Watts-SF-40 Watts String Wound Cartridge Standard 40" in
Watts SF-40 String Wound Sediment Cartridge 40-Inch
Industrial-length polypropylene string wound filter for whole house and commercial applications requiring extended sediment capacity
String wound construction for heavy sediment loads
Precision Wound Design
Polypropylene string wound tightly around a core creates gradient density filtration—outer layers catch larger particles, inner layers trap finer sediment down to 1 or 5 micron
Zero Media Migration
No loose fibers or carbon fines to contaminate downstream equipment. The wound construction stays intact throughout the filter life, critical for RO pre-filtration
Chemical Resistance
100% polypropylene construction resists acids, alkalis, and organic solvents. Food grade materials meet FDA requirements for potable water and beverage applications
Extended Capacity
40-inch length provides significantly more surface area than standard 10" or 20" cartridges, extending service life and reducing change-out frequency in high-flow systems
Watts SF-40 Technical Details
| Dimensions | 2.5" diameter × 40" length |
| Micron Rating | 1 micron or 5 micron (verify before ordering) |
| Media | Polypropylene string wound |
| Temperature Range | Up to 140°F (60°C) |
| Pressure Rating | 40 PSI maximum |
| End Cap Material | Polypropylene |
| Certifications | FDA compliant for food and beverage contact |
Fits Watts FlowMax and standard 40-inch housings
This cartridge is designed for Watts FlowMax 40-inch filter housings and other proprietary whole house systems that accept 40" sediment filters with a 2.5" outer diameter. Commonly used as pre-filtration for commercial reverse osmosis systems, light industrial water treatment, well water applications, and large residential whole house systems requiring extended sediment capacity. Verify housing compatibility before ordering—40-inch cartridges require specialized tall housings not common in residential applications.
Replacement schedule based on water quality
Heavy Sediment
Well water with visible particulate, high turbidity, or iron content. Monitor pressure drop—replace when flow decreases noticeably
Moderate Sediment
Municipal water with occasional turbidity or as RO pre-filter in commercial applications. Replace based on pressure differential across housing
Light Sediment
Clean municipal water or light-duty applications. Even with minimal visible sediment, replace annually to prevent bacterial growth in trapped particles
No Leachables
Pure polypropylene construction contains no binders, adhesives, or processing aids that could contaminate filtered water
Temperature Stable
Maintains structural integrity and filtration performance in water up to 140°F without fiber release or dimensional changes
Protected Packaging
Individually sealed in poly bags to maintain cleanliness from manufacturing through installation
Gradient Density
Wound pattern creates denser filtration toward the core, maximizing dirt-holding capacity while maintaining flow rate
Watts SF-40 String Wound Sediment Cartridge 40-Inch
Industrial-length polypropylene string wound filter for whole house and commercial applications requiring extended sediment capacity
String wound construction for heavy sediment loads
Precision Wound Design
Polypropylene string wound tightly around a core creates gradient density filtration—outer layers catch larger particles, inner layers trap finer sediment down to 1 or 5 micron
Zero Media Migration
No loose fibers or carbon fines to contaminate downstream equipment. The wound construction stays intact throughout the filter life, critical for RO pre-filtration
Chemical Resistance
100% polypropylene construction resists acids, alkalis, and organic solvents. Food grade materials meet FDA requirements for potable water and beverage applications
Extended Capacity
40-inch length provides significantly more surface area than standard 10" or 20" cartridges, extending service life and reducing change-out frequency in high-flow systems
Watts SF-40 Technical Details
| Dimensions | 2.5" diameter × 40" length |
| Micron Rating | 1 micron or 5 micron (verify before ordering) |
| Media | Polypropylene string wound |
| Temperature Range | Up to 140°F (60°C) |
| Pressure Rating | 40 PSI maximum |
| End Cap Material | Polypropylene |
| Certifications | FDA compliant for food and beverage contact |
Fits Watts FlowMax and standard 40-inch housings
This cartridge is designed for Watts FlowMax 40-inch filter housings and other proprietary whole house systems that accept 40" sediment filters with a 2.5" outer diameter. Commonly used as pre-filtration for commercial reverse osmosis systems, light industrial water treatment, well water applications, and large residential whole house systems requiring extended sediment capacity. Verify housing compatibility before ordering—40-inch cartridges require specialized tall housings not common in residential applications.
