The Watts BB-NUT (BBH Nut) is a genuine replacement cap nut designed specifically for Big Bubba whole house filter housings, ensuring a secure seal and proper system operation. This black threaded nut (part #21 in the Big Bubba assembly diagram) provides reliable housing closure for 10-inch and 20-inch Big Bubba systems.
TECHNICAL DETAILS
Replacement Cap Nut Specifications
| Manufacturer | Watts |
| Model Number | BB-NUT (BBH Nut) |
| Color | Black |
| Component Type | Cap Nut / Threaded Closure |
| Assembly Reference | Part #21 (Big Bubba Diagram) |
| Material | Durable Plastic Composite |
| Thread Type | Standard Big Bubba Threading |
COMPATIBILITY & APPLICATIONS
System Fit
This cap nut is engineered for use with Watts Big Bubba whole house filter housings, including both 10-inch and 20-inch models. It threads onto the housing head to secure the sump and maintain system pressure integrity. Compatible with standard Big Bubba configurations used in residential and light commercial whole house filtration applications. Verify part compatibility by referencing the Big Bubba assembly diagram where this component is identified as part #21.
💧 Keep a spare BB-NUT on hand during routine filter changes—having the correct replacement part available prevents delays if threads wear or the nut cracks during maintenance.
