SML Below Ground

Harmer SML Below Ground extends the performance benefits of cast iron into buried drainage applications, providing a durable solution for underground foul and stormwater networks. The system comprises pipes, fittings, bends, junctions and access components designed to withstand external loads and challenging site conditions. Offering excellent resistance to impact, fire and environmental exposure, SML Below Ground delivers a long service life with minimal maintenance requirements. Its robust construction makes it particularly suitable for commercial developments, public buildings and infrastructure projects where reliability and durability are paramount.

Explore Products Within This Range

Complete below-ground soil and waste drainage system.
Allows direct connection from soil stack to drain and sewer in accordance with SFA requirements.
Comprehensive range of pipes, fittings and access chambers.
Pipes available in standard 3-metre lengths.
Diameter range available from 100mm to 400mm.
Choice of stainless steel or ductile cast iron couplings.
Available with round, square and rectangular inspection chambers.
Inspection chambers available for 100mm and 150mm pipe connections with 45° branch arms.
Manufactured and tested to BS EN 877.
CE Mark compliant in accordance with the Construction Products Regulation.
Kitemark certified to BS EN 877.
Robust, lightweight, strong and durable construction.
Excellent acoustic performance, tested to BS EN 14366:2004.
Non-combustible material eliminates the need for fire protection collars.
High tensile strength and excellent load-bearing capability.
Secure socketless fixing between pipes and fittings.
Quick and easy installation without specialist equipment.
Fully compatible with Harmer SML above-ground systems.
Thermal spray zinc and epoxy coatings provide long-term corrosion protection.
Cast iron is 100% recyclable.

Below-ground soil and waste drainage systems
Commercial developments
Residential developments
Apartment buildings
Education facilities
Healthcare buildings
Hotels and leisure facilities
Retail and shopping centres
Industrial developments
Public sector buildings
Mixed-use developments
Infrastructure projects
Refurbishment and retrofit projects
New-build construction projects
Direct drain-to-sewer connection applications

Harmer SML Below Ground Drainage Systems are advanced cast iron pipework solutions designed to provide reliable below ground drainage from soil stack to sewer connection. Manufactured and tested in accordance with BS EN 877, the system combines the proven performance of cast iron with modern dry-jointed installation methods to deliver a durable and efficient drainage solution for a wide range of building applications.

The system comprises a complete range of pipes, fittings, couplings and inspection chambers, enabling comprehensive below ground drainage installations. Pipes are available in standard 3-metre lengths and a range of diameters, allowing the system to accommodate varying project requirements. Round, square and rectangular inspection chambers are available for 100mm and 150mm connections, with branch arm configurations designed to comply with BS EN 12056-4.

Harmer SML Below Ground enables direct connection from soil stack to drain and sewer, providing a fully integrated drainage solution. Compatible with the Harmer SML Above Ground system, it allows continuity throughout the building drainage network using a single cast iron specification. Secure socketless joints are achieved through stainless steel or ductile iron couplings, ensuring dependable performance without the need for specialist installation equipment.

Manufactured from grey cast iron to DIN 1691 standards, the system offers exceptional tensile strength, load-bearing capability and resistance to accidental damage. Thermal spray zinc coatings and epoxy protective finishes provide long-term corrosion resistance while reducing maintenance requirements throughout the life of the installation. The non-combustible nature of cast iron also contributes to enhanced fire performance.

Suitable for residential, commercial, healthcare, education and public sector developments, Harmer SML Below Ground Drainage Systems provide a durable, sustainable and fully certified drainage solution. Their combination of strength, longevity, installation efficiency and regulatory compliance makes them ideal for modern underground drainage applications.