Wrong thread type on one side? This adapter solves it. The 1" G (BSPP) female to 3/4" NPT male brass adapter bridges two of the most common plumbing standards — parallel G thread on one end, tapered NPT on the other — without cutting into existing pipework or replacing fixtures.
Made from lead-free brass and rated for potable water. A washer ships in the box because G (BSPP) threads seal against a washer face, not thread tape — so everything you need for a proper install is already included.
Thread Connections
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Female side: 1" G (BSPP) — parallel thread, seals with washer
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Male side: 3/4" NPT — tapered thread, seals by compression
Where This Gets Used
- Shower systems and shower arm connections where thread standards don't match
- Hose-to-fixture hookups requiring a G to NPT conversion
- Fixture retrofits on imported equipment with BSPP threads connecting to US standard NPT lines
- Irrigation and water supply lines mixing British and American fittings
Features
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Lead-free brass — safe for drinking water and potable water systems
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Washer included — correct seal on the G thread side, right out of the box
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Compact build — 1¼" overall length fits tight spaces without extension
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Screw-in install — hand tools only, no special equipment needed
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1⅜" hex — standard wrench size for a clean final tighten
Specifications
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SKU: CSSL56160940
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Material: Lead-Free Brass
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Finish: Brass
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Female Thread: 1" G (BSPP) — parallel
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Male Thread: 3/4" NPT — tapered
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Overall Length: 1¼" (34mm)
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Male Thread Diameter: 5/8" (Ø19mm)
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Male Thread Length: ½" (14mm)
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Hex Size (Female End): 1⅜" (38mm)
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Installation Method: Screw-In
Package Includes
- 1 × Adapter — 1" G Female to 3/4" NPT Male
- 1 × Washer
Installation
- Check both sides — you need a 1" G female connection on one end and 3/4" NPT male on the other.
- Place the included washer on the G thread (female) side before threading — this creates the seal.
- Hand-tighten first, then finish with a 1⅜" wrench. Do not overtighten.
- Plumber's tape can be applied to the NPT male side as an extra precaution if needed.
- Turn the water on briefly and check the joint before closing up the installation.
FAQ
Q) What's the difference between G (BSPP) and NPT thread?
G thread is parallel — the diameter stays constant along the thread. NPT is tapered — it gets slightly narrower toward the end and seals by compression. This adapter connects the two standards.
Q) Do I need plumber's tape?
Not on the G thread side — the washer handles that seal. Tape is optional on the NPT male side.
Q) Is this safe for drinking water lines?
Yes. Lead-free brass construction, rated for potable water use.
Q) What wrench size fits this?
The hex across the female end measures 1⅜" (38mm).
Q) Will this work with my shower system?
If your shower system has a 1" G female outlet and you're connecting to a 3/4" NPT male fitting, this is the right adapter.
Q) Does G thread need sealant?
No — G (BSPP) thread seals against a flat face using a washer, not sealant or tape. The washer is included in the package.
