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


How long is stored water good for?

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.

Use A Water Filter

Pro Tip: If you are storing water for preparedness, then you really should have a Berkey Water Filter! This will insure a tremendous peace of mind while drinking that water (or any water).

Check out all of the Berkey models at their their U.S. authorized dealer:


Can Water Go Bad?

Many people are under the misconception that water can go “bad” over time.

The thing is… water is water is water.

Safe drinking is about the contaminants.

If the water is not contaminated to begin with,

and sealed in a clean non-contaminated environment,

and so long as there are no contaminants that enter the environment,

It will theoretically be safe forever.

Replace it every year?

Given the conditions mentioned (exposure to high temperatures during the summer months,) I would replace the water each year. It’s not that difficult to do for peace of mind.

IF there had been any organic contamination within the barrel, the heat from the summer months could increase the likelihood of bacteria/microorganisms growing. Especially if the chlorine level gets too low. Also, chlorine will break down with heat and sunlight.

Side Note: Chlorine (bleach) has a shelf life and will lose its potency over time. When it breaks down, it basically turns to a salt, so as a rule-of-thumb regarding your regular household bleach, I would replace it each year.

Another reason to replenish the stored water: The water will taste ‘flat’ over time. Though the flat taste can be somewhat remedied by pouring the water back and forth from one container to another to reintroduce more oxygen when its time to drink it (aerated).

Purify Water for Safety

IF you suspect for any reason that the water might be unsafe to drink, then by all means, purify it before drinking! The safest way is to boil it.

You can also purify water with ordinary ‘regular’ household bleach.

There are many ways to purify water to make it safe to drink,
including the methods mentioned here…

The Smallest Berkey Countertop water filter – Specs

Big Berkey