Distilled water and pure water are often used interchangeably, but there are some key differences between the two. In this article, we’ll explore what distilled water and pure water are, how they’re made, their uses, and whether distilled water really is just pure water or not.
What is Distilled Water?
Distilled water is water that has been boiled and condensed to remove impurities. The process works like this:
- Water is boiled, turning it into steam.
- The steam is cooled and condensed back into liquid water, leaving behind solid impurities.
- The condensed liquid water is collected, now free of dissolved solids, salts, metals, and other contaminants.
So in essence, distilled water is water that has been purified via a process of distillation. This process removes nearly all minerals, ions, particles, and pollutants from the original water source.
How is Distilled Water Made?
There are a few different ways to make distilled water:
- Boiling: Water is boiled in a pot and the steam is captured and cooled in a coiled tube. The condensed liquid is collected.
- Steam distillation: Water is boiled in a still and the steam piped away and condensed. This method is used commercially.
- Fractional distillation: Water is turned into vapor and separated by boiling point. Only the pure vapor is collected.
- Reverse osmosis: Water is forced through a semipermeable membrane that filters out contaminants.
No matter the method, the goal is to evaporate pure water and condense it again, leaving behind anything that was dissolved in the original water source.
Properties of Distilled Water
Here are some key properties of distilled water:
- It is pure H2O with no dissolved minerals or salts.
- It has a neutral pH of around 7.
- It has very low amounts of total dissolved solids (TDS).
- It does not conduct electricity well due to lack of ions.
- It has a flat, neutral taste.
- It freezes at 0°C and boils at 100°C.
Uses of Distilled Water
Because of its high purity levels, distilled water has a variety of uses including:
- Medical, laboratory, and scientific applications where high purity water is required.
- Batteries, cooling systems, and appliances where mineral buildup needs to be avoided.
- Auto radiators, irons, humidifiers, and aquariums.
- Home drinking water to remove potential contaminants.
What is Pure Water?
The term “pure water” has no standard scientific definition. However, it generally refers to water that is completely free of contaminants, pollution, and dissolved solids. The key word is “pure.”
While there are no impurities allowed in pure water, it does contain:
- Two hydrogen atoms
- One oxygen atom
That’s it – just H2O with nothing else added or taken away. Pure water is simpler than rainwater or distilled water, which still contain small amounts of minerals and dissolved gases respectively.
Creating Pure Water
Creating 100% pure H2O water is difficult:
- Boiling gets close but small amounts of solutes remain.
- Reverse osmosis filters water but some molecules get through.
- Ion exchange resins swap ions but don’t remove uncharged solutes.
To get completely pure water, more advanced techniques must be used:
- Deionization – Uses resins to remove ionic solutes by swapping hydrogen and hydroxide ions for other ions.
- Distillation – Water is evaporated and condensed as pure H2O vapor.
- Electrodialysis – Ions are pulled from water through selective membranes by electric current.
Of these methods, distillation produces the purest water possible by completely converting water to vapor and back. The result is 100% H2O.
Properties of Pure Water
Here are some properties of hypothetically 100% pure H2O:
- No impurities, minerals, salts, metals, or pollutants
- Neutral pH around 7.0
- Extremely low conductivity and ion concentration
- Boiling point of 100°C and freezing point of 0°C
- Density of 1.0 g/mL and viscosity of 0.89 cP at 20°C
- Completely clear with no color, smell, or taste
However, perfectly pure water does not exist naturally. There are always trace amounts of ions and gases dissolved in natural water supplies.
Uses of Pure Water
Ultrapure, laboratory-grade water has applications including:
- High precision scientific experiments and measurements.
- Electronics and semiconductor manufacturing.
- Pharmaceutical processing.
- Laboratory tests that require blank controls.
Most everyday uses do not require water of this purity level. Drinking ultrapure water could even be harmful long-term since it lacks minerals.
Similarities Between Distilled and Pure Water
There are some important similarities between distilled water and pure water:
- Both have been purified to remove contaminants like minerals and salts.
- Neither has any color, smell, or taste when pure.
- They freeze at 0°C and boil at 100°C.
- They have neutral pH levels around 7.
- They have low conductivity and ion concentrations.
- They consist only of hydrogen and oxygen atoms (H2O).
In many practical applications, distilled water and pure water can often be used interchangeably. Their degree of purity is higher than tap or bottled water.
Differences Between Distilled and Pure Water
However, there are some subtle differences between distilled and pure water:
| Distilled Water | Pure Water |
|---|---|
| Contains almost zero impurities | Contains absolutely zero impurities |
| Typically contains dissolved atmospheric gases like oxygen | Contains no dissolved gases |
| Has trace amounts of minerals and ions | Has no minerals or ions at all |
| Electrical conductivity around 0.5-3 μS/cm | Extremely low conductivity close to 0 μS/cm |
| Made by methods like distillation and reverse osmosis | Requires advanced purification like deionization |
| Used for drinking, automotive, and household uses | Used for specialized laboratory applications |
So while distilled water is very pure, it is not quite at the level of 100% purified H2O. Tiny amounts of gases and solutes remain after the distillation process. Pure water has been purified to a higher degree.
Is Distilled Water Considered Pure?
Based on the above differences, distilled water is generally not considered to be as pure as theoretically possible pure H2O. However, it’s purity is very close.
For most applications outside of scientific laboratories, the tiny levels of impurities in distilled water do not matter. So distilled water can be safely used anywhere highly purified water is required.
Is Distilled Water Safe to Drink?
Drinking distilled water is generally safe because of its very high purity levels. However, there is some debate around whether it is the healthiest type of water to drink regularly. Here are some pros and cons:
Pros of Drinking Distilled Water
- Removes potential contaminants and toxins found in tap and bottled water
- May help flush toxins and aid in detoxification
- Unlikely to cause mineral overdose
- No unpleasant taste, smell, or color
- Low risk of transmitting water-based diseases
Cons of Drinking Distilled Water
- Lacks essential minerals found in natural drinking water
- May lead to mineral deficiencies long-term
- Could potentially leach minerals from the body
- Has flat, tasteless flavor
- Not recommended for infants or those on fluid-restricted diets
Most leading health organizations consider distilled water safe to drink but do not recommend it as a primary source of daily drinking water. They typically recommend drinking distilled water only on a temporary basis or mixing it with mineral water.
Is Distilled Water Safe for Baby Formula?
Most pediatricians recommend against using distilled water for baby formula or as a primary water source for infants. Since distilled water is stripped of minerals, it does not provide the electrolytes and nutrients that babies require. Low-mineral spring water or purified tap water are safer options.
Conclusion
In summary, distilled water is water that has been purified through distillation to remove nearly all impurities. Pure water refers to hypothetical 100% H2O with nothing else present. While not identical, distilled and pure water share many similar physical, chemical, and sensory attributes.
Distilled water can function as pure water for applications like scientific experiments and laboratories. However, due to trace levels of dissolved gases and minerals, distilled water does not quite reach the theoretical purity of 100% H2O.
Drinking distilled water is generally considered safe, though it lacks beneficial minerals. Using distilled water solely long-term could lead to mineral deficiencies. But overall, distilled water is still one of the purest forms of water available.