Lack of experimental data for nuclear criticality control over operations with plutonium necessitates the use of computed critical parameters for guidance. To provide guidelines for criticality safety use, survey calculations for unreflected and water-reflected spheres, semi-infinite cylinders, and semi-infinite slabs have been made, using calculational techniques confirmed by available experimental data. The Pu(metal)-water mixtures examined cover the entire range of possible moderation ratios and have isotopic 240Pu contents of 20%. Critical experiment data for water-reflected spherical systems containing Pu(NO3)4 solutions with 435g Pu/liter at 4.6 wt% 240Pu were extrapolated by means of calculations to 239Pu(metal)-water mixtures for a direct comparison between calculations and experimentally derived critical parameters. The effect of 240Pu on criticality was examined as a function of both concentration and geometry. The manner in which 240Pu affected the minimum critical mass of Pu(metal)-water systems was also determined.