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Can Distilled Water Ever Go Bad?

Quick Answer: Can Distilled Water Go Bad? Just like other water, distilled water doesn’t spoil or go bad over time if kept in adequate storage conditions. That’s great to know, but environmental factors including air pollutants can harm its purity.

These pollutants can get in during the packaging process hence the distilled water may not ever go bad on its own yet can end up becoming contaminated and unsafe for drinking. 

In this guide, we will look at whether distilled water can go bad, how it could go bad, and how you can detect that.

Can Distilled Water Ever Go Bad?

How To Detect That Distilled Water Has Actually Gone Bad

As distilled water has been purified, it will be without contaminants and minerals so it should taste bland.

If you’re left wondering if your distilled water has maybe gone bad, follow these tips to detect that without having to taste it.

Smell It

Open the distilled water container and smell the contents as it should not smell of anything at all.

If there is a smell then there is a strong possibility that the distilled water has indeed gone bad and is no longer pure.

This could be down to air pollutants or strong chemical smells in the surrounding environment. Sunlight exposure can also cause leaks in plastic bottles which creates a chemical taste in the water.

Even water can have an off smell and like other substances, including foodstuffs, if you’re put off by the smell, you should not consume it.

If you’re struggling to detect an odor from the water after opening the container, simply pour some into a bowl and get a better smell.

The distilled water should not smell of anything so if it does, and certainly if it has a bad odor, then it is time to empty the container and replace its contents with some fresh distilled water.

Cloudy Appearance

How the distilled water looks can also be a sign that it has actually gone bad. Just like the smell and taste, you should be able to detect much of anything.

Distilled water should be clean and have a clear appearance where you can see straight through it. If you’re using the distilled water for your home appliances then a cloudy appearance should not be a problem.

However, if you’re used to drinking distilled water then a cloudy appearance is a clear sign that you should not as chemicals and pathogens have resulted in contamination. 


Just as a cloudy appearance is a sign that distilled water has evidently gone bad, the appearance of green algae should be enough to make you empty the container.

These blue-green algae can form when any water that is rich in nutrients is left exposed to the sun.

Direct sunlight may not have minerals, or even nutrients, but leave the container open in direct sunlight and contaminants can still get in and then create algae.

Any blue-green colored floating algae, sediments, or scums will indicate an infestation of algae that should be quickly discarded.

How Long Distilled Water Should Last

How Long Distilled Water Should Last

You can be assured that distilled water should last pretty much indefinitely, as long as it is stored in tightly sealed containers.

If contaminants cannot get into the distilled water then it should be fine, pure, and ready to use.

You may see a best-before date on a bottle of distilled water yet this is typically a requirement that should not be strictly followed when it comes to water that has been distilled.

Keep the container stored properly and it will be fine to use well beyond that best-before date.

Adequate storage for a container of distilled water does not have to be complicated, or use any fancy equipment. Keep the clean container out of direct sunlight, such as in the fridge or pantry, and that will be fine.

For use in your home appliances, you can use distilled water for around two months and it will be great to use.

However, if you use distilled water for drinking then once the bottle is opened you should finish it in a week for a large bottle and inside a few days for a smaller one, ideally inside a week.

The shelf life of distilled water will largely depend on where it is stored and whether it has been opened or not. An opened bottle of distilled water should have a shelf life of between 9 and 12 months, if refrigerated.

If left in the pantry, you should only expect that opened bottle to have a shelf life of between 3 days and a week.

For an unopened bottle of distilled water, keeping it in the refrigerator should give it a shelf life of over two years.

Similarly, if the bottle of distilled water is kept out of direct sunlight and left in the pantry then it should also have a shelf life of over two years.

This is likely why you should buy distilled water in bulk if you have the space in your home.

With a shelf life of over two years, if kept out of direct sunlight and left unopened, you do not need to worry about it, whatever happens.

Frequently Asked Questions

How Should I Store Distilled Water?

If you can, store your distilled water so that it is away from any direct sunlight.

This is certainly the case if the distilled water is kept in a plastic bottle as the sunlight can disintegrate that plastic, causing chemicals to worryingly leak and contaminate the water.

Instead of plastic, you can use high density polyethylene (HDPE) tanks or drums for large quantities of distilled water.

The tanks or drums should be food grade quality too which should keep the distilled water stored securely for longer.

Why Should I Keep A Distilled Water Container Tightly Sealed?

The main reason for keeping a distilled water container tightly sealed is to keep out contaminants.

Distilled water can also pick up odors so if you do have a container in the garage, keep it sealed, or else the water could take on the smell of any paint or gasoline.

In a tightly sealed container, you can ensure that the distilled water remains pure for drinking and using in appliances.

Jess Smith