Replacement schedule based on water quality
Heavy Sediment
Well water with visible particulate, high turbidity, or iron content. Monitor pressure drop—replace when flow decreases noticeably
Moderate Sediment
Municipal water with occasional turbidity or as RO pre-filter in commercial applications. Replace based on pressure differential across housing
Light Sediment
Clean municipal water or light-duty applications. Even with minimal visible sediment, replace annually to prevent bacterial growth in trapped particles
No Leachables
Pure polypropylene construction contains no binders, adhesives, or processing aids that could contaminate filtered water
Temperature Stable
Maintains structural integrity and filtration performance in water up to 140°F without fiber release or dimensional changes
Protected Packaging
Individually sealed in poly bags to maintain cleanliness from manufacturing through installation
Gradient Density
Wound pattern creates denser filtration toward the core, maximizing dirt-holding capacity while maintaining flow rate
Original: $28.07
-65%$28.07
$9.82Description
Watts SF-40 String Wound Sediment Cartridge 40-Inch
Industrial-length polypropylene string wound filter for whole house and commercial applications requiring extended sediment capacity
String wound construction for heavy sediment loads
Precision Wound Design
Polypropylene string wound tightly around a core creates gradient density filtration—outer layers catch larger particles, inner layers trap finer sediment down to 1 or 5 micron
Zero Media Migration
No loose fibers or carbon fines to contaminate downstream equipment. The wound construction stays intact throughout the filter life, critical for RO pre-filtration
Chemical Resistance
100% polypropylene construction resists acids, alkalis, and organic solvents. Food grade materials meet FDA requirements for potable water and beverage applications
Extended Capacity
40-inch length provides significantly more surface area than standard 10" or 20" cartridges, extending service life and reducing change-out frequency in high-flow systems
Watts SF-40 Technical Details
| Dimensions | 2.5" diameter × 40" length |
| Micron Rating | 1 micron or 5 micron (verify before ordering) |
| Media | Polypropylene string wound |
| Temperature Range | Up to 140°F (60°C) |
| Pressure Rating | 40 PSI maximum |
| End Cap Material | Polypropylene |
| Certifications | FDA compliant for food and beverage contact |
Fits Watts FlowMax and standard 40-inch housings
This cartridge is designed for Watts FlowMax 40-inch filter housings and other proprietary whole house systems that accept 40" sediment filters with a 2.5" outer diameter. Commonly used as pre-filtration for commercial reverse osmosis systems, light industrial water treatment, well water applications, and large residential whole house systems requiring extended sediment capacity. Verify housing compatibility before ordering—40-inch cartridges require specialized tall housings not common in residential applications.
Replacement schedule based on water quality
Heavy Sediment
Well water with visible particulate, high turbidity, or iron content. Monitor pressure drop—replace when flow decreases noticeably
Moderate Sediment
Municipal water with occasional turbidity or as RO pre-filter in commercial applications. Replace based on pressure differential across housing
Light Sediment
Clean municipal water or light-duty applications. Even with minimal visible sediment, replace annually to prevent bacterial growth in trapped particles
No Leachables
Pure polypropylene construction contains no binders, adhesives, or processing aids that could contaminate filtered water
Temperature Stable
Maintains structural integrity and filtration performance in water up to 140°F without fiber release or dimensional changes
Protected Packaging
Individually sealed in poly bags to maintain cleanliness from manufacturing through installation
Gradient Density
Wound pattern creates denser filtration toward the core, maximizing dirt-holding capacity while maintaining flow rate
