Trilateral® SST Underdrain
The Trilateral® SST is Roberts Filter Group’s premium stainless steel underdrain system, designed to eliminate the common failure points of traditional plastic or concrete solutions. With industry-leading strength, precision construction, and field-verified performance, the Trilateral® SST delivers consistent backwash distribution and extended filter life — making it ideal for municipal and industrial filtration systems.
Why Choose Trilateral® SST?
No Grout Failures
Grout is a leading cause of underdrain failure. The Trilateral® SST is mechanically secured to the filter floor with verified pull-out strength, eliminating grout from the equation and ensuring long-lasting reliability.
Double the Thickness
Built with a 14-gauge stainless steel outer shell — literally twice as thick as some competitors — the Trilateral® SST withstands pressure surges, water hammer, and heavy service environments.
3D Media Retention
A custom “3D” louver design distributes air and water evenly during backwash. Supported on three sides, the louvers resist deformation from water pressure or accidental impacts, ensuring consistent performance over time.
Seam-Welded Construction
The Trilateral® SST is fully seam welded around its exterior shell, eliminating the weak points of spot welds. This ensures strength, prevents leaks, and protects against media intrusion.
Ideal Applications
Municipal drinking water filtration
Biologically active filters
Industrial water treatment systems
Retrofit or replacement of failing plastic or concrete underdrains
Benefits
Longest service life in its class
Eliminates grout failure risks
Withstands demanding operating conditions
Superior air and water distribution for efficient backwash
OEM-quality installation and lifecycle support
Lifecycle Support
Roberts Filter Group backs every Trilateral® SST installation with full lifecycle services — from inspections and audits to turnkey installation, retrofits, and media changeouts.
Looking for the strongest and most reliable underdrain solution?
The Trilateral® SST delivers unmatched performance, durability, and peace of mind.
