Rain Shower Head

Question

Hi,
I recently look at changing the head of our ceiling mounted shower head and found that the pipe is 1.5" instead of the BSP1/2 (looking at google). 

Is there a reason why the pipe would be that wide? 
Or should I look at getting a plumber back to change it to the standard?

Bradley · Accepted Answer

Why you might see a 1.5” pipe at the shower arm

A ceiling‑mounted shower head normally connects to a ½” BSP male thread (about 21mm outside diameter).
So when you see something that looks like 1.5 inches, it’s almost never the actual water pipe size.

Here are the usual explanations:

1. It’s not the pipe — it’s the decorative “drop arm” or cover plate

Ceiling showers often use a large diameter arm for aesthetics.
Inside that arm is a standard ½” BSP female thread.

The outside can easily measure 1.25”–1.5”, but the connection is still standard.

2. You might be measuring the outside of a fitting, not the thread

Plumbing sizes are always measured by the internal bore, not the outside diameter.
A ½” BSP fitting often measures around 20–25mm externally, which can look much bigger.

3. Some installers use a reducing bush or oversized pipe for rigidity

Especially with ceiling drops, a wider pipe or sleeve is used to:

• keep the shower arm rigid
• hide the actual water feed
• allow for a decorative finish

But the threaded end is still ½” BSP.

---

🛠 Should you get a plumber to change it?

Probably not.
Unless the actual threaded connection is not ½” BSP (which would be very unusual in the UK), there’s no need to modify anything.

Before calling anyone back, check:

✔ Does the shower arm have a removable end?

Most ceiling shower arms unscrew, revealing a ½” BSP male thread.

✔ Does your new shower head have a ½” BSP female connection?

Almost all UK shower heads do.

If both are true, everything will fit.

---

🔍 When would you actually need a plumber?

Only if:

• the installer used a genuinely non‑standard thread (rare), or
• the pipe is a custom size from a foreign system (even rarer), or
• the arm is welded or fixed in a way that prevents swapping the head

Ola · Answer

Hi Rob.

My name is Ola.

This is normal.  All that is needed is a right fitting to connect to the 15mm of your shower head.

Dan · Answer

You can get a iron fitting that will reduce the size of threaded end and then you can put a standard half inch head replacing the existing shower outlet
Any plumber should be able to find a fitting to make this happen. I hope this sort of help.

Curtis · Answer

That does sound unusual at first—but it’s probably not what it looks like.
🔍 Most likely explanation
A true 1.5 inch pipe feeding a shower head is extremely unlikely in a domestic setup. Standard shower connections in the UK are almost always:
1/2" BSP (by far the most common)
Sometimes 3/4" BSP on high-flow systems
So what you’re seeing is usually one of these situations:
🧱 1. It’s a shroud or cover, not the actual pipe
Ceiling-mounted showers often have a large chrome tube for appearance. Inside that is a much smaller pipe.
👉 The outer part might measure ~1.5", but the actual threaded connection at the end is still 1/2" BSP.
🔩 2. You’re measuring the outside diameter
Pipe sizing is confusing because:
“1/2 inch BSP” does not mean the pipe measures 1/2 inch across
The outside of fittings can look much bigger
So it can easily look like 1"+ when it’s actually standard.
🚿 3. It could be a fixed ceiling arm
Some rainfall shower setups use:
A fixed ceiling arm with a built-in connector
The head screws onto an internal thread or hidden fitting
⚠️ When it might be non-standard
Less common, but possible:
High-end or imported systems using non-UK threads
Custom installations with larger bore pipe for high flow
🛠️ What you should do next
Before calling a plumber:
Check the very end where the head attaches
Is there a visible thread?
Does it look like a standard screw fitting inside?
Try removing the shower head fully
You may find a normal 1/2" BSP male thread hidden inside
Take a photo or measure the thread itself (not the outer pipe)
💡 Should you change it?
👉 No need to change anything unless:
It genuinely isn’t compatible with standard shower heads
Or you want to replace the whole arm/ceiling fitting
In most cases, you’ll just need:
The right adapter, or
A compatible shower head
✔️ Bottom line
It’s almost certainly not a 1.5" supply pipe—just a larger outer casing or misleading measurement. Don’t rip it out yet.

Mihai · Answer

For a standard 10-unit kitchen, expect £800 to £2,000 for doors and drawer fronts.

Shajim · Answer

Can be easily fixed try getting yourself a reducer to fit on to your bsp

Rain Shower Head

Follow Us

Cookies

Manage Cookies

Essential cookies

Analytics & Tracking

Advertising