Understanding Total Dissolved Solids (TDS)
Total Dissolved Solids (TDS) is a measure of all the inorganic and organic substances dissolved in a volume of water. These substances can include minerals like calcium, magnesium, and potassium, as well as salts, and in some cases, contaminants like heavy metals or nitrates. TDS is typically measured in parts per million (ppm) or milligrams per liter (mg/L). A TDS meter measures the electrical conductivity of the water to provide a reading, as dissolved ions conduct electricity. While a TDS reading indicates the overall concentration of dissolved substances, it does not identify which specific substances are present.
How TDS Relates to Bottled Water
Bottled water brands can have vastly different TDS levels depending on their source and purification process. This is often the primary reason for the variation in taste between different brands. For instance, purified water, which often goes through processes like reverse osmosis or distillation, will have a very low TDS level, sometimes near zero, as these methods are designed to remove nearly everything from the water. Conversely, natural spring water or mineral water will have a higher TDS level because it contains minerals from its source. Regulatory bodies like the EPA set a guideline for TDS in tap water, but for bottled water, it primarily affects taste and is not always an indicator of safety.
Popular Bottled Water Brands and Their TDS Levels
Here is a look at the approximate TDS levels for some common bottled water brands. It's important to note that these values can vary slightly by batch and source.
| Brand | Water Type | Approximate TDS Level (ppm) | Key Characteristics |
|---|---|---|---|
| Aquafina | Purified | ~2-30 | Very low TDS; often described as 'flat' tasting. |
| Dasani | Purified | ~28 | Low TDS with minerals added back for taste. |
| SmartWater | Purified (Vapor Distilled) | ~20 | Low TDS from distillation, with electrolytes added. |
| Evian | Natural Mineral | ~247-300 | High, naturally-occurring mineral content from alpine source. |
| Fiji | Artesian | ~132 | Moderate, natural mineral content from volcanic rock filtration. |
| Voss | Artesian | ~23-40 | Historically low for an artesian water, but varies. |
| Nestle Pure Life | Spring/Purified | ~53-516 | Varies greatly based on source, can be high. |
| Icelandic Glacial | Natural Spring | ~52 | Moderate, naturally occurring minerals. |
| Perrier | Sparkling Mineral | ~400+ | High TDS due to natural minerals and carbonation. |
| Liquid Death | Spring Water (Canned) | ~212 | Moderate mineral content from mountain source. |
How to Choose Your Ideal Bottled Water
Choosing the 'best' bottled water is subjective and depends on your personal preferences and intended use. Here are some factors to consider:
- Taste Preference: Do you prefer the crisp, neutral taste of low-TDS purified water, or the more distinct, mineral-rich flavor of natural spring water? Low TDS water is often described as 'flat' or 'insipid,' while higher TDS can taste metallic or salty.
- Health Considerations: While the trace minerals in higher TDS waters can be beneficial, your primary source of minerals should be your diet, not water. For those with specific health conditions, such as kidney issues, a very low TDS may be preferable, but for most people, a balanced mineral content is ideal. The key is to ensure any higher TDS water is from a clean, regulated source and free of harmful contaminants.
- Use Case: For specific applications like mixing baby formula or for medical equipment, a very low TDS water like distilled or purified water is often recommended. For everyday hydration, a moderate TDS range of 50-300 ppm is often preferred for taste and mineral balance.
- Measuring Your Own Water: If you are unsure about the TDS of your water, you can purchase a small, handheld TDS meter to test it yourself. This is useful for both bottled water and tap water, especially if you use a filtration system and want to ensure it is working correctly.
Conclusion
What TDS is in bottled water varies widely, reflecting its source and purification method. Whether you choose a low-TDS purified water or a mineral-rich spring water, understanding the TDS level empowers you to make a more informed choice based on taste, health goals, and overall quality. While a higher TDS level is not inherently unsafe, investigating the mineral source is recommended. For ultimate peace of mind, pair a TDS test with more comprehensive water quality testing. The right water for you is a personal choice, balancing taste preferences with desired mineral content.
What are TDS guidelines?
- The WHO suggests less than 600 mg/L (ppm) for palatability, with 50-150 ppm considered ideal for taste and mineral balance.
- The EPA secondary drinking water regulation sets a recommended maximum of 500 mg/L, but this is a guideline, not an enforceable standard.
- Different countries and regions have their own specific guidelines for both tap and bottled water, which can vary.
