X-rays cannot travel through water effectively due to the photoelectric effect, where low-energy soft X-rays are absorbed by water molecules, producing free electrons and holes in atomic structures. Soft X-rays, typically with energies below 1 keV, are absorbed much more strongly than hard X-rays, which have higher energies (over 50 keV) and can penetrate various materials, including water. The absorption characteristics of X-rays depend on their energy, with lower-energy X-rays being less penetrating. This interaction explains why soft X-rays are filtered out during medical imaging to minimize radiation exposure. Understanding these principles is crucial for applications in medical physics and imaging technologies.