Tds Calculator

µS/cm
Measured by EC meter. Water at 25°C.
Typical: 0.55–0.70 for drinking water; 0.64 is most common.
Chemistry

Calculate Total Dissolved Solids (TDS) from conductivity measurement or estimate water quality category.

Formula

TDS (mg/L) = Conductivity (µS/cm) × conversion factor k
  • k ranges from 0.55 to 0.90 depending on ion composition. 0.64 is standard for most water.
  • WHO guideline: TDS < 600 mg/L acceptable for drinking; < 300 preferred.
  • TDS of 0–50 mg/L: de-ionized water; 50–150: good quality; >1000: brackish.

EC = 500 µS/cm, k = 0.64

Inputs
  • Electrical Conductivity (EC): 500 µS/cm
  • Conversion Factor (k): 0.64

TDS = 500 × 0.64 = 320 mg/L — Fair water quality.

Frequently asked questions

Is low TDS water safe to drink?
Very low TDS (< 10 mg/L) water, such as RO/distilled, may lack minerals. Some studies suggest moderate TDS is beneficial.
What raises TDS in water?
Dissolved minerals (calcium, magnesium, sodium), agricultural runoff, industrial discharge, and water treatment chemicals.