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.

Steven · Answer

Oh dear 1-1/2" pipe is ready BIG for a shower head. There must have a reducer at the end to connect the shower head if the shoer head is standard. If there is, you do not need to worry about it as bigger pipe supply more water (higher pressure) for your shower time.

Otherwise, my suggestion is get a plumber to replace it to normal 1/2" (15mm) one as you might find it is very difficult to get a 1-1/2" (40mm) connecting shower head in the market.

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

Azeem · Answer

Not necessarily. In most cases, you won’t need the pipe changing. It’s usually just a matter of identifying the correct fitting or buying an adapter if it’s a proprietary connection.

Rain Shower Head

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