Putting the case for vacuum drainage

The standard for delivery of traditional gravity drainage systems reflects its rich history. Conventional gravity drainage systems rely on vertically aligned soil and waste stacks, with the location of sanitary appliances largely dictated by the position of these stacks. The maximum horizontal distance between appliances and the vertical stack is limited by drainage gradients and hydraulic performance requirements, reducing flexibility in building layouts. Each vertical stack requires multiple penetrations through intermediate floor slabs and the roof, which increases coordination requirements and introduces additional fire-stopping and waterproofing considerations. At ground level, the stacks typically discharge into below-ground drainage networks via inspection chambers or manholes, creating a system of interconnected underground pipework that requires sufficient falls and regular access for maintenance.

Rather than repeating the mechanics and standard for the design of traditional underground drainage, let us move to the heart of the matter: why, in the 21st century, are healthcare buildings still designed and constructed with internal manholes within the building envelope?

The New Hospital Programme (NHP) provides the ideal opportunity and vehicle for a complete design reset in every aspect to rethink and imagine a building where each element and design choice provides a best-in-class solution to prevent and mitigate infection spread, by starting to empower the 'thought process' before pipes are cast in concrete for the next 100 years.