What can I use if I don't have distilled water?

While distilled water is the gold standard for purity, not having it doesn't have to stall your plans. In fact, many common household uses for this water have viable alternatives. So, what can I use if I don't have distilled water?

Quick Summary

Several alternatives to distilled water exist, though the best choice depends on the specific application. For sensitive devices like CPAP machines, purified or reverse osmosis (RO) water can be a temporary substitute, but making your own distilled water at home is a reliable option for maximum purity. For less critical needs like houseplants, even filtered tap water can suffice.

Key Points

• DIY Distillation: Easily make your own distilled water at home using a pot, a bowl, and ice to handle immediate needs.

• Know Your Application: The best alternative depends on the use; sensitive equipment like CPAP machines requires purer water than watering plants.

• Reverse Osmosis (RO) as an Alternative: For many applications, including short-term CPAP use, RO water is a close substitute for distilled water.

• What to Avoid: Never use tap water in sensitive appliances like humidifiers or steam irons due to mineral buildup.

• Filtered Water for Everyday: For less critical needs like drinking or general cleaning, filtered water is often sufficient and more mineral-rich than distilled.

Understanding the Need for Distilled Water

Distilled water is produced by boiling water into a vapor and then condensing it back into a liquid. This process effectively removes nearly all impurities, minerals, and other dissolved solids. Its purity is essential for specific applications, especially those involving delicate machinery or scientific processes where mineral buildup could cause damage or contamination. However, many people often use it out of habit or misconception, leading to unnecessary frustration when they can't find a bottle.

Making Your Own Distilled Water at Home

One of the most reliable and accessible alternatives is to make your own. The process is straightforward, requires only basic kitchen equipment, and guarantees water with a very high purity level.

Simple Stove-Top Distillation Method

1. Fill a large pot with tap water, about halfway. Place a smaller, empty glass bowl inside the pot, ensuring it floats and does not touch the bottom.
2. Invert the pot's lid and place it on top. Add ice cubes to the top of the inverted lid. The cold ice will help with condensation.
3. Gently bring the water to a simmer. As the water boils, it will create steam that rises and condenses on the cold, inverted lid. The distilled water will then drip down into the small bowl.
4. Continue the process, replenishing the ice as it melts. Never let the pot boil dry. Once you have a sufficient amount, carefully remove the lid and bowl to collect your pure, homemade distilled water.

Alternatives for Specific Household Uses

The most suitable substitute depends entirely on the application. A one-size-fits-all solution does not exist, and understanding the nuances is key to avoiding issues.

For CPAP Machines and Humidifiers

• Purified or Reverse Osmosis (RO) Water: While most manufacturers explicitly recommend distilled water to prevent mineral buildup and bacterial growth, purified or RO water is the next best option for short-term use. Be aware that these still may contain trace minerals, so more frequent cleaning of the humidifier chamber is crucial. Never use tap water long-term, as it will cause scale buildup and damage your machine over time.
• Temporary Solutions: In a pinch, for a single night, using bottled spring or tap water will not destroy your machine, but it should not become a regular habit. Clean the chamber thoroughly the next day.

For Irons and Steamers

• Purified Water: Standard purified water from a bottle is a suitable substitute. It has had many impurities removed and will be less likely to cause mineral scaling inside your appliance compared to tap water.
• Filtered Water: If your tap water is not excessively hard, filtered water from a pitcher can be a temporary solution. However, over time, some mineral deposits may still accumulate. It is essential to flush the appliance with vinegar and water if you notice any buildup.

For Plants and Aquariums

• Rainwater: Nature's own distilled water, rainwater is an excellent choice for sensitive houseplants like orchids and carnivorous plants that suffer from mineral buildup in tap water. Simply collect it during a storm.
• Filtered or Reverse Osmosis (RO) Water: For many common houseplants, filtered water is sufficient. RO water is a near-perfect substitute, as it has a very low total dissolved solids (TDS) count, mimicking the purity of distilled water. Hardy plants often do just fine with tap water.

For Cleaning and Laboratories

• Deionized Water: In laboratories and industrial settings, deionized (DI) water is often used instead of distilled water. It has been processed to remove ions and minerals, achieving a high degree of purity. You can purchase this from hardware stores or scientific supply outlets.
• Boiled and Cooled Water: For simple cleaning tasks that don't require absolute mineral-free water, boiling tap water can kill some microorganisms, though it does not remove mineral content. This is sufficient for applications like cleaning contact lens cases or other items that need disinfection, but not for lens-rinsing itself.

