What are Total Dissolved Solids (TDS)?Updated 3 months ago

What is TDS?

Total Dissolved Solids (TDS) is a measurement of all the substances dissolved in water — expressed in parts per million (ppm) or milligrams per litre (mg/L). These dissolved solids include minerals, salts, metals, and other compounds that come from the environment, pipes, and treatment processes.

What's typically in tap water TDS?

The dissolved solids in tap water can include:

• Minerals (calcium, magnesium, sodium, potassium)
• Heavy metals (lead, copper, chromium)
• Nitrates and nitrites (from agriculture)
• Fluoride and chloramine (added during treatment)
• Pharmaceutical residues and industrial compounds

While many of these are harmless at low levels, others — like lead or nitrates — are harmful even in small amounts.

How is TDS measured?

The TDS meter included with your ZeroWater pitcher measures the electrical conductivity of the water. Dissolved ions conduct electricity; pure water does not. A reading of 000 means virtually no dissolved ions are present.

Is a higher TDS always bad?

Not necessarily. Some minerals like calcium and magnesium are beneficial to health. However, a high TDS reading may also include harmful substances — and there's no way to know which dissolved solids are present from the TDS reading alone. ZeroWater removes them all, giving you a clean baseline.

What's the TDS of tap water in Europe?

TDS levels vary significantly by location. UK tap water typically reads between 100–400 ppm. Softer water areas (Scotland, parts of Wales) may read as low as 20–50 ppm; harder water areas (south-east England) can read 300–500 ppm.