Soil laboratory columns are used to test the sealing efficiency of organic liners made of various combinations of straw and either beeflot manure or broiler litter In tests conducted in triplicate each liner was placed at the centre of a 0.6 m core of loam and submerged for 83 days under 3.25 m of low total solids (TS) wastewater The liquid and contaminant seepage-rate for each liner was monitored throughout the experiment The liner made of 85% beeflot manure and 15% straw on a dry matter basis, gave the lowest seepage rate of 19 x 10(-9) m s(-1). This same liner limited nitrogen seepage rates well below 0.6 g m(-2) d(-1), which is the limit required by most North American Environmental Authorities. Extrapolation of the seepage rates, which still decreased after 83 days, indicated that the best liner could reach sealing levels of 1 x 10(-9) m s(-1) after 128 days.