount of the original chemical can be enough to poison your water if the container is used for long-term storage.
- Do not touch stored water with your bare hands. Always use a sanitized container for scooping water out of long-term storage.
Further Reading:
Copper Containers?
While copper is a very popular material for water bottles and some users exclusively use copper bottles for their daily drinking, reverse osmosis water should be treated as a special case. Especially when it comes to long-term storage. The problem is that reverse osmosis water is slightly acidic and highly pure, which causes severe corrosion in copper. As a result, copper will start leaching into the stored RO water.
Normally, this isn’t a problem if you use a copper bottle for daily drinking and don’t keep water in it for too long. But if reverse osmosis water has been stored in a copper container for several weeks, it will likely have a very high concentration of copper, to the point where it can pose a serious health risk.
If you have any questions about RO water shelf life please don’t hesitate to leave a comment below!
About the Author Alexandra Uta
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.