Root hairs are small hair-like extensions of the outer layer of root CELLS. Roots can have an amazingly large number of root hairs. Root hairs increase the surface area of the roots, increasing the capacity to absorb nutrients and water. Root hairs greatly increase the surface area of roots. Root hairs absorb nutrients and water. Root hairs are often destroyed when a plant is dug from the soil. New root hairs will quickly form as long as the roots themselves are undamaged.