Interface water cluster anions (H2O)(n)(-) (n less than or equal to 12) composed of two to four fragments are simulated in the unrestricted Hartree-Fock approximation with the second order Moeller-Plesset perturbation theory corrections taken into account with the 6-31++G(**) basis set either augmented or not with the floating center of eight s functions. A linear dependence of the circumsphere radius involving central molecules of the anions on 1/n provides an estimate of the excess electron radius in condensed water (about 2.5 Angstrom). Vertical detachment energies, approximated with linear dependences on n(-1/3) are extrapolated to the values around 3.4 eV for bulk water.