The root hairs are where most water absorption happens. They are long and thin so they can penetrate between soil particles and they have a large surface area for absorption of water.
|Solution||Water concentration||Concentration of dissolved solutes|
|Root hair cell cytoplasm||Low||High|
To maintain the concentration gradient and so the constant movement of water into the root hair cell by osmosis, the root hair cell actively transports mineral salts into the cell.
This means it uses energy - these cells are actively respiring in order to move mineral salts from low concentration outside of the cell to the high concentration in the cell. Thus ensuring osmosis and the transpiration stream continues.