What is a monobloc tap, and which basin tap should I choose?
Monobloc, pillar and three-hole taps explained, the pressure rating that decides whether a tap works on your system, and the tail type that decides how hard it is to fit.
- Difficulty
- beginner
- Time
- 15 min
- Read
- 4 min
Short answer
A monobloc is a single-hole mixer that blends hot and cold inside one body — the standard modern basin tap. Pillar taps are a separate hot and cold in two holes. Whichever you choose, the two things that actually matter are that the tap suits your water pressure and that the number of holes in your basin matches the tap.
Basin taps are almost all half-inch BSP and almost all fit almost all basins, which makes the choice feel free and hides the two ways it goes wrong: buying a tap designed for mains pressure and fitting it to a gravity-fed system where it trickles, and buying a three-hole mixer for a one-hole basin. Both are settled by two minutes of checking.
Step by step
- Count the holes in your basin.One hole takes a monobloc. Two holes take a pair of pillar taps. Three holes take a mixer with a separate spout and two handles. No holes means a wall-mounted or worktop-mounted tap and pipework in the wall. You cannot invisibly fill a hole in ceramic, so the tap has to use the holes you have.
- Understand the monobloc.A single body through one hole, blending hot and cold internally and delivering mixed water from one spout. Either a single lever that moves for flow and rotates for temperature, or two small handles on one body. It is the modern default because it is easy to use, easy to fit and needs only one hole.
- Understand pillar taps.Separate hot and cold taps in two holes, each delivering its own water. Traditional in appearance, entirely reliable, and the reason older UK basins have you washing in water that is either too hot or too cold. Still the right answer aesthetically in a period bathroom.
- Find out what pressure you have.This is the decision that actually matters. Mains-fed hot water — a combi boiler or an unvented cylinder — gives you good pressure and almost any tap works. Gravity-fed hot water from a cylinder with a cold tank in the loft gives very little pressure on an upper floor, roughly 0.1 bar per metre of height between the tank and the tap.
- Buy a low-pressure tap if you are on gravity.Taps state a minimum working pressure. A designer tap rated at one bar minimum, fitted to a first-floor basin fed by a loft tank, will dribble. Look for taps specifically stated as suitable for low pressure or gravity systems, which have larger internal waterways.
- Check the tails.Taps come with rigid copper tails, with threaded tails for a tap connector, or with flexible braided tails already attached. Flexible tails make fitting in the space behind a basin dramatically easier and are worth choosing on that basis alone. Check they are long enough to reach your isolating valves.
- Check the fixing arrangement.A monobloc is usually held by a threaded rod and a horseshoe washer or a top-hat plate, which is fiddly but manageable. Pillar taps have a backnut on each tail. Either way, look at how much room there is under your basin before you buy something with an unusual fixing.
- Fit isolating valves while you have access.Small screwdriver-slot valves on each tail turn every future tap or waste job from a whole-house isolation into a five-minute one. If there are none, fit them at the same time as the tap.
- Consider the spout height and reach.A tall spout looks good and splashes badly in a small shallow basin. A short spout in a deep countertop bowl leaves you washing your hands against the back of the basin. Match the spout to the bowl, not to the photograph.
- Think about who uses it.A single-lever monobloc is far easier for someone with arthritic hands or limited grip than a pair of crosshead pillar taps. This is a genuine accessibility difference and it costs nothing to choose well.
Common mistakes
- Buying a mains-pressure tap for a gravity-fed system — It will trickle. The tap's minimum working pressure is a real specification, not marketing, and a loft tank on a first floor produces very little.
- Buying a three-hole mixer for a one-hole basin — The holes are cast into the ceramic. The tap has to match the basin.
- Not fitting isolating valves while the basin is disconnected — The next repair, five minutes' work with valves, becomes a whole-house isolation without them.
Alternatives
- Wall-mounted basin tap: Nothing on the basin, everything cleans easily, and the pipework goes in the wall. Beautiful and completely impractical to change later without opening the wall.
- Waterfall or open-spout tap: Looks striking and generally needs decent pressure to look right at all. Check the minimum pressure rating carefully — many are mains-only.
- Thermostatic or safety basin mixer: Limits the maximum outlet temperature. Worth considering where children or vulnerable adults use the basin, and a genuine scald-risk reduction.