The "b" value for water in the context of damped oscillations refers to the damping constant, which indicates how a substance reduces vibrations when attached to a spring system. The damping constant varies with temperature and cannot be defined as a single value, as it depends on the specific dynamics of the system being studied. To determine the b value for water, one must consider factors such as the mass of the object, the spring constant, and the angular velocity. Additionally, the viscosity of water plays a role in calculating the damping constant. Overall, extracting the damping coefficient from experimental data is often necessary for accurate results.