A toilet is the sanitary fixture in the bathroom intended for the disposal of fecal waste, and it is primarily classified by its installation type (floor-mounted, wall-hung, or back-to-wall), by the orientation of its drain outlet (vertical, horizontal, or dual), and by its flushing system. Getting those three parameters right is what ensures it will fit in your bathroom.
Changing a toilet seems simple until you discover that the new one doesn't match your drain outlet or that it protrudes too much in a small bathroom. Choosing correctly depends on understanding three sequential decisions—type, outlet, and dimensions—before looking at the design. In this guide, we review them one by one with actual data from models in the Merkimarket toilet catalog, so you can buy with sound judgment and avoid surprises on installation day.
Key data before choosing a toilet
- Installation types: floor-mounted (the most common), wall-hung (fixed to a frame, with clear floor space), and back-to-wall (conceals the exposed cistern without construction work).
- Outlet types: vertical (to the floor), horizontal (to the wall), and dual, which supports both orientations.
- Critical dimension: the distance from the drain to the wall or floor determines which models are compatible; measure it before purchasing.
- Flush: dual-flush systems (typically 3/4.5 or 3/6 liters) allow for water savings with every use.
- Rimless technology: a bowl without an inner rim, which is more hygienic and easier to clean, now present in most product ranges.
- Formats: there are compact versions (around 36.5 cm of useful depth) for small bathrooms and comfort height or adapted versions for reduced mobility.
- Material: sanitary porcelain for the bowl; the seat can be Supralit-type resin or other thermoplastics, with or without soft-close dampers.
With this map, you can now orient yourself; below, we develop each point so that the decision is yours and not left to chance.
Types of toilets based on installation
The first major fork in the road is how the toilet is attached, because construction, aesthetics, and cleaning depend on it.
Floor-mounted toilet with cistern. This is the classic close-coupled model: the bowl rests on the floor and the cistern is coupled on top. It is the easiest option to install and replace, the most economical, and the one that offers the most spare parts. Models like the Roca Victoria with vertical outlet are the typical example of this format.
Wall-hung toilet. The bowl is fixed to a frame embedded in the wall and remains "floating," with the floor clear beneath it. It gains in aesthetics and facilitates cleaning, but it requires installing a frame and a concealed cistern, meaning more construction work. If you are drawn to this option, it is worth reading the advantages and disadvantages in our guide on wall-hung toilets first.
Back-to-wall. It rests on the floor but is completely flush against the wall, hiding the outlet so the set looks clean without needing a frame. Models like the Roca The Gap Round back-to-wall comfort height are a good representative of this family.
Toilet outlets: vertical, horizontal, and dual
This is the point that causes the most mistakes in online shopping. The outlet is where the toilet discharges into the drain, and it must match the plumbing you already have at home.
The vertical outlet (or "floor outlet") discharges downward and is common in homes where the waste pipe is under the floor slab. The horizontal outlet (or "wall outlet") discharges backward and is the most widespread in new construction and modern renovations. The dual outlet is the most versatile: it comes prepared to be connected vertically or horizontally as needed, which reduces the risk of buying the wrong model.
| Outlet type | Where it discharges | Where it is common | Catalog example |
|---|---|---|---|
| Vertical | To the floor | Homes with waste pipe under the slab | Roca Victoria vertical outlet |
| Horizontal | To the wall | New construction and recent renovations | Roca Victoria close-coupled horizontal |
| Dual | Vertical or horizontal | When you aren't sure about your outlet | The Gap Square dual outlet |
If your drain exits through the wall, you need a horizontal outlet model; if it exits through the floor, a vertical one. In case of doubt, the dual covers your back.
Dimensions: how to measure your bathroom before buying
A toilet that doesn't fit or leaves the door grazing is an expensive problem to fix. Before choosing, follow these steps:
- Measure the outlet. If it is horizontal, note the distance from the center of the drain to the finished floor; if vertical, the distance from the center of the drain to the back wall. This is the most important compatibility data point.
- Check the available depth. Measure from the wall to where the bowl might protrude. In small bathrooms, compact formats (around 36.5 cm deep) save decisive space.
- Leave clearance for use. Reserve about 20 cm on each side of the toilet centerline and sufficient front space to sit comfortably.
- Think about the height. Comfort height or adapted versions facilitate use for the elderly or those with reduced mobility, a factor that is increasingly common in renovations.
To further refine your bathroom layout, our buying guide for toilets by material, height, and flush will be useful.
Flushing systems and water saving
The flush mechanism influences both comfort and your utility bill. Current toilets use dual-flush cisterns, which offer a full flush and a reduced one—standard values of 3/4.5 or 3/6 liters—so you don't waste more than necessary per use. Compared to old, high-volume single-button cisterns, the annual water savings in a home are considerable.
Added to this is rimless technology, which eliminates the inner rim of the bowl where water traditionally circulated. Since there is no gap, less dirt accumulates, cleaning is faster, and water distribution during the rinse is more efficient. Today, you will find it in practically all ranges, from wall-hung to close-coupled models.
Materials, seat, and finishes
The bowl and cistern are manufactured in sanitary porcelain, a vitrified, resistant, hygienic, and easy-to-clean material that is the industry standard. Where there are appreciable differences is in the seat: there are conventional thermoplastic ones and high-density resin types like Supralit, which are more rigid and stable, and many incorporate a soft-close system that prevents banging and noise. Some models also allow for quick removal of the seat to thoroughly clean the hinge area.
Regarding style, white porcelain remains the most common, but rounded designs coexist—such as the The Gap Round family—with more square and contemporary lines, and even classic-style proposals like the Roca Dama Retro. Choose the shape with the overall bathroom look and ease of cleaning in mind: the fewer nooks and crannies, the better.
How to choose your toilet in 4 steps
- Identify your outlet. Vertical, horizontal, or, if in doubt, opt for a dual model. This data takes precedence over design.
- Decide on the installation type. Floor-mounted if you are looking for simplicity and price; wall-hung or back-to-wall if you prioritize aesthetics and cleanliness and are willing to accept more construction work.
- Adjust to your dimensions. Compact for small bathrooms, comfort height if there are elderly people at home.
- Finalize features. Rimless for hygiene, dual-flush to save water, and a soft-close seat for daily comfort.
With those four decisions made, choosing the specific model is almost automatic. You can see them all in the Merkimarket toilet catalog, with shipping to all of Spain.
Frequently asked questions about toilets
How do I know if my toilet has a vertical or horizontal outlet?
Observe where it connects to the drain: if the pipe goes down into the floor, it is a vertical outlet; if it enters the rear wall, it is horizontal. If you are going to renovate and aren't sure, a dual-outlet model supports both orientations.
What is the difference between a rimless and a conventional toilet?
The rimless one has no inner rim in the bowl, so it accumulates less dirt, cleans faster, and distributes rinse water better. The conventional one keeps that traditional perimeter rim.
Which toilet is best for a small bathroom?
Compact models, with a reduced depth of around 36.5 cm, or wall-hung ones, which leave the floor clear and create a sense of spaciousness.
How much water does a modern toilet use?
Current dual-flush cisterns usually offer 3/4.5 or 3/6-liter flushes, well below old single-button cisterns, which significantly reduces annual consumption.
Article written by the Merkimarket editorial team. Technical data (outlet types, formats, flushing, and materials) taken from the actual specification sheets in the Merkimarket toilet catalog. Dimensions and availability may vary by model; consult each specification sheet for information valid in Spain.
