If you’ve searched for a tap installation tool b&q stocks, you’re almost certainly staring at a new tap, an old tap you can’t shift, and about six inches of pitch-black space behind the sink where your hand won’t fit. That cramped, awkward gap is the whole reason a dedicated tap tool exists. Below I’ll tell you exactly which tools do the job, which ones are marketing, what to buy, and how to actually use them — with real sizes, prices, and the mistakes that cost people a flooded cupboard.
Quick note on words: in the UK we say “tap”; in the US the same fitting is a “faucet.” They install the same way, so everything here applies whether your box says tap or faucet.
What Is a Tap Installation Tool, and Why Can’t I Just Use a Normal Spanner?
A tap installation tool is a specialist wrench shaped to reach and turn the fixing nuts hidden underneath and behind a sink — places a standard spanner physically cannot reach. You can’t just use a normal spanner because the backnut that clamps the tap to the sink sits flat against the underside of the basin, often 300–400mm back, with tails and supply pipes crowding it. A straight spanner has nowhere to sit and no room to swing.
There are three tools that solve this, and they overlap:
- Basin wrench (adjustable): a long shaft with a spring-loaded pivoting jaw at the end. You slide it up into the gap, the jaw grips the nut, and you turn from below where there’s room for your hand. Best all-rounder.
- Crows-foot / box tap spanner: a telescopic tube with shaped sockets on each end (usually a 4-way head) sized to the standard 3/4″ and 1/2″ backnuts. Cheap, brilliant for tight compression backnuts, but only fits specific nut sizes.
- Tap reseating & aerator keys: smaller add-ons for servicing rather than fitting — worth knowing they exist, not essential for a straight swap.
For a first-timer fitting a mixer tap, a basin wrench is the single most useful buy. If your tap uses standard plastic backnuts (most modern taps do), a telescopic tap spanner is even faster and grips the nut squarely so it won’t slip and crack the plastic.
What’s the Cheapest Set of Tools I Need to Fit a Kitchen Mixer Tap Under £30?
Under £30 you can buy everything needed to fit a standard kitchen or bathroom mixer tap: a telescopic tap spanner or basin wrench, PTFE tape, an adjustable spanner, and a small bucket or tray. That’s the entire kit — you do not need a full plumbing toolbox for one tap.
Here’s the honest shopping list, with typical B&Q / UK DIY-store price ranges in 2026:
| Tool | What it does | Typical price | Essential? |
|---|---|---|---|
| Telescopic tap spanner (crows-foot) | Turns 1/2″ & 3/4″ backnuts in the tight gap behind the sink | £8–£15 | Yes (or a basin wrench) |
| Adjustable basin wrench | Grips any nut size on a long reach; more versatile | £12–£20 | Yes (or a tap spanner) |
| PTFE tape (plumber’s tape) | Seals threaded joints on tap tails and connectors | £1–£3 | Yes |
| Adjustable spanner (150–200mm) | Tightens flexi-hose connectors and isolation valves | £6–£12 | Yes |
| Flexible tap connectors / flexis | Link tap tails to your supply pipes (often not included with tap) | £4–£8 each | Usually |
| Bucket / drip tray + old towel | Catches residual water when you disconnect the old tap | £0–£5 | Yes |
If I had to pick just one tool to add to a drawer that already has an adjustable spanner and PTFE, it would be the telescopic tap spanner. It’s the cheapest, it fits the exact nuts on modern monobloc taps, and its 4-way head means you rarely meet a backnut it can’t turn.
Do I Need Flexible Connectors, and Are They Included With the Tap?
Most modern monobloc mixer taps come with the flexible tap connectors (flexis) already attached to the tap tails — but not always, and the ones supplied are sometimes short. Check your box before you start. If your isolation valves are more than about 300mm from the tap, or your existing pipework uses 15mm compression, buy a pair of longer flexi connectors so you’re not stretching or kinking them. Kinked flexis restrict flow and are a leading cause of weak pressure on a brand-new tap.
How Do I Actually Use a Basin Wrench to Remove a Stuck Old Tap?
