GHT vs. NPT: Why "3/4 Inch" Doesn't Always Mean 3/4 Inch

It's one of the most common stumbling blocks when connecting a float valve: you have a 3/4" valve and a 3/4" fitting, and they won't seal. Nothing is defective. The two parts are simply using different threads that happen to share a name.

Two Threads, One Nominal Size

GHT is garden hose thread. It's a straight thread that seals with a rubber washer. NPT is the tapered pipe thread used in plumbing. It seals as the threads wedge together, usually with thread tape or sealant.

Both are called "3/4 inch," but that size is a nominal label rather than a measurement, and the two threads have different pitches and shapes. They can start to engage, which is what makes the mismatch so easy to miss, but they won't seal properly, and forcing them can damage the threads. Always match the thread type, not just the size number.

What Thread Does a Jobe Valve Use?

The tails on every Jobe valve line sold in North America are male NPT. That means they connect to a female NPT fitting on your supply line. If your plumbing ends in a male fitting, you'll need a female coupling or adapter to join the two. BSP threads are available by special order (they're more common in overseas markets); contact us if you need them.

Connecting a Garden Hose

A garden hose is GHT, and a Jobe valve tail is NPT, so a hose can't thread straight onto the valve. It needs an adapter. Two Jobe adapters cover most hose setups:

• The Tank Mount Adapter (ADF210) fits through a standard 2" drain hole and has a 3/4" female garden hose connection for your supply, a 1" male NPT tank connection, and a 3/4" female NPT connection for the valve.
• The ADF110 valve-to-garden-hose adapter is for connecting a valve to a hose directly.

Not sure which of the two you need? Our ADF110 vs. ADF210 comparison walks through it.

A Four-Question Checklist Before You Order

1. What thread is on the supply end? A hose is GHT. Pipe and plumbing fittings are normally NPT.
2. Is it male or female? The valve tail is male, so it needs a female fitting on the other side.
3. What size is it? Match the inlet to your supply plumbing. Your flow is always limited by the smallest pipe in the system.
4. Long tail or short tail? That depends on how the valve mounts, not on the thread. See our tail selection guide.

Still Unsure?

If you can describe what's on your supply line, we can help you match it. Contact us with a photo or the fitting details and we'll point you to the right part.