The addition of particular substances, e.g. natural clay, bentonite, organic polymers, air, foam, fibres, fresh cow-dung, to drilling water increases viscosity and hence improves removal of cuttings and stabilises the borehole.
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.