How to Cut Holes in Tiles for Pipes and Taps

Learning how to cut holes in tiles is the step that stops most bathroom and kitchen tiling jobs in their tracks. Nearly every wall has a pipe, a tap tail, a shower riser or a waste that has to pass through the tile, and a single cracked tile at that point can hold up a whole day. The good news is that the job is straightforward once you match the right tool to the size of hole and take the heat out of the cut. This guide covers every method a tiler in Bromley uses day to day, from a neat 8mm hole for a screw to a 65mm opening for a soil pipe.

Before you start, know that porcelain is the hardest common tile and the least forgiving. Natural stone and standard ceramic are softer and quicker to cut, but the same rules apply: keep the tile cool, let the tool do the work, and never push.

Which tool for which hole

There are three broad jobs, and each has its own kit.

Small holes (5mm to 12mm) for wall plugs, brackets and screws: a spear-point or diamond tile drill bit.
Medium to large round holes (25mm to 90mm) for pipes, taps, shower valves and wastes: a diamond hole saw (also called a core bit).
Openings and cut-outs that run in from the edge of a tile, such as a slot around a soil pipe or a rebate for a consumer unit: an angle grinder with a diamond blade, a tile jigsaw blade, or tile nibblers for a rough shape.

Cheap tungsten-tipped bits will cut ceramic but they overheat and skate on porcelain. Diamond-coated bits cut every material and last far longer, so they are worth the extra outlay if you have more than a couple of holes to make.

How to drill a small hole in a tile

Small holes are where beginners crack the most tiles, usually because the bit wanders across the glaze before it bites.

Mark the centre and stick a cross of masking tape over it. The tape gives the bit something to grip and stops it skating.
Set the drill to a low speed with the hammer action switched off. Hammer action shatters tiles.
Start at a shallow angle to score a small notch, then bring the drill upright and drill straight.
Keep the bit cool. A damp sponge held against the tile, or a squirt of water every few seconds, stops the tip burning out.
Ease off the pressure as you feel the bit break through the back of the tile, so you do not crack the reverse face or the plasterboard behind it.

How to cut a large hole with a diamond hole saw

A diamond hole saw cuts the clean round holes you need for pipes and taps. Work on a firm, flat surface such as a piece of scrap timber.

Measure the pipe and add a couple of millimetres of clearance so the tile is not tight against it. A 22mm pipe usually wants a 28mm to 32mm hole to allow for a pipe collar.
Use a guide. A cheap plastic drilling jig, or a piece of ply with a pilot hole of the same diameter clamped over the tile, holds the crown in place until it has scored a ring. Many hole saws have no centre pilot, so this step is what keeps the cut round.
Drill at a low speed and keep the crown wet throughout. Dry cutting overheats the diamonds and chips the glaze. A small dam of plumber’s putty around the mark holds a puddle of water over the cut.
Tilt the saw slightly to open a groove, then bring it flat and let the ring sink under its own weight. Light, steady contact cuts faster than force.
Slow right down for the last millimetre so the core drops out cleanly rather than blowing out the back.

Cutting a hole when the tile is already on the wall

Sometimes a pipe has to pass through a tile that is already fixed, for example when adding a towel rail or a new tap. You cannot flood a fixed tile with water, so keep a spray bottle to hand and mist the bit every few seconds. Drill slowly, take frequent breaks to let the crown cool, and expect the cut to take longer than on a loose tile. Protect the bath, basin or floor below with a towel, because the slurry that runs off is gritty and stains grout.

Cutting an opening from the edge of a tile

When a large waste or soil pipe sits near the edge of a tile, a full round hole is not always practical. Instead, cut a U-shaped notch so the tile slides in around the pipe.

Mark the shape, then cut the two straight sides with an angle grinder fitted with a diamond blade, or with a wet cutter for a cleaner finish.
Cut across the top of the U in a series of close relief cuts, then snap out the waste with tile nippers and tidy the curve.
A tile file or a diamond hand pad smooths the edge. It will be hidden by the pipe collar or an escutcheon plate, so it does not need to be perfect.

Common mistakes to avoid

Using hammer action. The single fastest way to crack a tile. Check it is off before every hole.
Drilling too fast. High speed builds heat, and heat kills diamond bits and chips glaze.
No water. Even a damp sponge makes the difference between a clean hole and a burnt, chipped one.
No clearance. A hole cut tight to the pipe leaves no room for movement and can crack when the pipe warms and expands.
Drilling near the edge. Keep holes at least 15mm from the tile edge where you can, as tiles split easily close to a corner.

Frequently asked questions

Can you cut a hole in a tile without a special drill bit?

Not reliably. An ordinary masonry or HSS bit will crack ceramic and simply polish porcelain without cutting. A diamond or spear-point tile bit is inexpensive and pays for itself on the first tile it saves.

Do you need water to cut porcelain tiles?

Yes. Porcelain is dense and builds heat quickly, so water cooling is essential to keep the diamond bit cutting and to stop the glaze chipping. On a tile that is already fixed, mist it with a spray bottle and pause often to let it cool.

What size hole should I cut for a pipe?

Cut two to four millimetres larger than the pipe or its collar. A 15mm pipe suits a roughly 20mm hole and a 22mm pipe a 28mm to 32mm hole. The gap lets the pipe move and is covered by a collar or escutcheon.

How do I stop the drill bit slipping on the tile?

Cover the mark with masking tape and start the drill at a shallow angle to score a notch, then bring it upright. The tape gives grip and the notch stops the tip wandering across the glaze.

Should I cut tiles before or after fixing them?

Cut before fixing wherever possible. Working on a loose tile lets you use a guide, apply water freely and support the tile fully, all of which reduce the risk of cracking. Only drill fixed tiles when a fitting has to be added later.

Holes in the wrong place, or a tile cracked on the last cut, are among the most common reasons a bathroom re-tile runs over. If you are dealing with dense porcelain, a run of tricky cut-outs or an expensive tile you cannot afford to waste, a professional finish is worth the call. You can see the rest of our tiling guides on the Bromley Tilers homepage, or read the standards set out by The Tile Association for how a job should be specified.

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