Although RO water is pure, it will not keep longer than two years. This is because the container used to store RO water releases metals or synthetic nutrients over time. Also, sometimes algae or fungi will pass through the filter. If the RO water is exposed to light, this can cause algae or fungi to grow.
How long RO water can be stored?
Unopened bottled water can be used for up to 1 or 2 years while once they’re opened, it can be stored for up to two weeks. RO/UV purified water can be stored up to 6 months or even longer, again depending on the storage container.
Can you get sick from drinking old water?
The water left overnight or for a long period of time in an open glass or container is home to numerous bacterias and is not safe for drinking. You never know how much dust, debris, and other small microscopic particles might have passed into that glass. Water left in a bottle for a long time is not safe to drink.
How to store RO water and keep it fresh for a month?
Keep it cool, dark, and aerated and you should be fine for a while. The UV would be worth looking into, I know they sell systems for keeping decorative outdoor ponds clean, so they have the capability of treating large amounts of water.