A batch composting toilet system utilizes two or more interchangeable or movable bins. One is filled at a time and then turned aside allowed to cure while another bin fills — just as with twin-bin and triple-bin yard composters. By not continually adding fresh excrement and urine to older, more advanced material, the material decomposes more thoroughly, uninterrupted by the added nutrients, pathogens, salts, and ammonia in fresh excrement. Also by dividing the material, it can have more surface area, and thus better aeration. Batch systems require monitoring the level of the bins to determine when a bin has filled and a new one must be moved into place. However, because there is more surface area and the material is divided, there is often less or no mixing and raking of the material.