Bathroom storage units
Most UK bathrooms have roughly a third of a square metre of dead storage space that gets used for nothing. The 200mm gap behind the toilet cistern. The 400mm cube under the basin.
The triangular corner between the wall and the bath. The narrow strip between a doorframe and a radiator. Each of these spaces is too small or oddly shaped for the storage solutions buyers usually think of, so they get left empty.
The right storage unit for each of those dead spaces turns them into useful capacity. This page is about which type of storage fits which kind of dead space.
What is a bathroom storage unit?
A bathroom storage unit is a standalone or semi-fitted piece designed specifically to add storage capacity to a bathroom, separate from the vanity (which combines basin and storage) and the bathroom cabinet (which is general-purpose closed storage). Storage units are usually purpose-built for a specific spatial problem: fitting under a basin, concealing the back of a toilet, sitting in a corner, or filling a narrow wall.
The defining feature is that the unit solves a space the vanity and the standard cabinet can’t. A wall-hung storage unit fits where a freestanding cabinet would crowd the floor. An under-sink unit fits the awkward shape around basin plumbing. A back-to-wall unit conceals cistern plumbing while adding usable surface. The unit is shape-matched to the problem; the standard cabinet rarely is.
Storage by space
Four kinds of dead space in UK bathrooms, with the storage that solves each:
- Under the basin (under-sink units). A pedestal basin leaves an open, awkward space underneath that collects nothing useful. An under-sink storage unit wraps around the pedestal (or sits beneath a wall-hung basin), turning that volume into closed storage for cleaning supplies and spare toiletries. Widths typically match the basin width: 500–700mm.
- Behind the toilet (back-to-wall units). A standard close-coupled toilet cistern projects forward into the room with empty wall space behind it. A back-to-wall WC unit conceals the cistern inside a flat-fronted cabinet and adds a worktop above plus hidden storage. The same footprint as the original cistern; meaningfully more useful.
- Corner (triangular corner units). The angle between two walls is one of the most-wasted spaces in a bathroom. Triangular corner storage units fit the angle precisely, adding capacity that a rectangular cabinet would refuse. Widths 400–600mm along each wall edge.
- Narrow alcoves and slim walls (slim storage units). The strip between a doorframe and a radiator, beside the toilet, or filling a 200–400mm wall gap that nothing standard fits. Slim storage units in widths from 200mm upward fit these gaps as if custom-built.
Storage for small bathrooms
Small bathrooms benefit most from the dead-space approach, because they have the least room to spare for traditional storage. Three principles for fitting genuine storage into a small bathroom:
- Go wall-hung where you can. Storage that clears the floor underneath makes the bathroom feel meaningfully more open. The visual difference is dramatic in rooms under 4m², and the cleaning is easier.
- Match the storage to the gap, not to a category. Don’t buy a "bathroom cabinet" because it’s the standard answer; buy a slim storage unit if a slim gap is what you actually have. Sizing to the room beats sizing to the category every time.
- Stack vertically. A tall storage unit in a 400mm-wide gap gives you the storage of three floor cabinets in the floor footprint of one. For small bathrooms, vertical capacity earns its place against horizontal capacity.
For the full small-bathroom approach, browse bathroom furniture by room size or tall bathroom units for the vertical-storage option.
Bathroom storage FAQs
What’s the best bathroom storage for a small space?
Slim wall-hung storage units in widths from 200mm fit gaps standard cabinets can’t. Under-sink units use the dead space around basin plumbing. Corner storage units fit the angle between two walls that rectangular cabinets refuse. Match the storage to the specific gap rather than buying a standard cabinet that fits approximately.
What is back-to-wall storage?
A back-to-wall WC unit conceals the toilet cistern and pipework inside a flat-fronted cabinet, with a worktop above and usually hidden storage in the cabinet body. Same wall footprint as a standard close-coupled toilet; meaningfully more useful because it adds storage and a usable surface where the original wall had neither.
Can I fit storage units myself?
Most freestanding storage units (under-sink, corner, slim freestanding) need only basic assembly and levelling. Wall-hung storage units are more involved because they need accurate marking and the right fixings for the wall type. Back-to-wall WC units almost always need a plumber, because the toilet plumbing needs to be reconfigured.
What size storage unit fits under a basin?
Match the basin width. A 600mm pedestal basin wants a 600mm under-sink unit; a 500mm basin wants a 500mm unit. The unit will have a cut-out shape that accommodates the pedestal or the plumbing. Worth checking the unit listing specifies basin compatibility, since not all under-sink units fit all basin shapes.
Do bathroom storage units need to match the vanity?
Ideally yes, especially if they’ll be visible together. Matching the finish (matt white storage with matt white vanity, oak storage with oak vanity) reads as a coordinated bathroom. If the storage is in a different part of the room and won’t be seen alongside the vanity, the matching matters less.
Filter the grid above by space type, width and mounting. For the broader storage range, browse bathroom cabinets or tall bathroom units.
Plumbworld has supplied UK bathroom storage since 1999, with a 4.8/5 rating from over 60,000 Trustpilot reviews, free UK delivery, a price match promise, and 365-day returns. Turning dead space into useful storage is a low-risk fix to commit to.
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