1" G Thread (BSPP) Female to 1 1/4" NPT Male Brass Adapter with Washer

This adapter connects a 1" G (BSPP) female thread to a 1 1/4" NPT male thread, so you can join two different plumbing standards without replacing existing pipework. It's built from lead-free brass and ships with a washer, since G (BSPP) threads are parallel and seal with a washer rather than tape or sealant.

What It Connects

• Female side: 1" G (BSPP) — parallel thread
• Male side: 1 1/4" NPT — tapered thread

Key Features

• Lead-free brass construction, safe for potable water
• Washer included for a proper seal on the G thread side
• Simple screw-in installation, no special tools required

Common Uses

• Shower systems and larger-diameter supply line connections
• Hose-to-fixture adapters
• Fixture retrofits where thread types don't match

Specifications

Package Includes

• 1 x Adapter, 1" G Female to 1 1/4" NPT Male
• 1 x Washer

Installation Notes

1. Confirm your existing fittings match: 1" G female on one side, 1 1/4" NPT male on the other.
2. Seat the included washer on the G thread side before threading — this is what creates the seal.
3. Hand-tighten first, then snug with a wrench sized to the hex flats. Don't overtighten.
4. Plumber's tape can be used on the NPT male side if needed.
5. Run water briefly and check the joint before finishing the install.

FAQ

What's the difference between G thread and NPT thread?
G thread (BSPP) is parallel and seals with a washer. NPT is tapered and seals by compression. This adapter connects the two.

Do I need plumber's tape?
The G thread side seals with the included washer. Tape is optional on the NPT male side.

Is this safe for drinking water?
Yes, it's lead-free brass, rated for potable water use.

Will this fit my shower system?
If your shower system uses a 1" G female connection and needs to connect to 1 1/4" NPT, yes.

Is this the same as the 3/4" NPT version?
No — this adapter's male end is 1 1/4" NPT, a larger thread than the 3/4" NPT version. Check your existing fitting size before ordering.