What’s the Best Substitute for Distilled Water? (5 Options)

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Distilled water is a type of water that has been purified with a process called distillation.

If you can’t get your hands on distilled water for a specific purpose, you might be wondering what water types are most similar, suitable, or even better to use in its place.

Here, we’ve discussed our 5 top recommended substitutes for distilled water.

📌 Key Takeaways:

  • RO water, filtered tap water, deionized water, spring water, and boiled water are all good substitutes for distilled water.
  • Different distilled water substitutes are best suited to different applications. For instance, spring water and filtered tap water are good alternatives for drinking, but they’re not suitable for use in a CPAP machine or a humidifier.

⚗️ What Is Distilled Water?

It’s important to be clear on exactly what distilled water is before you start looking for alternatives.

Distilled water is purified water that has been treated with the distillation process.

During this process, water is boiled until it evaporates. The water vapor is funneled into a cooling corridor, which causes it to condense back into liquid form, where it collects in a separate chamber.

All the water’s impurities, including chemical pollutants, metals, mineral ions, and other dissolved solids, remain behind in the boiling chamber. The end result is water in its purest form.

Pouring distilled water out of a glass container

🔎 5 Best Alternatives To Distilled Water

Here are the 5 best alternatives to distilled water for various use cases.

Most Similar: Reverse Osmosis Water

If you’re looking for the most similar substitute for distilled water, reverse osmosis water can’t be beaten.

Reverse osmosis is a membrane separation process that sends water through a semi-permeable membrane with tiny pores. The majority of impurities in water are too large to pass through the pores and are rejected by the membrane. These impurities are then drained out of the system with a small amount of wastewater.

Reverse osmosis water is free from up to 99.99% of all total dissolved solids. The only contaminants that an RO membrane struggles to remove are dissolved gases, like some VOCs (which may not be present in the water source anyway).

Because reverse osmosis water is purified water, like distilled water, you can use it as a distilled water substitute in any situation that calls for pure water. For instance, you could use RO water:

  • In a CPAP machine
  • In a car battery (as long as the TDS reading is 5 PPM or lower)
  • In steam irons
  • In a fish tank
  • In any other situation where distilled or purified water is required

You can make your own reverse osmosis water at home with an under-sink or countertop reverse osmosis system. Or, you can buy bottled RO water. Just keep in mind that many bottled water products that have been treated with reverse osmosis have minerals re-added, which may make the water unusable for some uses.

Reverse osmosis dispensing unit

Best Mineral-Free: Deionized Water

If you just need water that’s free of minerals, the best substitute for distilled water is deionized water.

Deionized water has been treated in a water deionization system, which sends water through two separate resins – a positively-charged resin and a negatively-charged resin. These remove positively- and negatively-charged mineral ions from the water.

The water deionization process removes impurities including minerals, salts, organic material, and carbon dioxide. Some water deionizers are paired with water filtration systems to remove other contaminants like chemicals and metals, but this isn’t guaranteed.

We think deionized or demineralized water is best as an alternative to distilled water if you need mineral-free water for cleaning. While there’s no guarantee that deionized water is free from chemicals and other pollutants, it won’t form mineral deposits or scale on surfaces. So, it’s suitable for use in situations that require water with a lack of minerals.

You could also use deionized water in place of distilled water in CPAP machines and steam irons, although purified RO water is still better for this purpose.

Continue Reading: Distilled vs Deionized Water: A Comprehensive Analysis

Best For Drinking: Filtered Tap Water

In our opinion, filtered tap water is the best alternative to distilled water for drinking.

Filtered water is tap water that has been treated in a water filtration system. There are numerous different water filters that you can use at home, including:

  • Water filter pitchers
  • Under-sink water filters
  • Reverse osmosis systems
  • Countertop water filters

The type of filter you buy determines the contaminants you can remove from your water.

Some water filters with basic carbon filtration media can reduce chlorine, pesticides, and several other contaminants commonly found in municipal tap water.

Others combine a blend of filter media, including carbon, ion exchange, sediment filtration, and ceramic filter media. These offer a much more capable performance, removing hundreds of contaminants, including chemicals, heavy metals, PFOA/PFOS, pharmaceuticals, VOCs, pesticides, and herbicides.

The great thing about filtering your water at home is that you can choose a method that removes all the bad stuff while retaining healthy minerals. So, unlike distilled water, filtered water is contaminant-free but still has the taste and health benefits of natural minerals.

