Backwater valve

Plumbing · Floor Drains · printed page 291 (PDF page 292)

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Book index entries

Backwater Valve Drains – Plumbing – Backwater Valve Plumbing

Text in the illustration

normal operation
drain backup
foundation wall
waste stack
clean-out
basement
floor drain
cross section
drain pipe

Generated explanation

The illustration shows a basement plumbing cross section with a trapped floor drain connected to a waste stack and drain pipe beneath the slab. A backwater valve is installed in the horizontal floor-drain branch between the trap and waste stack. An enlarged view of normal operation shows the valve flap open, allowing drainage toward the stack. A second enlarged view shows reverse flow closing the flap during a drain backup, preventing backed-up wastewater from reaching the floor drain. The foundation wall, basement slab, surrounding soil, and a clean-out on the waste stack provide installation context.