Flexible Adaptor Coupling 4″ Cast Iron to 4″ Plastic

The Kalsi Group Flexible Adaptor Coupling 4″ Cast Iron to 4″ Plastic is a purpose-engineered rubber drainage coupling that creates a secure, watertight transition between existing 4-inch cast iron soil or drain pipe and modern 4-inch uPVC or PVC-U plastic pipe. Manufactured in Birmingham as part of the Kalsi Aquaflow underground drainage system, it is the go-to solution for UK tradespeople and DIY renovators tackling drain repairs, house extensions, and replumbing projects where old and new pipework must be joined reliably.

Key Features and Specifications

• Connection: 4″ (100 mm) cast iron to 4″ (110 mm) uPVC / PVC-U plastic drainage pipe
• Body material: Flexible rubber / thermoplastic elastomer compound for resilience and ground movement tolerance
• Fixings: Stainless steel worm-drive jubilee clips supplied as standard for a corrosion-resistant, leak-proof seal
• Application type: Non-pressure underground drainage and soil pipe jointing
• Manufactured: UK-made at Kalsi’s Birmingham extrusion plant under ISO 9001 Quality Management System
• Kitemark certified: Kalsi Aquaflow products carry BSI Kitemark certification
• Accommodates: Slight variations in outside diameter between pipe manufacturers and materials
• Installation: Tool-light fit — tighten clips with a screwdriver or worm-drive driver; no adhesives required

Applications

• Connecting new uPVC underground drainage to existing cast iron soil stacks or drain runs
• House extension drainage tie-ins where cast iron is already in the ground
• Drain repair and renovation — replacing a damaged cast iron section with plastic pipe
• Loft conversions and bathroom additions requiring a new soil pipe connection to an old cast iron stack
• Residential and light commercial drainage refurbishment projects

Why Choose This Product

Kalsi Group is a trusted UK manufacturer with over 30 years of experience in drainage and building plastics. The Aquaflow flexible adaptor is designed specifically for the imperial-to-metric pipe size challenge common in UK renovation work, where cast iron and plastic pipes rarely share identical outside diameters. The rubber body flexes with normal ground movement, the stainless steel clips resist corrosion underground, and the straightforward installation reduces labour time on site. Trade quantities are welcome.

Delivery in and Around London

This product is available for delivery across London boroughs including Croydon, Lewisham, Southwark, Camden, and Hackney, as well as Greater London areas such as Enfield, Bexley, Redbridge, and Barnet. We also supply to the surrounding counties of Kent, Essex, Surrey, and Hertfordshire. Orders are dispatched promptly and trade quantities are welcome — contact us for bulk pricing and availability.