Diffusion lengths have been measured in H2O as a function of boric acid concentration. From these measurements of diffusion lengths, the diffusion parameters of water were determined by an improved method of analysis. The diffusion parameters for water reported are: the microscopic absorption cross section σa = 326.9 ± 1.6mb, the diffusion coefficient = 35,850 ± 100 cm2/sec and the diffusion hardening coefficient H = 2900 ± 350 cm4/sec.