What Is TDS in Water? Everything You Need to Know

If you've ever looked at a bottled water label and seen “TDS” listed, you're not alone in wondering what it means — and whether it matters.

TDS, or Total Dissolved Solids, is one of the most important indicators of water quality. It measures the total concentration of dissolved substances in your water, including minerals, salts, metals, and organic matter.

Here's what you need to know.

What Does TDS Stand For?

TDS stands for Total Dissolved Solids. It refers to the combined amount of inorganic salts and organic matter dissolved in water. These include:

• Minerals like calcium, magnesium, and potassium
• Salts like sodium and chloride
• Metals like iron, zinc, and copper
• Other compounds like nitrates, sulfates, and bicarbonates

TDS is measured in milligrams per litre (mg/L) or parts per million (ppm) — these units are interchangeable.

What Is a Good TDS Level for Drinking Water?

Not all TDS is bad. In fact, some dissolved minerals are beneficial. Here's a general guide:

The World Health Organisation considers water with TDS under 300 ppm to be “excellent” and under 600 ppm to be “acceptable.”

Does Low TDS Mean Clean Water?

Not necessarily. A low TDS reading tells you the water has few dissolved solids, but it doesn't tell you what those solids are. Water with a TDS of 50 ppm could still contain trace contaminants like PFAS, microplastics, or heavy metals — these are present in such small quantities that they barely affect the TDS reading.

That's why TDS alone isn't enough to judge water quality. It's one piece of the puzzle.

Does High TDS Mean Unsafe Water?

Not always. Many natural mineral waters — like Evian (309 ppm), San Pellegrino (854 ppm), or Gerolsteiner (2,527 ppm) — have high TDS because they're rich in calcium, magnesium, and bicarbonates. These minerals are actually good for you.

The concern with high TDS is when it comes from contaminants rather than beneficial minerals — things like lead, arsenic, or industrial chemicals.

How Is TDS Measured?

TDS is typically measured using a TDS meter, which works by passing an electrical current through the water. Since dissolved solids conduct electricity, higher conductivity means higher TDS.

You can also find TDS listed on:

• Bottled water labels
• Annual water quality reports from your local supplier
• Water testing kits

TDS in Popular Bottled Water Brands

Here's how some well-known brands compare:

As you can see, there's a huge range. Purified waters like Aquafina strip almost everything out, while natural mineral waters retain their dissolved minerals.

How to Check TDS in Your Bottled Water

The easiest way to check the TDS and full mineral breakdown of any bottled water is to scan it with the Vera app. Just scan the barcode and you'll get a complete purity report — including TDS, mineral content, pH, contaminant flags, and an overall purity score.

The Bottom Line

TDS is a useful starting point for understanding your water quality, but it doesn't tell the whole story. A moderate TDS (150–300 ppm) from natural minerals is generally ideal. What matters more than the number itself is what's actually dissolved in your water — and whether it's beneficial minerals or harmful contaminants.