Under Counter Basins

An under counter basin, sometimes called an undermount basin, sits beneath the worktop and leaves the surface around the bowl clear. These FAQs cover replacing an existing basin, choosing a suitable worktop, checking the space below and understanding what installation and cleaning involve.

 

Can I replace an existing under counter basin without changing the vanity?

You may be able to keep the existing vanity unit and worktop if they remain strong and undamaged.

Measure the exact size and shape of the existing opening, then check how the new basin will align with the cut edge. It must provide enough overlap beneath the worktop for its specified mounting method. Do not assume that two basins with similar overall dimensions will fit the same opening.

Check the space below for the bowl, waste, pipework, drawers and cabinet supports. You should also inspect the worktop for cracks, water damage or weakened fixing points around the opening. The existing brackets or rails may not suit the new basin, so follow its fitting instructions rather than reusing them automatically.

 

Will an under counter basin work with a quartz or stone worktop?

Yes, as long as the worktop is suitable for an under counter basin. Quartz, granite and other solid surfaces commonly work with under counter basins because their exposed cut edges can be shaped and finished. A specialist will usually need to cut and polish these materials accurately and confirm how the basin should be supported. Some natural stone surfaces may also need sealing and suitable ongoing care.

Standard laminate worktops are not normally suitable unless the manufacturer specifically approves them for under counter installation, as cutting the opening can expose a moisture-sensitive core that may swell or deteriorate if water reaches it.

 

How deep should an under counter basin be?

There's no one right depth, so look at the bowl itself as well as the overall size of the basin. A deeper bowl gives you more room when washing your hands or face and can also help keep splashes inside the basin. If you're looking to buy a large undermount bathroom sink, make sure there's enough room underneath the worktop for the bowl and plumbing too.

 

Are under counter basins easy to install?

Installing an under counter basin requires accurate cutting, alignment and support. Use the manufacturer's dimensions or cutting template rather than calculating the opening from the basin's overall size.

The basin must attach securely beneath the worktop using the specified brackets, rails, clips or supporting frame. Do not rely on sealant alone to carry its weight; sealant is needed instead for the joint between the basin and worktop in order to stop water getting between the two surfaces.

 

Are under counter basins easy to clean?

The lack of a raised rim on top of the worktop makes it easier to wipe water and residue from the surrounding surface towards the bowl. It also creates a clear, uninterrupted area around the basin.

Clean the joint between the basin and worktop regularly, as residue can collect along the edge. Follow the care instructions for both materials and avoid leaving water around an exposed worktop edge, particularly if the surface requires sealing.