It was previously found that the electric charge of water determines its ability to interact with other substances, including biologically significant ones. It is shown here that the electric charge of water can also determine its ability to penetrate and accumulate in living cells. In particular, it has been shown that the high penetrating ability of positively charged water determines both its active penetration into cells and accumulation in them, which creates favourable conditions for cell proliferation. At the same time, it has been shown that the low penetrating ability of negatively charged water determines its ability to slow down cell proliferation. It also discusses how medics can obtain and use water at different charges.