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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!
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.
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:
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.
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.
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:
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!
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