Method and apparatus for effecting the natural simultaneous biochemical decomposition of feces and urine involving the decomposition of the feces and the urine independently of each other and at different temperature but within a single apparatus. The urine is directed alone to an absorbent mineral pad and permitted to decompose as it passes slowly therethrough. The feces are mixed with a vegetable material and introduced into a separate decomposition area to a first stage where the temperature is maintained at 30*c, thereafter to a second stage where the temperature is maintained at 50* to 70*c. and thereafter to a third or final maturing stage where decomposition is completed. Excess air is introduced to the feces decomposition area during the decomposition and the feces mixture is maintained at a moisture level of 60% to 70% throughout the process, the decomposed urine being utilized to maintain the moisture level. The apparatus includes the principal chamber having at least a pair of canted planar members arranged in different planes but in a sequence, mineral wool members being carried by each of said members, said members being positioned to receive the urine and permit same to flow slowly, sequentially therethrough. The mats may be impregnated with nitrogen bacteria to aid decomposition. The feces are mixed with vegetable matter and introduced into the principal chamber, the floor of which being sloped in stages, the greater slope being at the first stage for initially receiving the mixture, the next stage being of lesser slope and the last stage being sloped in an opposite direction whereby totally defining a bowl-like configuration. The temperature within and the flow of air through the chamber is controlled.