The marketing surrounding purified water has led to the rise of a specific product: water first stripped of all solids through reverse osmosis (RO) and then intentionally made alkaline. This specialized water is often promoted with claims of superior hydration and internal balancing. The central question remains whether this costly modification provides any verifiable advantage over standard drinking water for a healthy individual. Answering this requires examining the purification process, the nature of alkalinity, and the current scientific consensus regarding its effects.
What Reverse Osmosis Does to Water
Reverse Osmosis (RO) is a highly effective purification method that uses pressure to force water molecules through a semi-permeable membrane. This process separates the water from nearly all Total Dissolved Solids (TDS), including chemicals, contaminants, and heavy metals. The resulting product is water with exceptional purity, often approaching the quality of distilled water. However, the membrane removes not only pollutants but also naturally occurring minerals like calcium, magnesium, and potassium. Since these minerals stabilize the water’s pH level, their removal often results in a slightly acidic product, typically falling between pH 5 and pH 7.
Defining Alkaline Water and Its Sources
The pH scale measures the acidity or alkalinity of a liquid, ranging from 0 to 14, with 7 being neutral. Alkaline water is defined as water that has a pH level higher than neutral, generally falling between pH 8 and pH 9. Alkalinity can be achieved through two primary mechanisms. The first is naturally occurring, where water flows over mineral deposits, absorbing compounds that raise its pH. The second is through artificial treatment, which involves the deliberate introduction of alkaline compounds into purified water.
The Process of Alkalizing RO Water
Since the RO process produces de-mineralized, slightly acidic water, it must be modified to meet the criteria of alkaline water. This modification is typically done by adding a post-filtration stage called remineralization. Specialized alkaline filters or cartridges are installed as the final step in the purification system. These filters often contain crushed mineral media, such as calcite, dolomite, or a blend of calcium, magnesium, and potassium compounds. As the purified water passes over this media, it dissolves a controlled amount of minerals, raising the TDS and the pH level. The alkalinity is achieved through intentional modification, reintroducing specific minerals stripped out during the initial RO stage.
Scientific Review of Health Claims
Advocates suggest alkaline water can improve hydration, neutralize systemic acid, and aid in detoxification. However, the body is equipped with robust homeostatic mechanisms, managed by the lungs and kidneys, to keep blood pH tightly controlled within a narrow, slightly alkaline range of 7.35 to 7.45. Introducing alkaline water does not significantly alter this systemic balance, as the stomach’s highly acidic environment (pH 1.5 to 3.5) neutralizes the water’s alkalinity immediately upon ingestion. While some small studies suggest alkaline water with a pH of 8.8 may help deactivate pepsin, an enzyme implicated in acid reflux, this research is limited and requires further clinical validation. The minerals added back, such as calcium and magnesium, are beneficial, but the quantities found in alkalized water are minimal compared to intake from a balanced diet. Ultimately, current large-scale clinical evidence does not support the extraordinary health claims made for alkaline water beyond the benefits of drinking purified water.
Practical Considerations and Potential Concerns
The choice to use alkalized RO water involves practical trade-offs beyond physiological effects. Adding remineralization cartridges introduces ongoing maintenance requirements, as these filters must be replaced regularly to maintain the intended pH and mineral content. This specialized filtration contributes to a higher overall cost compared to standard RO or tap water. For most healthy consumers, alkaline water consumption is considered safe. However, water with a very high pH, sometimes exceeding 9.8, can potentially cause mineral scaling inside household appliances or plumbing over time. Individuals with pre-existing kidney conditions are sometimes advised to exercise caution, as consuming water with high mineral loads, particularly potassium, could pose a rare risk.