Understanding pH and Alkalinity
Before exploring how magnesium affects water, it is important to distinguish between pH and alkalinity. A substance's pH measures its acidity or alkalinity on a scale of 0 to 14, with 7 being neutral. However, alkalinity is the water's ability to neutralize acid, which depends on its mineral content and is referred to as its buffering capacity. While a higher pH is characteristic of alkaline water, the total alkalinity from dissolved minerals like calcium, magnesium, and bicarbonates determines its buffering strength.
How Different Magnesium Compounds Affect Water pH
Not all magnesium compounds are created equal when it comes to influencing water's pH. The result depends heavily on the compound's chemical properties and its reaction with water.
Magnesium Hydroxide ($Mg(OH)_2$)
Magnesium hydroxide, commonly known as Milk of Magnesia, is a powerful alkalizing agent. In a saturated solution, it can raise the pH to around 10. Its limited solubility in water is a key feature; as the water becomes more acidic, more $Mg(OH)_2$ dissolves, neutralizing the acid and releasing hydroxide ions to increase the pH. This compound is used in wastewater treatment to neutralize acidity. When combined with carbonated water, it reacts to form magnesium bicarbonate.
Magnesium Bicarbonate ($Mg(HCO_3)_2$)
This is a highly bioavailable form of magnesium and a true alkaline mineral salt. Magnesium bicarbonate is only stable when dissolved in water, not in solid form. An aqueous solution typically has a pH of around 8.3 and contains bicarbonate ions that act as a buffer. It is the form found in high-quality mineral-rich alkaline waters. A DIY method involves adding magnesium hydroxide to carbonated water to produce it.
Magnesium Citrate
Magnesium citrate is a widely used supplement, known primarily for its laxative effects. It is formed from magnesium and citric acid. While studies show it can increase urinary pH, it is not an effective way to produce alkaline drinking water for general consumption, nor is it primarily intended for that purpose. It does not significantly alter the pH of the water it is dissolved in for drinking.
Magnesium Chloride ($MgCl_2$)
Magnesium chloride is the salt of a strong acid (hydrochloric acid, HCl) and a weak base (magnesium hydroxide). As a result, when dissolved in water, it forms a solution that is close to neutral or very slightly acidic due to minor hydrolysis. It does not increase the water's pH and, therefore, does not make it alkaline in the way that magnesium hydroxide or bicarbonate does.
Comparison of Magnesium Compounds for Water Alkalinity
| Feature | Magnesium Hydroxide ($Mg(OH)_2$) | Magnesium Bicarbonate ($Mg(HCO_3)_2$) | Magnesium Chloride ($MgCl_2$) |
|---|---|---|---|
| Effect on pH | Significantly increases pH (up to ~10) | Increases pH (to ~8.3), acts as a buffer | Neutral or slightly acidic (~7) |
| Common Use | Antacid, laxative, wastewater treatment | Mineral supplement in water | Supplement, food additive, electrolyte |
| Source | Produced industrially or from sea salt | Forms in water when CO2 reacts with Mg | Mined from salt deposits or brine |
| Alkalizing Strength | Strongest | Moderate | None |
| Bioavailability | Limited; converts to bicarbonate with CO2 | High | High |
A Simple DIY Alkaline Water Recipe (using Magnesium Hydroxide)
If you want to create your own magnesium-rich alkaline water, the magnesium hydroxide and carbonated water method is effective.
- Prepare the ingredients: You will need pure magnesium hydroxide powder or Milk of Magnesia and 1 liter of plain, unsweetened carbonated water.
- Add the magnesium: Pour about 1/4 teaspoon of magnesium hydroxide powder into the carbonated water.
- Seal and shake: Quickly reseal the bottle to prevent the escape of fizz, as the mixture will bubble. Shake vigorously for a minute or two.
- Wait for clarity: The solution will appear cloudy at first. Let it stand for several hours until it becomes completely clear, which indicates the conversion to magnesium bicarbonate.
- Store and use: Store the finished solution in the refrigerator. Consume small amounts daily (e.g., 30-50 mL diluted in regular water).
Health Claims and Considerations for Alkaline Water
While marketing for alkaline water often makes broad health claims, it is important to be aware of the scientific consensus. The human body has sophisticated mechanisms, primarily through the kidneys and lungs, to maintain a very tight blood pH balance.
- Benefits: Some preliminary research suggests alkaline water may help with acid reflux and potentially slow bone loss, though more studies are needed for conclusive evidence. Proper hydration with any water is essential for bodily functions.
- Risks: Excessive consumption of highly alkaline water (pH > 9.5) can pose risks, especially for individuals with kidney disease, potentially leading to a mineral imbalance. Disruption of the stomach's natural acidity, necessary for digestion and killing bacteria, is another concern.
Conclusion
Adding certain forms of magnesium, particularly magnesium hydroxide and magnesium bicarbonate, can effectively make water more alkaline. However, the impact depends on the specific compound, with magnesium hydroxide being a strong alkalizing agent and magnesium chloride having no significant effect. Creating magnesium-rich alkaline water at home is a simple process involving magnesium hydroxide and carbonated water. While some health benefits are anecdotally reported, scientific evidence is limited, and excessive consumption can carry risks. For most people, the body's own regulatory systems maintain pH balance regardless of the water they drink. It's best to approach alkaline water with a balanced perspective and consult a healthcare professional, especially if you have existing health conditions like kidney disease.
Outbound Link
For more information on the potential risks and benefits of alkaline water, consult reputable health sources like the Mayo Clinic: Alkaline water: Better than plain water?.
