Tensiometers were installed to study seepage from an excavated earth tank used for farm water supplies near Badgingarra, W.A. Seepage was limited by a layer of soil about 0.2 m thick with hydraulic conductivity about one-tenth of that of soil deeper in the profile. The seepage limiting layer bounds the excavated tank. Water balances of several earth tanks were used to estimate hydraulic conductivities of soils in situ. Most of the variation of hydraulic conductivity could be accounted for by sand content, exchangeable magnesium percentage, exchangeable sodium percentage, and dithionite extractable iron in the soils. Laboratory measurements of the hydraulic conductivities of disturbed samples had no relevance to the field situation.