The ES toilets look like ordinary toilets from the outside, but there are twin squatting pans inside. One of the pans is used continuously until the vault beneath it is about three-quarters full of faeces, which typically takes about six months. The user urinates into the hole in the front and throws a cup of ash or sawdust into the chamber after each defecation.

After the first pit is three-quarters full, it is filled with soil or ash and closed, while the second chamber is put into use. The faeces in the first chamber will be partially composted before it is closed and will continue to compost as the second chamber is used. The faeces will be fully composted and safe to use after about one year.