An apparatus for bio-composting domestic waste from residential dwellings, comprised of a tank, a multi-chambered liner and a separator. Domestic waste influent enters one end of a sluice, which has ribs on its surface directing the influent onto the upper section of an inclined sieve. The inclined sieve is angled downward and is permeable. The influent waste flows down the inclined sieve, and free water drops downward through the sieve while separated waste solids slide off the lower edge of the inclined sieve. The multi-chambered liner is set inside the tank under its lid. The multi-chambered liner is partitioned into a first chamber running the length of the liner on one half its wide, which the other half its width is subdivided into a series of smaller sub-chambers running the length of the liner. The chambers are separated by permeable partitions. The walls of the liner are permeable, as well. Water separated from the influent through the sieve falls into the first several of the smaller sub-chambers, while the dewatered solids discharge off the bottom edge of the inclined sieve into the first chamber. The separated waste solids are bio-composed in the first chamber, preferably by the larvae of fungus gnats, while the separated free water passes through the partitions between the series of smaller sub-chambers, removing any remaining entrained solid matter. The free water passes through the permeable walls of the multi-chambered liner and out an outlet port in the tank wall.