The Fernco Non-Return Valve for DN100 Pipes is a specialised drainage component designed to prevent backflow and intrusion in sewage systems. This valve acts as a protective barrier, allowing waste to flow freely towards the mains while blocking the reverse passage of sewage and pests such as rodents into residential or commercial properties. It serves as an effective flood prevention measure, protecting toilets, waste pipes, and plug holes from damage caused by backflow in blocked sewerage networks. Engineered for ease of use, the unit features a retrofit design that enables direct push-fit installation into existing manhole pipe inlets. It is a maintenance-free system that provides continuous, passive protection for infrastructure, roads, and buildings without the need for ongoing servicing or manual inspection. The design ensures that drainage operations continue smoothly while maintaining essential safety standards against flooding and pests.