How to Fix Cracked Sink

A cracked sink is rarely a reason to panic, but it does need attention promptly. A hairline crack in a ceramic basin that is dry and stable can often be repaired with a £20 kit from a builders’ merchant in under an hour. A crack that is weeping, spreading, or in a structural position is a different matter, continued use risks water damage to the cabinet below, and in some cases the basin may shatter.

The repair route depends on two things: the material the sink is made from, and the severity of the crack. This guide covers ceramic, composite, and acrylic sinks, the three most common domestic types in UK bathrooms and kitchens.

Diagnosing the Crack

Before reaching for a repair kit, assess what you are dealing with.

Hairline crack: a fine surface crack, often caused by thermal shock (pouring boiling water into a cold ceramic, or vice versa). The crack does not penetrate through the full thickness of the material and the basin holds water normally. Low urgency; cosmetic repair is sufficient.

Through crack: a crack that runs through the full thickness of the sink wall. Water may seep through when the basin is filled. This is a structural issue. The sink will likely worsen over time.

Chip at the rim or drain: not a crack per se, but a piece of material has broken away. Repair kits work well here, though a chip on the drain rim can expose metal and cause rust staining on vitreous enamel sinks.

Spiderweb cracking (crazing): a network of fine cracks across the glaze of a ceramic sink. This is cosmetic degradation of the glaze rather than a structural failure. It cannot be fully repaired without resurfacing.

Dry the sink completely and examine in good light. Run a fingernail across the crack, if it catches, the crack has depth. If water sits in the crack, it is through the glaze at minimum.

Repair Options at a Glance

How to Repair a Cracked Ceramic or Vitreous Enamel Sink

Ceramic basins (fired clay with a glaze) and vitreous enamel (steel or cast iron with a baked-on glaze) respond well to the same repair approach for hairline or surface cracks.¹

What you need

• Porcelain or enamel repair kit (available from Screwfix, Toolstation and plumbers’ merchants; Cramer is one widely stocked brand)
• Fine-grit sandpaper (400–600 grit)
• Acetone or isopropyl alcohol
• Small artist’s brush or the applicator provided in the kit
• Masking tape

Branded kits sit at the top of the price range: Toolstation listed the Cramer Kitchen & Bath Repair Kit, for porcelain, enamelled steel, cast iron and acrylic, at £38.99 in September 2026.¹

Step-by-step

1. Dry thoroughly. Turn off the water supply and leave the basin unused for at least two hours. Use a hairdryer on a low setting to ensure the crack is completely dry, moisture prevents adhesion.

2. Clean the area. Wipe around the crack with acetone or isopropyl alcohol on a clean cloth. Remove any soap scum, limescale, or grease.

3. Lightly abrade. For chips and larger surface cracks, lightly sand the repair area with 400-grit paper to give the filler a key. For fine hairline cracks, skip this step.

4. Mix the filler. Most two-part kits involve mixing a resin and a hardener. Follow the manufacturer’s ratio exactly, incorrect mixing prevents proper cure.

5. Apply in thin layers. Work the filler into the crack using the applicator brush. For deeper repairs, build up in thin coats (1mm at a time), allowing each to partially cure per the manufacturer’s instructions before adding the next.

6. Sand flush. Once fully cured (usually 24 hours), sand the repair flush with 600-grit paper, working carefully so as not to scratch surrounding glaze.

7. Paint or glaze over. Most repair kits include a touch-up paint. Apply in thin coats. For white sinks, a paint pen in bright white (such as those sold specifically for porcelain) gives a cleaner finish than brush application.

The result on a hairline crack is virtually invisible. On a chip, there may be a slight texture difference, but colour and function are fully restored.

How to Repair a Cracked Composite Sink

Composite kitchen sinks (typically made from quartz, granite, or acrylic bound in resin, brands include Blanco, Franke, and Schock) are harder to repair invisibly because they have a through-colour and textured surface rather than a separate glaze.

For hairline cracks, a two-part clear epoxy adhesive (such as Araldite Rapid) can be worked into the crack to stabilise it. Once cured, lightly sand and buff with a composite cleaner. The crack will often still be visible but structurally sound.

For deeper cracks, specialist composite repair kits are available that include coloured fillers matched to common sink colours. Application is similar to the ceramic method above. A perfect colour match is difficult without the manufacturer’s own repair compound.

For through cracks in a composite sink, professional repair by a kitchen sink specialist is worth considering before replacement. A skilled repairer can often achieve a structurally sound and near-invisible result. Expect to pay £100–£250 for a professional visit.

How to Repair a Cracked Acrylic Sink

Acrylic (plastic) basins, found in some low-cost bathroom suites, are the easiest to repair at home. Acrylic is flexible and can be chemically bonded.

1. Clean and dry the area as above.
2. Apply a thin bead of acrylic adhesive or a two-part epoxy rated for plastics into the crack.
3. Clamp or tape the crack closed while the adhesive cures.
4. Once cured, sand smooth and apply an acrylic touch-up spray or paint.

Acrylic is also relatively cheap to replace if the crack is severe. A new acrylic bathroom basin can be bought from a plumbers’ merchant for £40–£120, and a plumber will fit it in under an hour.

When to Call a Professional

• Any crack that is weeping or spreading during normal use
• Cracks in the base of the bowl rather than the rim (higher structural stress)
• Ceramic or vitreous enamel cracks wider than 2mm (filler may not bond reliably)
• Any crack on a Belfast or butler sink supported by a false floor cabinet (movement in the cabinet can worsen cracks over time)
• Where the repair needs to be invisible for aesthetic reasons (estate agents, rental properties, listed interiors)

Plumbers can advise on whether repair or replacement is more economical. A plumber’s day rate in 2026 is typically about £270–£350 outside London, and more in London.²

Replacement Sink Costs in 2026

If repair is not viable, a replacement is often more cost-effective than a professional repair for cheaper basins. The figures below are for one basin, supplied and fitted.

For comparison, Toolstation listed an Armitage Shanks Sandringham 21 45 cm basin at £101.99 in September 2026.³

Always turn off the water before attempting any repair or disconnection, and ensure you know the location of your stopcock before starting work.