Soil properties, under the major influence of agricultural practices in cultivated fields, influence the distribution and quality of water and vary greatly in space and time. In conservation agriculture (CA), the combination of practices implemented can modify water retention and circulation. In this study, fields managed under CA and adjacent fields with regular ploughing (CONV) were used to characterize the water functioning of soils in the Adour-Garonne basin in south-western France. Hydraulic conductivity (KS), bulk density and available water capacity (AWC) of the soils were measured to a depth of 50 cm on multiple dates to assess their temporal dynamics. Mean KS was 1.5–3.0 times as high under CA (100–160 mm h−1) as under CONV (50–70 mm h−1), depending on the soil. CA had less temporal variability in infiltration capacity than CONV. Under CONV, infiltration was generally high after ploughing but decreased rapidly (by a factor of 2–20) depending on the soil and depth studied. AWC was significantly higher in the surface horizon (0–5 cm) under CA than under CONV, but the difference remained small (≤10 %) at the scale of the soil profile. In contrast, rooting depth, and thus the ability to use this AWC, was higher under CA. Thus, the changes in soil water functioning under CA seem to be related more to improved functioning of the AWC (through greater and more stable infiltration over time) and use by crops (through increased root exploration) than to an increase in the AWC itself. These elements make it possible to better evaluate effects of CA implementation on crop water supply and quantitative water management under CA.