The Role of Sodium in Your Body
Sodium, often consumed in the form of sodium chloride (table salt), is an essential electrolyte that plays a critical role in several bodily functions. The human body requires sodium to maintain a healthy fluid balance, control blood pressure, and ensure proper nerve and muscle function. The kidneys regulate sodium levels in the body, flushing out excess amounts through urine to prevent them from building up. However, when sodium intake consistently exceeds what the body can efficiently process, it can lead to various health problems.
How Sodium Gets into Your Water
Sodium chloride finds its way into bottled water in a few different ways:
- Naturally: As water flows through underground rock and soil, it can naturally dissolve and pick up minerals, including sodium. The level depends on the geographical source of the water. Natural spring waters or mineral waters, for instance, can have varying, but often low, concentrations of sodium.
- During Processing: Some bottled water companies add electrolytes, which can include sodium, back into their purified or distilled water to improve the taste. This is common for brands that use reverse osmosis to purify water, which initially removes most minerals.
- Water Softeners: For those with private wells, a water softener system can significantly increase the sodium content in drinking water. These systems use an ion exchange process, replacing calcium and magnesium with sodium ions.
When is Bottled Water's Sodium Content a Concern?
For the majority of the population, the sodium levels in bottled water are too low to cause any concern. A large portion of daily sodium intake comes from processed foods, not drinking water. However, there are specific groups of people who should pay attention to the sodium content of their bottled water:
- Individuals on Sodium-Restricted Diets: People with medical conditions like hypertension (high blood pressure), congestive heart failure, or kidney disease are often placed on a low-sodium diet by their healthcare provider. The EPA recommends that people on very low-sodium diets consume no more than 20 mg/L of sodium from drinking water.
- People with High Blood Pressure: Chronic high intake of sodium is a major risk factor for developing hypertension. While sodium from water is typically a minor contributor, it can add up, especially if dietary intake is already high. A study in coastal Bangladesh found that high-sodium drinking water was directly linked to raised blood pressure in the population.
- Infants: For infants whose formula is prepared with tap water, a water softener could elevate sodium levels. While it's generally not harmful, consulting with a pediatrician is recommended for those using water from a well or softened source.
Comparison of Bottled and Tap Water Sodium
It is difficult to generalize about the sodium content of all tap water, as it varies widely based on geographic location and whether it is treated with a water softener. However, below is a general comparison of sodium levels based on different water types, including examples found in research.
| Water Type | Typical Sodium Level Range | Key Considerations |
|---|---|---|
| Purified Bottled Water | ~0-10 mg/L | Undergoes filtration (like reverse osmosis) to remove minerals. Some brands may add electrolytes for taste. |
| Spring Bottled Water | ~5-20 mg/L | Naturally sourced, with mineral content dependent on the geological source. Levels tend to be consistently low. |
| Mineral Bottled Water | Highly variable, often 10+ mg/L | Sourced from mineral springs, with a higher, but variable, mineral content. High levels can produce a salty taste. |
| Tap Water (Unsoftened) | Variable (typically <20 mg/L) | Levels depend on the source (groundwater vs. surface water) and natural mineral content. |
| Tap Water (Softened) | Variable (can exceed 100 mg/L) | A significant source of sodium for households with a water softener system. |
How to Make an Informed Choice
To determine if your bottled water is contributing significantly to your daily sodium intake, follow these steps:
- Check the label: Always read the nutritional information on the bottled water label. The sodium content is listed in milligrams (mg). Low-sodium water is often labeled as such.
- Choose wisely: If you are on a sodium-restricted diet, opt for brands with lower sodium concentrations. Purified, distilled, or demineralized options often have the lowest sodium content.
- Consider your tap water: If you drink tap water, especially from a private well with a softener, consider getting it tested for sodium levels. Your local health department can help with this.
- Prioritize food sources: Remember that your diet is the main source of sodium. Focus on reducing processed and restaurant foods to make the biggest impact on your overall intake.
Conclusion
In summary, the trace amounts of sodium chloride found in most bottled water are not harmful to the average healthy person. The human body requires sodium for normal function, and water is a minimal source compared to food. However, for individuals managing conditions like hypertension or kidney disease, or those on medically supervised low-sodium diets, it is important to be mindful of all sources of sodium, including drinking water. Checking bottled water labels and being aware of tap water sources can ensure you stay hydrated without compromising your health goals. Focusing on dietary changes remains the most effective strategy for managing overall sodium intake and preventing related health issues.
For more information on sodium intake and your health, the American Heart Association offers extensive resources on its website: Heart.org/sodium.