Cloud RO replacement filters in box

Also Great For Drinking: Spring Water

We think spring water is another great substitute for distilled water for drinking. Spring water is sold in bottles, so it’s not as cost-effective, or environmentally friendly as filtered water at home, but it’s a convenient solution for when you’re out and about and don’t have access to any other water source.

Spring water is sourced from a natural spring. Unlike distilled water, spring water isn’t free from all impurities. However, many spring waters are naturally filtered because they’re sourced from underground locations and have traveled through layers and layers of rock before reaching the surface.

Most bottled spring water products are naturally high in minerals like calcium, magnesium, and potassium, while being low in pollutants and contaminants.

Spring water is a great alternative to distilled water for drinking on the go because its rich mineral content gives it a pleasant taste, and your drinking habits contribute to your RDI for numerous minerals.

Best Microorganism-Free: Boiled Water

Distilled water is guaranteed to be free from microorganisms because distilling water involves boiling, which kills pathogens like bacteria and viruses.

If you just need a quick way to obtain water that’s safe from microorganisms, boiling water is a quicker and easier substitute for distilled water.

Boiling water to kill pathogens involves heating water until it reaches boiling point, then keeping it at a rolling boil for at least 2 minutes.

It’s much quicker to boil water than to make your own distilled water, which involves boiling water in a pot with the pot’s lid upside down, which catches the water vapor, and placing a glass bowl in the pot for distilled water to collect. This process takes hours, and isn’t necessary if you just need to kill microorganisms.

So, boiled water can be used instead of distilled water if your main priority is to drink water that’s safe from disease-causing pathogens. However, boiled water still contains impurities, so it’s not high-purity like distilled water.

Boiling water

📑 Final Word

Whether you usually drink distilled water or you use it instead of tap water for a specific purpose, there should be a suitable distilled water substitute for you.

Regardless of the water type, treating your water at home is more cost-effective in the long run than buying the water in bottles. So, if you’re interested in distilled water substitutes that you can use as long-term solutions, we recommend investing in your own at-home water treatment system.

You can buy RO systems, water distillers, deionizers, and other water filter systems to treat your tap water whenever required, eliminating the expense and plastic waste associated with bottled water.


What’s the best substitute for distilled water in a CPAP machine?

RO water and DI water are the best substitutes for distilled water in a CPAP machine. Both of these water types are mineral-free, so they won’t damage your CPAP machine or shorten its lifespan. RO water is better than DI water because it’s also free from other impurities (chemicals, metals, and other trace contaminants found in tap water), so it’s healthier for you.

What can I use instead of distilled water for my humidifier?

RO water is the best water to use instead of distilled water in a humidifier. Like distilled water, RO water is free from virtually all impurities. The only difference is that this water is purified with a membrane separation process, while distilled water is purified with the distillation process.

What’s the best substitute for distilled water in a car battery?

You can use RO purified water in place of distilled water in a car battery because both of these water types are pure and contaminant-free. Make sure your RO water has less than 5 PPM of total dissolved solids (TDS) to make it fit for this purpose.

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

If you don’t have distilled water, you can use various other types, including mineral water, filtered tap water, RO water, or deionized water. It depends on your required use of the water, and what type of water is recommended for this purpose.

What water is similar to distilled water?

Reverse osmosis water is the most similar to distilled water because it has had all its impurities, including chemicals, metals, and mineral ions, removed. Demineralized water is similar to distilled water because it’s free from minerals, but it’s not guaranteed to be pure.

Is boiled water the same as distilled?

No, boiled water isn’t the same as distilled. Boiling water will only kill microorganisms and cause chlorine to evaporate out of the water. It won’t remove impurities, like chemicals and metals. Distillation has an extra stage of the process that carries the vaporized water to a separate container, leaving the impurities behind in the boiling chamber.

  • Brian Campbell
    President & CEO, CWS, CWR

    Brian Campbell, a WQA Certified Water Specialist (CWS) and Certified Water Treatment Representative (CWR) with 5+ years of experience, helps homeowners navigate the world of water treatment. After honing his skills at Hach Company, he founded his business to empower homeowners with the knowledge and tools to achieve safe, healthy water. Brian's tested countless devices, from simple pitchers to complex systems, helping his readers find the perfect fit for their unique needs.

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