Garden Hose Thread
Pipe Threads · 7 specs
Direct Answer
Garden Hose Thread (GHT) is the standardized North American outdoor water coupling governed by ANSI/ASME B1.20.7. Specified as 3/4"-11.5 NH, it features a straight, non-tapered thread with a 1.0625-inch (27.0 mm) major diameter that seals via axial compression against a flat rubber washer inside the female swivel coupling.
Source: ANSI/ASME B1.20.7-1991 (R2018) · Last reviewed Aug 28, 2026
Specs
| Standard Governing Body | ANSI / ASME B1.20.7 |
| Thread Designation | 3/4"-11.5 NH (National Hose) |
| Major Diameter (Male Outer ø) | 1.0625 inches (27.0 mm) |
| Thread Pitch / TPI | 11.5 TPI (2.209 mm pitch) |
| Thread Form & Flank Angle | 60° American National straight parallel thread |
| Sealing Mechanism | Flat elastomeric washer compressed in female swivel seat |
| Operating Water Pressure | 40–80 PSI typical residential (up to 150 PSI burst) |
Parallel Thread Mechanics and Washer Compression
Unlike tapered pipe threads (such as NPT), GHT is a straight parallel thread (0° taper). The threads perform solely as a mechanical clamp to pull the male nose flat against a rubber or silicone O-ring/washer seated inside the female swivel coupling. Hand-tightening or gentle quarter-turn wrench torque provides complete water sealing up to standard municipal pressures (60–80 PSI).
GHT vs 3/4-inch NPT Distinction
A common plumbing error is attempting to screw a 3/4-inch NPT pipe fitting directly into a 3/4-inch GHT garden hose outlet. While both share the same nominal 3/4-inch designation and 11.5 TPI pitch:
- GHT has a fixed outer diameter of 1.0625 in (27.0 mm) and parallel walls.
- NPT has a tapered outer diameter (1.050 in at small end to 1.060 in at gauge plane).
An NPT fitting will thread approximately 1 to 2 turns before binding without compressing the internal washer, resulting in high-pressure spraying. Dedicated 3/4" GHT to 3/4" NPT brass adapters are required to transition between garden hoses and rigid pipework.