Angle Valve or Concealed Valve? Valve Types

"Should we fit an angle valve under the basin? A concealed valve for the shower? And is it half an inch or 3/4?" These are the questions a plumber asks with every bathroom or kitchen fit-out, and the wrong valve, or a valve installed the wrong way, is one of the most common causes of leaks and broken tiles after finishing. In this guide from Tawredaat (توريدات), an electrical and finishing materials store in Cairo and Giza, we explain the types of water valves, which type each spot in your home needs, the sizes, and how to recognise a good valve, with information from manufacturers' catalogs and international thread standards.

What are the types of water valves in the home?

• Angle valve: a small angle-shaped valve that comes out of the wall and connects with a flexible hose to the appliance (mixer, toilet cistern, water heater). Its face is visible and it can be replaced without breaking anything.
• Concealed stop valve: the valve body is fitted inside the wall on the pipe, and after finishing only the trim (the cover plate and handle) is visible. It is used to shut off a water line, such as the shower line or the whole bathroom line.
• Built-in mixer body: installed much like a concealed valve, but this is a body on which a concealed shower or bath mixer is mounted, like the Roca RocaBox, which Roca says is completed with a thermostatic mixer or a single-lever built-in mixer.
• Main valve (ball valve): on the water inlet to the flat or at the start of the line. It shuts off the water to the whole home, and it operates with a small turn of the handle.

Angle valve, concealed valve or main valve: what's the difference?

Which valve does each spot in the home need?

• ✔ The simple rule: every appliance gets its own angle valve, so if one thing leaks you shut off only that, and everything else keeps working.
• ✔ A concealed valve is useful if you want to shut off the shower line or the whole bathroom without shutting off the flat.

Valve size: half an inch or 3/4?

The valve sizes we talk about (1/2" and 3/4") are nominal thread sizes, not the actual diameter in millimetres. The parallel thread used in water and hose connections is defined in the international standard ISO 228-1 (written as G1/2 and G3/4):

• ✔ So a "half-inch" valve has an external thread diameter of about 21 mm, and a "3/4" one about 26.4 mm. If you are comparing an old valve with a new one, measure this thread.
• ✔ The ISO 228 (G) thread is called in the standard a "pipe thread where pressure-tight joints are not made on the threads", meaning the seal is made by a washer or gasket. The ISO 7 (R / Rp) thread, on the other hand, is the tapered thread where the seal is made on the thread itself with a sealing material.
• ✔ In the GROHE catalog, for example, the 22037 angle valve has a 1/2" inlet from the wall and a 3/8" outlet with a 10 mm compression nut. So make sure the mixer or cistern hose fits the outlet of the valve you choose.
• ✔ The angle valves available on Tawredaat from Ideal Standard and Plaza (Lotus and Magic) have 1/2" in their names, and the Roca Universal built-in body has a 1/2" connection according to Roca's specifications.
• ⚠ The size of the main valve follows the diameter of the water inlet pipe; the plumber determines it from the existing pipe in your home.

How do you recognise a good valve?

1. Material

• ✔ Choose chrome-plated brass. The Plaza Silver and Plaza Magic product pages say they are solid brass, and the Ideal Standard G4308AA is brass with a chrome finish.
• ⚠ Thin chrome, or a valve that feels very light in the hand, is usually a sign of a weak body.

2. Cartridge type: ceramic or washer?

• ✔ Ceramic disc: according to tap maker Caple, a ceramic disc valve goes from on to off in a quarter turn, and is more reliable than a washer valve.
• ✔ Compression / washer valve: needs several turns to open and close, and the washer wears out over time so the valve starts to drip; the fix is replacing the washer (Caple).
• ⚠ The same source says ceramic discs are more sensitive to limescale, sediment and grit in the water, so have the plumber flush the pipes (run water through them) before fitting valves and mixers.

3. Thread and finish

• ✔ The thread should be clean, straight and free of burrs, and match the pipe size (1/2" with 1/2").
• ✔ The cover plate (trim) should sit flush on the wall and hide the outlet opening.

How deep is a concealed valve installed in the wall?

