The urine can also be sent to a shallow cavity to reintegrate the nutrients into the soil, thus fertilizing nearby vegetation. The excrement, which falls into the chamber, must be covered with lime or ash and soil after each use. When the vault in use is almost full, the other is emptied, and ready for subsequent use. Ecological dry toilets do not contaminate water. Dry toilets produce about 500 liters of dry fertilizer and 5000 liters of liquid fertilizer as they transform the excrement and urine of a family in one year.
Water toilets destroy aquatic life and contribute to the general scarcity of potable water.
A dry toilet can adapt to the possibilities and tastes of each family. They can be installed inside or outside the house, and on second or higher stories of buildings. They can be built even where municipal water and sewage services are available. The dry toilet is not only an alternative in rural areas.