Traditionally, toilets use three to five gallons per flush. If an eighteen-liter per flush toilet is removed and a six-liter per flush toilet is put in its place, 70% of the water flushed will be saved while the overall indoor water use by will be reduced by 30%.[67] It is possible to have a toilet that uses no water. A composting toilet treats human waste through composting and dehydration, producing a valuable soil additive.[68] These toilets feature a two-compartment bowl to separate urine from feces.