The pH of distilled water and tap water can vary significantly due to their preparation methods and the presence of contaminants. While distilled water typically has an acidic pH, ranging from 4 to 5.7, tap water generally has a more neutral pH, typically between 6.5 and 8.5. Understanding these differences is crucial for various applications, from drinking water to laboratory use.
Typical pH Range of Distilled Water vs Tap Water
Distilled Water
Distilled water is prepared by boiling and then condensing water vapor, which removes many impurities. However, this process can leave the water with a low pH due to the absorption of CO2 from the air. The pH of distilled water is typically acidic, ranging from 4 to 5.7.
Tap Water
Tap water, on the other hand, has a more neutral pH, typically ranging from 6.5 to 8.5. This is due to the presence of minerals and ions that help maintain a stable pH. Tap water is treated with various chemicals and processes to remove impurities and maintain a stable pH, including the addition of minerals and ions.
Preparation Methods and Contaminants
Distilled Water
The preparation of distilled water involves boiling and condensing water vapor, which removes many impurities. However, this process can leave the water with a low pH due to the absorption of CO2 from the air. Distilled water lacks ions, making it a poor conductor of electricity and prone to contamination by atmospheric CO2, which can lower its pH.
Tap Water
Tap water, in contrast, is treated with various chemicals and processes to remove impurities and maintain a stable pH. This treatment can include the addition of minerals and ions that help maintain a neutral pH. The presence of these minerals and ions helps to stabilize the pH of tap water.
Dealing with Contaminants and Balancing pH
Removal of CO2
Boiling distilled water can help remove CO2, which can raise the pH. However, this method is not always effective and may not completely eliminate the acidic nature of distilled water.
Adding Minerals
Adding small amounts of minerals like NaCl (sodium chloride) can help improve the conductivity of distilled water and make pH measurements more accurate.
Using pH-Buffering Substances
In some cases, adding pH-buffering substances like bicarbonate can help stabilize the pH of distilled water.
Helpful pH Quantity to Consume
Drinking Water
For drinking purposes, tap water with a pH between 6.5 and 8.5 is generally considered safe and healthy. Distilled water, due to its acidic nature, is not recommended for regular consumption.
Laboratory Use
In laboratory settings, distilled water is often used due to its purity. However, its low pH can affect certain experiments, and measures should be taken to stabilize the pH or use alternative methods.
History and Alternatives
Historical Use
Distilled water has been used for centuries in various applications, including laboratory experiments and medical treatments. Its low pH was not always a concern, as the focus was on its purity rather than its pH.
Alternatives
For applications where a neutral pH is required, alternatives like deionized water or RO (reverse osmosis) water can be used. These methods remove impurities while maintaining a more neutral pH.
References
- Reddit – Distilled water pH. (2023, September 11). Retrieved from https://www.reddit.com/r/chemistry/comments/16g727e/distilled_water_ph/
- Awesome Water Filters – pH of Distilled Water vs. Tap Water. (2022, July 16). Retrieved from https://www.awesomewaterfilters.com.au/blogs/news/ph-of-distilled-water-and-tap-water
- Byjus – What is the difference between common tap water and distilled water on pH scale?. Retrieved from https://byjus.com/question-answer/what-is-difference-betwee-common-tap-water-and-distilled-wayer-on-ph-scale/
- NCBI – The pH of water from various sources: an overview for recommendation for patients with atopic dermatitis. (2013, July 30). Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3736366/.