The method of the determination of radium isotopes ²²⁶Ra and ²²⁸Ra in the saline and mineral waters based on the LSC with the separation of a and b rays is presented. Concentrations of radium isotopes were calculated using Bateman equations for a and b components of ²²⁶Ra, ²²⁸Ra, without waiting for the radioactive equilibrium. The concentrations of these isotopes are very low in most mineral waters found in the market with the exception of two waters where the concentration of long life isotope ²²⁶Ra is high. Therefore, it is necessary to investigate the radium isotopes concentration in drinking mineral waters.