Does Distilled Water Go Bad?

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You may have distilled water in your home to use in appliances or drink it if you don’t have access to other clean water. Either way, you may wonder how long you can keep distilled water before it becomes unusable and how you should be storing it. Does distilled water go bad?

Distilled water, being free of both impurities and minerals, does not go bad if packaged and stored correctly. However, if the water is exposed to contaminants, the purity of the water will be affected. While the water may still be suitable for household uses, it will no longer be safe to drink.

Being so pure, distilled water is unlikely to spoil for years if you keep it sealed and stored appropriately. However, once opened, there is a possibility of spoilage that will mean the water is no longer fit for drinking.

Can Distilled Water Go Bad?

water glass and jug

Distilled water will only go bad if exposed to environmental pollutants, which can happen if it is left open, exposed to chemicals, or in the sun. Correctly stored, distilled water can last for years.

To understand why it is unlikely for distilled water to go rancid and why you need to store it properly, it is essential to know what distilled water is and how to use it.

What Is Distilled Water?

Distilled water is ordinary tap water that has gone through the process of distillation to remove impurities and mineral content from the water.

The process of distillation involves boiling water to make it produce steam. Cooling the steam makes it condense or turn back into liquid form. We call the resulting condensed liquid distilled water. 

Distilling water removes any contaminants or impurities in the water. Unfortunately, the distillation process also eliminates any mineral content occurring naturally in regular tap water, bottled water, spring water, or mineral water.

Distilled water therefore has a flat or bland taste, with no flavor.

How Does Distilled Water Go Bad?

If distilled water has had all impurities removed, how is it possible that it goes bad? Any water can go bad if exposed to a contaminant, like chemicals or bacteria. Exposing distilled water to pollutants means that there is a chance that it may be contaminated.

So long as your distilled water remains unopened, there is minimal opportunity for bacteria to develop, especially since the water is purified.

However, if you open the water and leave it open for any time, you make contamination possible — no lid or seal means that dust, chemicals, and bacteria can enter the water. 

It is still improbable that the water will develop bacteria as distilled water, stripped of all impurities and minerals, is an unsuitable environment for bacteria to thrive.

Uses Of Distilled Water

There are two main reasons to keep distilled water. How you plan to use the water will influence how you store it and how long you can keep it.

For Household

You can use distilled water for household appliances, such as steam irons, or to refill the electrolytes in a vehicle battery. Distilled water is helpful as it will not corrode mechanical parts of equipment or motors.

You can buy distilled water for use at home and in the garage from most stores.

For Drinking

If you don’t have access to clean drinking water, or if your water supply has been contaminated, you may need to rely on distilled water for drinking.

In this case, it is more likely to have purpose-designed steam distilling equipment to produce water that is drinking quality. However, you can also drink store-bought distilled water if you have no other option.

Unless you have no other suitable water available, it’s not a good idea to drink distilled water because although it contains no toxins, it also has no mineral content. Water usually contains minerals like sodium, magnesium, and calcium that are necessary for good health.

If you do rely on distilled water as your primary source of drinking water, make sure that you get the necessary minerals from other sources (such as food or supplements). Your body needs these elements not to develop a mineral deficiency and ensure that your body stays hydrated with the correct balance of electrolytes.

Distilled water is also not tasty to drink as it is completely flavorless.

Drinking distilled water once in a while, if you are thirsty, is harmless.

How Long Can You Keep Distilled Water?

If stored in a cool, dark area, unopened, sealed, correctly packaged distilled water will last three to five years.

However, how long you store your distilled water will depend on where it comes from and how you plan to use it. 

For Household

Most distilled water will come with a label indicating the expiry date. However, you can keep distilled water for households use almost indefinitely if it is unopened and stored correctly.

For best results, keep the water for three to five years after the production date so long as it is unopened.

Once the seal is broken, distilled water will last for nine months to a year if kept refrigerated. Out of the fridge, the water will start going bad after about seven days. 

For Drinking

If you plan to drink the distilled water, treat it like regular bottled water, paying attention to the best-before date. If sealed, you can keep the water beyond this date as it will not expire for years unless opened. Once opened, you need to drink the water within a couple of days to a week.

You should distil a fresh batch every few days if you are making distilled water at home using distillation equipment. The water is unlikely to become contaminated if kept in the fridge, but it will become stale.

Signs That Distilled Water Has Gone Bad

Because distilled water is so highly purified, it is unlikely that you will see or taste any contaminants. 

Even if you’ve left your distilled water standing open for a couple of hours, that water is still cleaner than most regular tap water and even bottled water. It will still be perfect for household uses and most likely for drinking as well.