What Not to Use

It is just as important to know what not to use as it is to know what works. Choosing the wrong type of water can damage equipment or pose health risks.

• Tap Water (in sensitive equipment): The mineral and chemical content in tap water is the primary reason distilled water is needed. Using it in things like CPAP machines will lead to costly repairs.
• Spring Water: Marketed for its mineral content, spring water is the opposite of what's needed for applications requiring purity. The very minerals that give it flavor will cause scale.
• Boiled Water (for mineral-sensitive applications): While boiling kills germs, it concentrates minerals rather than removing them, making it a poor choice for irons or CPAP machines.

Comparison of Water Types and Their Uses

Water Type	Main Characteristics	Best for...	Not Recommended for...
Distilled Water	Ultra-pure, no minerals	CPAP machines, medical devices, steam irons, aquariums	Drinking (lacks minerals), cost-sensitive uses
Purified Water	Low dissolved solids, various methods	Short-term CPAP use, bottled drinking, general household	Long-term use in ultra-sensitive equipment
Reverse Osmosis (RO)	Low dissolved solids via membrane	Short-term CPAP use, plants, aquariums, drinking	Applications needing high mineral content
Filtered Water	Removes taste/odor, some contaminants	Everyday drinking, cooking, some hardy plants	CPAP machines, steam irons, sensitive devices
Boiled Water	Microorganisms killed, minerals remain	Simple disinfection, drinking once cooled	Mineral-sensitive equipment, long-term use
Tap Water	Varies widely, contains minerals	General washing, cooking where taste is not an issue	CPAP machines, irons, sensitive plants

Final Recommendations and Long-Term Solutions

For those who frequently find themselves without distilled water, investing in a home purification system may be beneficial. A reverse osmosis system provides a consistent, high-quality water supply for various needs. For occasional use, the DIY distillation method is cost-effective and reliable. The key is always to match the water's purity to the specific task at hand to protect your health and your appliances.

For more information on water quality and its impact on household items, consult the Environmental Protection Agency (EPA) or check out guides from reputable water filtration companies. Understanding the differences between water types empowers you to make informed decisions and find the right alternative when distilled water isn't available.

Conclusion

Not having distilled water is a solvable problem with multiple valid alternatives depending on your needs. For critical applications like medical devices, making your own distilled water or using reverse osmosis water is the safest bet. For more general purposes, alternatives like filtered water or even clean rainwater can be a suitable substitute. By understanding the basics of water purity and the intended use, you can confidently address your needs without relying solely on a store-bought solution.

Frequently Asked Questions

Is purified water the same as distilled water?

No, while both are treated, the methods differ. Purified water is often treated with multiple filtration methods to remove contaminants but may retain some minerals, whereas distilled water is boiled and re-condensed, removing nearly all minerals and impurities.

Can I use bottled water instead of distilled water?

Only if the bottle specifically says "distilled." Most bottled spring or drinking water contains minerals that can damage appliances requiring mineral-free water.

What happens if I use tap water in a CPAP machine?

Using tap water in a CPAP machine's humidifier will cause mineral buildup, or scale, in the chamber over time. This can harbor bacteria, damage the heating element, and shorten the lifespan of your machine. It should only be used as a last resort for a single night.

Can I boil tap water to make it distilled?

Boiling tap water will kill bacteria and other microorganisms but will not remove minerals. In fact, it concentrates them as some water evaporates. To get distilled water, you must collect the steam that condenses after boiling.

Is rainwater a good substitute for distilled water?

Rainwater is naturally distilled and is an excellent option for sensitive houseplants and aquariums. However, it should be collected cleanly and may not be suitable for medical devices.

Is drinking distilled water safe?

Yes, it is safe to drink distilled water occasionally. However, for long-term consumption, it is not ideal because it lacks the beneficial minerals, such as calcium and magnesium, found in tap or filtered water.

Where can I buy deionized or reverse osmosis water?

Deionized water can often be found at hardware stores or automotive supply shops, as it is used in car batteries. Reverse osmosis water is available at many grocery stores with bulk water dispensing machines.