How does deionized water compare to tap water in terms of purity?
Deionized water has almost all dissolved mineral ions removed, so it is purer than tap water in mineral content. But ion exchange removes charged ions only; it does not significantly remove bacteria, viruses or uncharged organic molecules. Tap water comes from a utility that treats it for drinking, while deionized water is made for labs, batteries and cooling systems, not as a daily drink.
Free download
Juice, Soda and Water Storage Chart (PDF): How long juice, soda, coconut water and bottled water last, opened and unopened. 19 rows, each with its source.
Thank you
Your chart is ready
We use your email only for this download.Also free:
Home Bar Storage Chart (PDF)Milk and Dairy Storage Chart (PDF)Coffee, Tea and Hot Drinks Storage Chart (PDF)Drink Strength, Calories and Units Cheat Sheet (PDF)Want the full pack? About 10 printable sheets: a larger chart for each drink type, a “has it gone off?” checklist, date labels, a party planner and an inventory sheet.
In this article
What is deionized water?
Deionized (DI) water has been passed through ion exchange resins that capture charged particles such as calcium, magnesium and sodium. The result is water with very low mineral content. Producers often pre-treat it to remove larger particles and organic material first.
Is deionized water purer than tap water?
In one sense, yes: it has far fewer dissolved minerals. In another sense, no. Ion exchange targets ions, so by itself it does not significantly remove bacteria, viruses or uncharged organic molecules. Other steps such as reverse osmosis or UV treatment are used for that. Tap water, by contrast, comes from a utility that treats it for drinking.
| Tap water | Deionized water | |
|---|---|---|
| Dissolved minerals | Present, varies by area | Very low |
| Treated for drinking | Yes, in public systems | Not by the deionizing step alone |
| Taste | Varies | Flat or bland |
| Typical use | Drinking, cooking | Labs, electronics, batteries, coolant systems |
Is it safe to drink?
A producer guide says deionized water is generally safe to drink occasionally but is not recommended as a main source of hydration, since it tastes bland and lacks minerals. Most minerals in a normal diet come from food, but you gain nothing over tap water. If you have a medical condition or special water needs, ask a doctor.
When should you use it?
- Good for: laboratory work, pharmaceutical and electronics cleaning, car batteries and coolant systems, where minerals cause scale or interference.
- Not needed for: everyday drinking, coffee or tea.
Common mistake
Deionized water absorbs carbon dioxide from the air, which changes its pH and conductivity, so an opened container does not stay ultra-pure for long. Keep it airtight.
People also ask
Is deionized water the same as distilled water?
No. Deionized water has ions removed by resins; distilled water is boiled and the steam is condensed. They are made differently and are not interchangeable labels.
Can you drink deionized water every day?
It is not recommended as your main drinking water. It is bland and has no minerals, and tap water is already treated for drinking.
Why is deionized water used in batteries and coolant systems?
Without minerals it avoids scale and conductivity problems.
Sources
About · How we verify this · Editorial policy · Corrections
What would help you most next?
One tap. Anonymous. It helps us decide what to build.
Thank you. The free charts above are yours to keep.