This is the most important question for a concealed valve and a built-in mixer body, because the depth is set before plaster and tiles, and if it is wrong the trim won't fit or will stick out.

• ✔ Every built-in body has an installation depth range in the manufacturer's guide. For example, the GROHE Rapido SmartBox has an installation depth range of 75 – 105 mm, and 1/2" connections.
• ✔ The plumber must account for the thickness of the plaster + tile adhesive and tiles that will go over the body, and fix the body so the finished wall surface falls within that range. The installation guide shows where the depth is measured from.
• ✔ If the body was set deeper than needed, some manufacturers make extension kits for some bodies (Roca, for example, has a 20 mm Round extension kit), but these only work with specific models.
• ⚠ Don't buy the built-in body from one brand and the concealed mixer from another. Roca publishes the list of mixers that fit the RocaBox, so choose both together from the same manufacturer.

Common mistakes that cause leaks

• ⚠ Installing the concealed valve at the wrong depth: either the trim won't fit, or you have to break the tiles. Stick to the depth range in the catalog.
• ⚠ One angle valve for several appliances, or no valve at all: any leak forces you to shut off the whole flat.
• ⚠ Overtightening the connection: overtightening damages the thread or cuts the washer, and with a G thread the seal is made by the washer anyway, not by how hard you tighten.
• ⚠ Teflon in the wrong place: a connection that seals with a washer (G thread) doesn't need Teflon on the thread, while the tapered thread (R) is the one that seals with a sealing material on the thread. The plumber can tell the difference from the connection type.
• ⚠ A hidden main valve behind a cabinet or tiles: in an emergency you need to reach it in seconds.
• ⚠ Fitting valves without flushing the pipes: leftover sand and limescale damage the ceramic disc from day one.

Finally, the final installation and the choice of sizes should be left to a skilled plumber / qualified plumbing technician who sees the pipes on site and follows each product's installation guide.

Valves available on Tawredaat

These models are available to buy now on the site:

• Angle valves: Ideal Standard 1/2" chrome angle valve G4308AA · Ideal Standard 1/2" chrome angle valve G4303AA · Plaza Lotus 1/2" · Plaza Magic 1/2" · Plaza Silver · Plaza Fayrouz
• Concealed valves: Plaza Galaxy concealed valve · Plaza Style concealed valve
• Built-in bodies for mixers: Roca RocaBox Universal for shower and bath · Roca Universal built-in body

You can see every model in our water valves collection and concealed valves and bodies. And if you are also choosing a mixer, see our guide to choosing a bathroom and kitchen mixer, and if you are finishing the shower, see our shower guide: rain shower or regular.

Frequently asked questions

Angle valve or concealed valve: which is better?
They don't replace each other. An angle valve is for each appliance under the basin and beside the toilet cistern and water heater, and a concealed valve is for the shower or bathroom line inside the wall. Most bathrooms need both.

What size is an angle valve?
The common size is 1/2" (half inch), which is the size of all the angle valves available on Tawredaat. The valve's outlet to the hose can differ (on the GROHE 22037, for example, it is 3/8"), so make sure the hose fits it.

What does a half-inch valve mean? Is its diameter 12.7 mm?
No. "Half inch" is the name of the thread size. Under ISO 228-1, a G1/2 thread has an external diameter of about 20.955 mm and G3/4 about 26.441 mm, both with 14 threads per inch.

How deep is a concealed valve installed?
It depends on the built-in body itself. The GROHE Rapido SmartBox, for example, has an installation depth range of 75 – 105 mm. The plumber accounts for the plaster and tiles and follows the installation guide.

Is a ceramic valve cartridge better than a washer?
Ceramic opens and closes in a quarter turn and is more reliable, while the washer wears out over time and drips (Caple). But ceramic is more sensitive to limescale and grit, so the pipes must be flushed before installation.

Can I fit a concealed mixer from one brand on a body from another brand?
Better not. The built-in body and the concealed mixer are designed together, and Roca, for example, publishes the list of mixers that fit the RocaBox.

About Tawredaat: Tawredaat (توريدات) is an Egyptian supplier of electrical and finishing materials and sanitary ware, serving homeowners, companies and contractors in Cairo and Giza. Questions? See our FAQ.