What is Pure Water?
In scientific terms, chemically pure water contains only hydrogen and oxygen molecules ($H_2O$), with virtually all other substances, including minerals and microbes, removed. This level of purity is typically achieved through intensive processes like distillation, deionization, or reverse osmosis.
The Purification Process
- Distillation: This method involves boiling water and then condensing the steam back into a liquid state, leaving most solid contaminants behind. It is one of the oldest and most effective purification methods for removing minerals and heavy metals.
- Reverse Osmosis (RO): RO uses pressure to force water through a semipermeable membrane, which filters out contaminants, dissolved solids, and other impurities. This is a very common method for creating bottled purified water.
- Deionization: Also known as demineralization, this process uses ion exchange resins to remove dissolved mineral salts from water. This results in highly pure water, but it doesn't remove non-ionic contaminants.
What is Tap Water?
Tap water is simply the water supplied to a home or building through a tap. It originates from surface water (rivers, lakes) or groundwater (aquifers). Before it reaches your home, it undergoes municipal treatment to make it safe for consumption. This typically involves filtration to remove large particles and disinfection, often using chlorine, to kill harmful microorganisms.
Municipal Treatment and Regulations
While treated to be potable, or safe to drink, tap water is not chemically pure. The final product contains residual levels of minerals, salts, and treatment chemicals, depending on the source and local regulations. For example, many municipal water systems add fluoride to aid dental health. The quality and taste of tap water can also vary significantly from one location to another due to differences in the source water and treatment methods.
Key Differences Between Pure and Tap Water
Beyond the presence of dissolved solids, several other factors differentiate pure water from tap water. These differences have implications for taste, use, and even health.
Total Dissolved Solids (TDS)
The most significant distinction is the level of Total Dissolved Solids (TDS), which is the concentration of inorganic salts and organic matter dissolved in water. Pure water, such as deionized or distilled, has a TDS of nearly zero. Tap water, on the other hand, can have a TDS of anywhere from 35 to 500 parts per million (ppm).
Impact on Taste and Health
The mineral content in tap water directly affects its taste. The presence of minerals like calcium and magnesium can contribute to a desirable taste, which is why pure water can often taste 'flat'. Some of these minerals are also beneficial for health, providing dietary intake of calcium and magnesium. Conversely, pure water that has had these minerals stripped away may absorb minerals from whatever it touches, including your body over time, which some health experts advise against for long-term consumption.
Common Uses
- Pure Water: Due to its lack of minerals, pure water is essential for applications where residue or mineral deposits could cause problems. This includes scientific laboratories, pharmaceutical manufacturing, automotive uses (radiators, batteries), and even professional window cleaning to avoid streaks.
- Tap Water: As a safe and affordable option, tap water is ideal for most everyday domestic purposes. This includes drinking, cooking, bathing, and cleaning where mineral content is not an issue.
Comparison Table: Pure Water vs. Tap Water
| Feature | Pure Water (e.g., Distilled, RO) | Tap Water |
|---|---|---|
| TDS Level | Close to 0 ppm | Varies, typically 35-500 ppm |
| Process | Distillation, Reverse Osmosis, Deionization | Municipal treatment, filtration, disinfection |
| Mineral Content | Very low to non-existent | Contains naturally occurring minerals and salts |
| Taste | Often described as 'flat' or tasteless | Varies by location, often influenced by minerals |
| Primary Use | Scientific labs, industrial processes, specific medical needs | Domestic drinking, cooking, bathing, general use |
| Regulation | Regulated by the FDA (for bottled) or manufacturing standards | Regulated by the EPA and local water authorities |
| Cost | More expensive to produce | Inexpensive and readily available |
Conclusion: Which is Right for You?
When deciding between pure water and tap water, the best choice depends entirely on the intended application. For most day-to-day needs, such as drinking and cooking, tap water is a safe, regulated, and cost-effective option, and it may provide essential minerals. For specific industrial or scientific purposes that require the removal of all dissolved solids, pure water is necessary. It's crucial to understand that 'pure' doesn't always mean 'better' for drinking, especially when beneficial minerals are removed during the purification process. Ultimately, while municipal tap water is a mixture of substances, it is a safe and reliable water source for the majority of the population.
The Difference Between Pure Water and Regular Tap Water
Water is a compound made up of Hydrogen and Oxygen ($H_2O$). However, the tap water delivered to our homes contains additional minerals and elements, such as calcium and magnesium, which means it is not chemically pure water. The purity of tap water can also depend on the water source and whether it is hard or soft. Pure water removes all of these extra components through intensive purification processes.
