Why does water travel from low to high concentrations in cells?

Yes, things do travel from high concentration to low concentration, but a living cell has its membrane, which does not permit "things" to p through easily. Only water, salts, and proteins that are extremely small can diffuse through the lipid bilayer without exhausting energy. Thus, water flows from a higher concentration of water (thus higher water potential) to a lower concentration of water (lower/more negative water potential in surrounding).