To use a basin wrench: turn off the water at the isolation valves, get under the sink on your back, slide the wrench up so its jaw wraps the backnut, and turn anticlockwise (viewed from below) to loosen. The pivoting jaw self-tightens as you push, so light steady pressure beats brute force.
Step by step, this is the reliable sequence I use every time:
- Isolate the water. Turn the slotted isolation valves on both supply pipes a quarter turn so the slot sits across the pipe (closed). No isolation valves? Turn off at the mains stopcock and open the tap to drain pressure.
- Open the old tap to release trapped water and confirm the supply is actually off.
- Disconnect the flexis or supply pipes with your adjustable spanner. Have the bucket underneath — there’s always a cupful of water left in the pipe.
- Attack the backnut. Fit the basin wrench jaw around the nut and turn to loosen. If it’s seized with limescale (very common in hard-water areas), spray penetrating oil, wait ten minutes, and try again. Don’t strip it.
- Lift the old tap out from above once the backnut is off.
- Clean the sink hole and surface — old sealant and grit stop the new tap seating flat.
The single most common wall people hit here is a backnut welded solid by years of limescale. If your area has hard water, that same buildup is quietly wrecking the inside of your fittings too — it’s worth reading how to clean a faucet head with CLR to shift hard-water buildup so your new tap doesn’t seize the same way in five years.
Basin Wrench vs Telescopic Tap Spanner — Which Should I Buy?
Buy the telescopic tap spanner if your tap uses standard-sized plastic or brass backnuts (most monobloc taps) and you want the cheapest, squarest grip; buy the adjustable basin wrench if you’re dealing with odd nut sizes, older imperial fittings, or you want one tool that copes with future jobs too. Many people who do more than one tap end up owning both.
| Factor | Telescopic tap spanner | Adjustable basin wrench |
|---|---|---|
| Best for | Standard 1/2″ & 3/4″ backnuts on modern taps | Any nut size, awkward or worn nuts |
| Grip | Full square socket — won’t slip or round the nut | Two-point jaw — can slip on very tight nuts |
| Reach | Telescopes, but fixed head angle | Long shaft, pivoting head reaches deeper |
| Price | £8–£15 | £12–£20 |
| Learning curve | Very easy | Slight — jaw direction takes a moment to learn |
My plain-English recommendation: if you’re fitting one standard kitchen or bathroom mixer, get the telescopic tap spanner. If your house is older, has imperial or unusual pipework, or you know you’ll be doing bathroom jobs over the next few years, spend the extra fiver on the basin wrench.
How Do I Fit the New Tap Once the Old One Is Out?
Fitting the new tap reverses the removal: drop the tap through the sink hole on its rubber gasket, tighten the backnut up from below with your tap tool, connect the flexis to the isolation valves, then slowly turn the water back on and check for leaks. The whole fit takes 15–30 minutes once the old tap is gone.
The details that actually matter:
- Seat it on the supplied gasket/washer — the rubber or foam seal sits between tap base and sink. Don’t reuse a squashed old one.
- Hand-tighten the backnut first, line the spout up straight, then nip it up with the tap tool. Snug, not gorilla-tight — overtightening cracks ceramic basins and plastic nuts.
- Wrap PTFE tape clockwise around any threaded joint that isn’t a rubber-sealed flexi connector — 4 to 6 wraps.
- Connect hot to hot, cold to cold. On a monobloc, the tails are usually marked blue and red.
- Turn the water on slowly and watch every joint for 60 seconds. A weep now is easy; a drip you didn’t check is a wet cupboard tomorrow.
If you’re swapping a bathroom basin tap specifically, the isolation-valve approach and no-plumber method are the same ones I walk through for a bidet faucet replacement without calling a plumber. And if your new tap is a wall-fed or two-hole design rather than a single monobloc, the fixings differ — this guide to a wall mount faucet two-hole setup covers what changes.
What Goes Wrong — and How Do I Avoid a Leaking New Tap?
Most new-tap leaks come from three things: an over- or under-tightened backnut, a crossed thread on a flexi connector, or a torn rubber washer — not from a faulty tap. Fix the fitting, not the tap.
