What is TDS in bottled water?

TDS (total dissolved solids) is the total amount of minerals and other substances dissolved in water, usually given in milligrams per litre (mg/L), which is the same as parts per million (ppm).

European and UK labels usually show dry residue at 180 °C instead. This is what is left after a litre of water is evaporated at 180 °C. It is close to TDS but measured differently, so we show which basis each brand uses.

How the rules use TDS

• US: to be called "mineral water", water must contain at least 250 ppm TDS and come from a protected underground source. Mineral water under 500 ppm must say "low mineral content", and over 1,500 ppm "high mineral content".^[1]
• US, other bottled water: the FDA quality limit for TDS is 500 mg/L. Mineral water is exempt, and the FDA notes this limit is about appearance and taste, not health.^[1]
• UK/EU natural mineral water labels: "very low mineral content" means a fixed residue of 50 mg/L or less, "low mineral content" 500 mg/L or less, and "rich in mineral salts" more than 1,500 mg/L.^[2]
• The US EPA's non-enforceable secondary guideline for tap water TDS is 500 mg/L, set for taste and appearance.^[5]

What TDS does and does not tell you

TDS is one number for everything dissolved. Two waters with the same TDS can have very different calcium, sodium or bicarbonate. Use the full mineral breakdown on each brand page to see what makes up the total.