Context
Millions of people around the world drink mineral water every day because their tap water is unsafe or because they prefer the taste. It’s packed with naturally occurring minerals that support bone and muscle health and governments and health organisations promote it as a clean, reliable source of hydration.
1. Definition and Origin of Mineral Water
- Source: Mineral water originates from protected underground reservoirs, such as springs or aquifers, rather than surface sources like rivers.
- Natural Acquisition: It acquires minerals and trace elements through geological processes as rainwater and snowmelt percolate through rock layers like limestone, granite, or sandstone.
- Consistency: Unlike tap water, mineral water must have a specific and stable composition of minerals that remains consistent over time.
2. Mineral Composition and Effects
- Common Minerals: Includes calcium, magnesium, sodium, potassium, bicarbonates, sulphates, chlorides, and silica.
- Hardness: High levels of calcium and magnesium make water “hard” and contribute to its distinct mouthfeel.
- Flavor Profiles:
- Bicarbonates: Neutralize acidity and can give water a slightly sweet finish.
- Sulphates: Associated with magnesium-rich springs, adding a faint bitter or saline note.
- Total Dissolved Solids (TDS): Dissolved minerals determine the water’s TDS level, which affects how it interacts with food and the human body.
- Quick Facts on Water Minerals
| Mineral | Contribution to Water | Effect/Observation |
| Calcium | Hardness | Contributes to bone and muscle health; creates a “chalky” sensation. |
| Magnesium | Hardness | Essential for muscle function; can add a slightly bitter note at high levels. |
| Bicarbonates | Alkalinity | Helps neutralize acidity and can provide a slightly sweet finish. |
| Sulphates | Salinity | Often found in magnesium-rich springs; adds a faint bitter or salty taste. |
3. Regulatory Framework in India
- Governing Bodies: Regulated by the Food Safety and Standards Authority of India (FSSAI) and the Bureau of Indian Standards (BIS).
- Mandatory Standards:
- Source Protection: Must come from protected underground sources like natural springs or borewells.
- Chemical Treatment: Producers are prohibited from chemically treating the water to alter its mineral composition.
- Permitted Processing: Only physical processes like filtration, decanting, aeration, or sterilization are allowed.
- Certification: Sellers must have an FSSAI license and a BIS certificate (IS 13428).
- Labeling: Labels must state the location and name of the source and the levels of various minerals.
4. Tap Water vs. Mineral Water in India
- Source of Tap Water: Primarily drawn from rivers and borewells.
- Treatment: Municipalities use chlorine and alum to disinfect and remove pathogens, a process not required for mineral water if the source is bacteriologically pure.
- Regional Variation:
- High Mineral Areas: Rajasthan, Gujarat, and parts of Delhi-NCR have very high mineral content in groundwater.
- Low Mineral Areas: Mumbai and parts of Kerala have much softer water with lower mineral levels.
- Governance: Tap water is a State responsibility, while the Union government sets the standards.
5. Distilled Water and Industrial Use
- Distillation Process: Water is boiled into steam and condensed back to liquid, leaving all minerals and contaminants behind.
- Human Consumption: Distilled water is not advised for regular consumption because it lacks essential minerals and can draw minerals out of the body.
- Industrial Use: Industries often demineralize water to prevent scaling in boilers or cooling systems.
6. Osmosis vs Reverse Osmosis
| Feature | Osmosis | Reverse Osmosis (RO) |
| Nature of Process | A natural and spontaneous biological/physical process. | An artificial or mechanical process. |
| Direction of Flow | Solvent (water) moves from lower solute concentration to higher concentration. | Water is forced from higher solute concentration (contaminated) to lower concentration (pure). |
| External Pressure | Does not require any external energy or manual pressure. | Requires high mechanical pressure to overcome natural osmotic pressure. |
| Role of Membrane | The semi-permeable membrane allows water through but blocks large molecules. | The membrane acts as a ultra-fine filter to remove dissolved salts, minerals, and pathogens. |
| Primary Goal | To achieve equilibrium (balance) in concentration on both sides. | To purify water by removing contaminants and dissolved solids. |
| Common Example | Plants absorbing water from the soil through their roots. | Household water purifiers or large-scale desalination of seawater. |
7. Common Water-Borne Diseases
- Bacteria: Cholera, Typhoid, Dysentery, Shigellosis, E. coli.
- Viruses: Hepatitis A, Hepatitis E, Polio, Rotavirus, Norovirus.
- Protozoa/Worms: Giardiasis, Cryptosporidiosis, Ascariasis.
- Chemical/Others: Arsenicosis, fluorosis, and various infections from harmful algal blooms.
Q. Which of the following minerals contribute to water hardness?
1. Calcium
2. Magnesium
3. Sodium
Select the correct answer:
A. 1 and 2 only
B. 2 and 3 only
C. 1 only
D. 1, 2 and 3
Answer: a
Explanation:
Based on the scientific principles of water chemistry outlined in the provided article:
Calcium (1) and Magnesium (2): These are the primary minerals responsible for water hardness. When water contains high levels of these two minerals, it is classified as "hard" water. These minerals contribute to the "mouthfeel" of the water and are known to form "scales" or mineral deposits in kettles, pipes, and appliances.
Sodium (3): While sodium is a common mineral found in water, it does not contribute to hardness. In fact, water softening processes often work by replacing calcium and magnesium ions with sodium ions to "soften" the water.