Run through this if you spot a drip after turning the water back on:
- Weeping at the flexi connector nut? It’s usually cross-threaded or not quite tight. Undo it, check the thread starts cleanly by hand, re-tighten firmly but not brutally.
- Water pooling under the tap base? The backnut is loose or the base gasket is misaligned. Re-seat and re-tighten from below.
- Slow drip from the spout after use? That’s a cartridge or aerator issue, not installation — often a worn washer. Here’s why the small parts matter: the humble faucet aerator washer is a frequent, cheap culprit.
- No pressure? Check your flexis aren’t kinked and both isolation valves are fully open.
One rule that saves grief: don’t remove the aerator or run the new tap at full blast for the first minute. Old pipework loosens grit when you disturb it, and that grit blocks the new aerator. Run cold, then hot, gently for 30 seconds to flush the line before you judge the flow.
Do I Ever Actually Need a Plumber for This?
You need a plumber only in three situations: there are no isolation valves and you’re not confident touching the mains, the pipework is soldered copper with no easy disconnect, or you find corroded/leaking supply pipes when you get under there. A straightforward like-for-like tap swap on modern pipework is a genuine DIY job.
Be honest with yourself about the pipework. If the space is so tight you can’t get your hand plus a tool in, if the pipes are lead (older properties), or if turning a valve reveals it’s seized and weeping, stop and call someone. A £150 plumber call-out is cheaper than a ruined kitchen unit. Everything short of that, the tools above handle.
FAQ
Does B&Q sell a specific “tap installation tool,” or do I ask for something else?
Ask for a “basin wrench,” “tap spanner,” or “crows-foot tap spanner” — that’s the tap installation tool people mean. B&Q and most UK DIY stores stock all three in the plumbing aisle, typically £8–£20. There isn’t one single branded “tap tool”; it’s the category of long-reach wrenches designed for backnuts.
Can I fit a tap with just an adjustable spanner and no special tool?
Sometimes, on a very open under-sink space, yes — but usually no. The backnut sits too far back and flat against the basin for an adjustable spanner to grip and swing. That’s precisely the gap a basin wrench or telescopic tap spanner is built for, and skipping it is why most first-timers give up halfway.
How long does it take to change a tap yourself?
Budget 45–90 minutes for your first tap, most of which is fighting the old backnut and cleaning up. Once the old tap is out, fitting the new one is genuinely 15–30 minutes. Hard-water seizing and awkward access are the only things that blow the timing out.
What size are the nuts a tap spanner needs to fit?
Standard UK monobloc taps use 1/2″ and 3/4″ backnuts, which is why 4-way telescopic tap spanners carry exactly those sockets. Older or imperial fittings can vary, which is when an adjustable basin wrench earns its place — it grips any size rather than relying on a fixed socket.
Do I need PTFE tape on a modern tap with rubber-sealed flexi connectors?
No — flexi connectors with a rubber washer seal on compression and must not be taped, as PTFE can stop the washer seating. Use PTFE only on threaded metal-to-metal joints, such as connecting a flexi’s female thread onto an isolation-valve tail where there’s no rubber seal.
Is it worth buying the tool, or hiring one?
Buy it. A telescopic tap spanner costs about the same as an hour’s tool hire plus the deposit and travel, and you’ll keep it for the next tap, the outdoor stopcock, and every future bathroom job. It lives in a drawer and pays for itself the first time you don’t call a plumber.
Author Note & Why You Can Trust This Guide
This guide was written by the fixtures team at Adeaga, a specialist retailer of kitchen and bathroom taps, showers and fittings. We fit, test and photograph the taps we sell, and we handle the warranty claims when things go wrong — so our advice is shaped by what actually fails in real homes, not just spec sheets. Every fitting method here follows UK water regulations (WRAS) and standard manufacturer installation guidance; taps we stock are pressure-tested and carry manufacturer warranties (commonly 5 years on the body and cartridge). When in doubt about your own pipework, follow your tap manufacturer’s supplied instructions and local water byelaws.
Do the job once, with the right £10 tool, and you’ll wonder why you ever thought it needed a plumber.