The statistical segment length of a large number of flexible and rigid polymers dissolved in water is calculated. For these calculations, the constant value of the Flory's parameter I broken vertical bar (I broken vertical bar = 2.6 x 10(23) cgs) along with its values obtained from an equation proposed for polymers exhibiting a significant draining effect (Colloid Polym Sci 273: 626-632, 1995) are used. Applying the first approximation for I broken vertical bar, a very low statistical segment length for the polymers dissolved in water is obtained, while in the second case the statistical segment length is almost identical with the values obtained when these polymers are dissolved in an organic solvent. Moreover, we show that there is an optional application of the modified universal calibration of the gel permeation chromatography (J Polym Sci B Polym Phys 41: 707-710, 2003), only if we use values of I broken vertical bar obtained via the second approximation for polymers presenting a significant draining effect (Colloid Polym Sci 273: 626-632, 1995).