However, if you have opened your distilled water, or stored it in plastic, in direct sunlight, or near chemicals, there may be some indications that it has gone off.

Algae

You will know immediately that your distilled water has gone bad if you can see blue or green algae. Algae appear on the inner sides of the bottle, as scum floating on the water or even as sediment. Discard the water immediately and sterilize the container.

Algae will develop in any water left open to bacteria and sunlight as they are attracted to warm environments. It is unusual for algae to form in distilled water as there are no nutrients, but it is possible if your water has not been stored correctly for an extended period.

Cloudiness

Another noticeable sign of contamination is that the water is no longer clear but cloudy. Cloudiness suggests that there is chemical or bacterial contamination.

You can still use cloudy distilled water for household applications at a push, but you should never drink it.

Preferably discard any distilled water that is cloudy and sterilize the container. 

Smell

If you open your distilled water and encounter a sour or unpleasant smell, discard it.

However, ensure that the water is the problem, not the container. Pour a small amount of water into a glass and smell it.

The cause of a strange smell is often storing water near a chemical or solvent, which has affected the water.

Again, you can use water with a slight chemical smell for household equipment, but do not drink it.

Instead, get rid of the water and sterilize the container.

Chemical Taste

Distilled water should have no flavor whatsoever, so if you can taste it, especially if it has a chemical taste, it has been contaminated somehow.

The most likely cause of a chemical taste is storing water in a plastic container in sunlight, causing the chemicals in the plastic to leach into the water. Another reason is storing water alongside strong-smelling chemicals or solvents.

Do not drink this distilled water or use it for any purpose. Discard the water and the container.

What Happens If You Use Contaminated Distilled Water?

There are unlikely to be any serious consequences if you use slightly contaminated distilled water in your steam iron. However, never use water that has algae growing in it, or you may damage your appliance, equipment, or vehicle.

What Happens If You Drink Contaminated Water?

Drinking contaminated water carries serious health risks, whether chemicals, algae, or bacteria have contaminated the water. Never drink distilled water that is past its use-by date.

According to the USFDA, most waterborne illnesses will manifest within 20 minutes to a day of consuming the contaminated water. However, a waterborne disease can appear as long as six weeks after drinking contaminated water, especially if you are regularly drinking chemically contaminated water.

If you do drink any water that you think may be past its best, look out for these symptoms:

  • skin discoloration
  • vomiting
  • diarrhea
  • stomach pain
  • fever
  • headache

Waterborne food poisoning is dangerous and can impact your long-term health, while waterborne diseases are potentially fatal. Consuming chemically contaminated water over the long term can increase the risk of cancer and kidney failure.

Contact your local doctor or hospital immediately if you think contaminated water has made you ill.

How To Store Distilled Water To Prevent It From Going Bad?

Because distilled water contains no impurities, it will last for years and remain pure so long as you store it correctly and keep it safe from pollutants.

No matter the purpose of your distilled water, observe these storage guidelines:

  • Keep the water sealed until you need to use it. Once opened, ensure that the container is sealed as tightly as possible.
  • Always keep it in a clean container away from direct sunlight. Sunlight can cause plastic leaching and encourage bacterial growth.
  • Store the water in glass or high-density polyethylene (HDPE) containers to prevent chemicals from leaching into the water. HDPE containers specifically avoid rust and protect the water from exposure to light and heat. They are also impact-resistant.
  • If you are storing vast amounts of drinking water, ensure that the containers are food-grade.

For Household

  • You can store distilled water for household use for years, so long as you keep it sealed and in a cool, dark storage area.
  • Avoid storing the water near chemicals or solvents that could leach into the water: keep distilled water away from dry-cleaning fluids, household cleaners, gasoline, and paint thinners.
  • Keep opened water in the fridge, airtight.
  • Store distilled water in glass or HDPE containers long-term, although plastic containers are suitable for short-term storage in the fridge.

For Drinking

  • Keep store-bought distilled water sealed in a dark cupboard or pantry, away from household cleaners, paint, or other chemicals.
  • Once opened, keep the water in an airtight container in the fridge.
  • Distilled water made at home using distillation equipment has a shorter shelf life. If the distiller comes with a glass tank, that is ideal. 
  • Otherwise, store home-distilled water in an airtight glass or BPA-free food-grade container in the fridge and consume within three to seven days.

So, Does Distilled Water Go Bad?

Although it is unlikely, distilled water can go bad if stored incorrectly. Leaving distilled water open, unsealed, in plastic containers, and sunlight can lead to contamination by chemicals and bacteria. While it is safe to use old distilled water for household applications, it is dangerous to drink contaminated distilled water. Always store distilled water in glass or HDPE containers in a dark, cool place, away from sunlight and chemicals.

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