EC or Electrical Conductivity of water is its ability to conduct an electric current. Salts or other chemicals that dissolve in water can break down into positively and negatively charged ions, these free ions in the water conduct electricity, so the water electrical conductivity depends on the concentration of ions.
Salinity and total dissolved solids (TDS) are used to calculate the EC of water, which helps to indicate the water’s purity. The purer water the lower conductivity or TDS. Distilled water is almost an insulator (TDS: few ppm), but saltwater is a very efficient electrical conductor (Seawater TDS around 35,000 ppm).