Water uptake by roots is a key adaptation of plants to aerial life. Water uptake depends on root system architecture and tissue hydraulic properties, which shape the root hydraulic architecture. At the root scale the water transport has two components: the axial flow into the xylem vessels, characterized by an axial conductance; and the radial flow, related to the water flow through the peripheral cell layers, characterized by a radial conductivity. At the cellular scale, the radial water transport involves complex pathways across root tissues commonly referred as apoplastic and ‘cell-to-cell’ pathways. In our lab, we have been developing experimental and modeling approaches at different scales, in order to better understand how the components involved in water transport integrate into a full hydraulic architecture. At each level, our results show an interplay between those components and, therefore, none of them can be neglected. For example, based on a new model-assisted “cut-and-flow” method, we have shown that axial and radial conductivities are co-limiting parameters in highly-branched root systems. Other results demonstrated that, under water stress condition, the osmotic component of water transport cannot be neglected. At the cellular scale, while the two radial pathways are often considered as separate in textbooks, they are highly connected and nothing prevents water from changing route between tissues. Indeed, our current modeling and experimental work on root cross-section shows that purely apoplastic pathways are very unlikely. Water molecules rather follow a ‘cell-to-cell’ pathway, whose length depends on the permeability of the plasma membrane.