distilled water safety feat

How long does distilled water last? Can it go bad?

All the options available for something as basic as water would have been unthinkable a few decades ago: from tap water, to spring water, mineral water, etc. the supermarket shelves offer us a wide range of options. Among these, distilled water appears to be one of the most versatile and yet most controversial, and whether it should be drank or not it’s still wildly debated.

Despite its unusual taste, sportsmen even encourage people to drink distilled water because its lack of sodium helps improving health and preventing fluid retention. Some people still prefer to only use it for common everyday tasks such as watering plants, or for steam irons and aquariums.

From the unusual process to its many uses, the trend of distilled water affirms itself every day and so the question arises, if you do have some distilled water can it go bad? How long can you use it for? Can you still use it if it’s out of date? Read this article to find answers to some of these questions.


How Is Distilled Water Made?


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Distillation is a very ancient practice and one of the most popular processes to purify water, one of many options along with filtration, reverse osmosis, deionization and others.

The process consists of turning water into vapor and later condensing that vapor back into liquid form in a different container. Said process allows all the impurities to be left behind during the evaporation step. This will remove not only microbes but also harmless minerals such as magnesium and calcium, leaving the water in its purest form (essentially H2O).

Due to the declining quality of tap water, distilling water for drinking purposes has become more and more common practice. Some even started distilling water at home.


Can distilled water go bad?


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See also
How Long Does Apple Juice Last? Can It Go Bad?

No matter how often you use distilled water and what you buy it for, at some point you probably wondered whether that leftover gallon in the pantry can still be utile or if it should be thrown away. If you distill water yourself at home using a steam stiller, you have probably considered storing it for emergencies.

Distilled water can’t go bad on its own, but packaging and the outside environment can affect the water’s qualities and have an impact on how long it will last.

Due to the distillation process, distilled water is susceptible to absorbing carbon dioxide from the air, increasing its acidity levels. It can also absorb impurities from the container it’s stored in.



How to store distilled water?


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Distilled water should be kept in a cool place away from direct sunlight and when opened it should be immediately closed again until further usage is required. It’s important to seal the water tight, to prevent any dust or other impurities to contaminate it.

Small amounts of distilled water can be stored in glass bottles or glass tanks, but for larger quantities some experts recommend to use high-density polyethylene (HDPE) containers for storage.

HDPE containers create the ideal conditions for distilled water to last a long time. These containers are normally impact-resistant and corrosive proof, with limited light exposure and cool temperature control.

In case you are storing distilled water for home appliances, keep the product away from solvents and chemicals such as household detergents, dry cleaning chemicals, paint thinners and gasoline.

Like for many types of packaged food and beverage, a kitchen pantry or a cabinet will do just nicely to store unopened bottles of distilled water, but if you’re keeping some for your car’s engine be mindful not to leave it in your car, especially during the day.

Once you open a bottle of distilled water it can be stored both at room temperature or in the fridge, but, most important, remember to close the cap very tightly. Distilled water can also be frozen and used for ice cubes. Fun fact: ice cubes from distilled water are clearer due to their high purity level.


How long does distilled water last?

Just like plain water, store-bought distilled water will last indefinitely, provided that it’s sealed tightly, but it probably should be changed every few months. It can reach up to 3-5 years after the production date.

Each time air hits the distilled water its conductivity will increase over time and some contamination will occur, but it will be minimal compared to normal mineral water.

Although bottle water may last for years, storage conditions will impact the taste. Your choice of container to store your distilled water in will either prolong or deteriorate its shelf life. Plastic containers can seep unwanted chemicals into the water and rapidly undermine its quality.

When it comes to distilled water for home appliances it can last a few years when unopened, and another year or two after opening if you take good care of it.

If you make distilled water at home, it will probably last for a week or two. After that time it will still be safe to drink but it might start to smell stale. Also the quality of the distiller will also have a role in determining the quality of the home-made distilled water. If it starts to smell bad, better make a new batch.


How can you tell if distilled water has gone bad?  

If distilled water was stored properly, it should be fine, both for drinking purposes and use in home appliances. But after a few days of opening the bottle or distilling the water, it might start to slightly “smell” and taste stale. That is often due to the container, rather than the water itself.

If you notice that the smell or taste of the distilled water have changed significantly or find impurities, just discard the water. If it’s water for appliance use and looks and smells like usual, feel free to use it.

Commercially distilled water does not go bad very easily, since it has undergone a rigorous purification process and does not contain any nutrients for microbial growth. The occurrence of microbial contamination in distilled water is lower compared to other plain water.

A few days after opening, the distilled water might change in both taste and smell. If you notice a change in colour or any impurities (such as dust, or small animals) that may get into the bottle, it is best to discard the water.

If the storing container has been opened for a long time, you might notice green algae starting to grow inside and it should be thrown away.

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