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TDS from Conductivity

Estimate Total Dissolved Solids (mg/L or ppm) from electrical conductivity (EC).

Typical range 0.55–0.75. For natural waters, often 0.64.
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mg/L (ppm)

Formula

TDS (mg/L) = Conductivity (µS/cm) × kₑ

kₑ is an empirical factor depending on ionic composition.

Notes

  • Conductivity measures the water's ability to carry an electrical current.
  • The factor 0.64 is a common approximation for many freshwater samples.
  • For precise work, determine kₑ experimentally for your water type.