How Long Can Water Be Stored For? Is It Safe After 1 Year?

How Long Can Water Be Stored For? Is It Safe After 1 Year? by  for Modern Survival Blog

I received an email basically asking how long can water be stored for.

I was asked for my opinion about the safety of drinking water that has been stored for a year under specific conditions. Including being exposed to higher than normal temperatures during the summer.

Here is the question and my answer.


Water from a city municipal system which is treated and filled into a clean BPA-free 55 gallon dark blue barrel.

Bungs are tightened and sealed and the barrel is placed out side, siting on bricks to allow for air flow.

Outside temps during the summer months are about 105 degrees F for roughly 3 months.

Would that water be safe to consume after say about a year?

Or would you recommend treating for the purpose of consumption.


If Water Storage Conditions Are Right

If I was confident that I had cleaned and disinfected the BPA 55 gallon barrel ahead of time,


If I was confident that the water source was not contaminated (municipal water typically purified with at least 1ppm chlorine) – use swimming pool chlorine test kit to check this,


If I was confident that the barrel had remained sealed through the time period,

I would not be terribly worried about contamination after one year.

Heat, Sun, Algae Growth?

One potential concern in the example above is the heat. This might speed the rate of algae growth. But only if there were microorganisms in there to begin with that were not eliminated due to not enough chlorine (for example).

If it were me, I would initially boost the chlorine level to ~ 3ppm.

Water-Bleach Ratio for Drinking Water Purification

Algae also likes sunlight. If the water storage container is opaque (e.g. the dark blue color), this reduces photosynthesis.

The person did not say whether or not the containers were in direct sunlight. I would advise to shade them in some way.

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