A manhole is the top opening to a sewer system. A person can enter it to maintain the sewer. If it is not in use, it is covered with a cap to avoid injuries.
Perspectives are different frameworks from which to explore the knowledge around sustainable sanitation and water management. Perspectives are like filters: they compile and structure the information that relate to a given focus theme, region or context. This allows you to quickly navigate to the content of your particular interest while promoting the holistic understanding of sustainable sanitation and water management.