TDS-Conductivity Relationship

Definition

The field rule of thumb estimating Total Dissolved Solids from conductivity as TDS (mg/L) is approximately 0.7 times conductivity in microS/cm.

The 0.7 factor lets operators infer dissolved solids from a fast conductivity reading instead of a slow evaporation test. It is only an approximation that varies with ion type, concentration, and temperature, but it is accurate enough for real-time operational control in most freshwater systems. It connects the continuous conductivity proxy back to the classical mass-based TDS measurement.

Related concepts

Conductivity · Total Dissolved Solids Measurement · Dissolved Solids

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Part of The Blueprint of Water · 📏 measurement