The four types of sanitation are water sanitation, solid waste management, wastewater management, and hygiene promotion. Water sanitation involves providing safe drinking water and proper sanitation facilities. Solid waste management involves collecting, transporting, and disposing of solid waste in a safe and efficient manner. Wastewater management involves treating wastewater to reduce pollutants and prevent contamination of water sources. Hygiene promotion involves educating people on proper hygiene practices to reduce the spread of disease.