A toilet is a sanitary fixture in the bathroom used for the evacuation of wastewater, and it is primarily classified by its installation type (floor-mounted, wall-hung, or back-to-wall), by the orientation of its waste outlet (vertical, horizontal, or dual), and by its flushing system. Getting these three parameters right ensures it fits your bathroom.
Changing a toilet seems simple until you discover that the new one doesn't match your waste outlet or that it protrudes too much in a small bathroom. Choosing correctly depends on understanding three interconnected decisions—type, outlet, and measurements—before focusing on design. In this guide, we review them one by one with real data from models in the Merkimarket toilet catalog, so you can make an informed purchase without surprises on installation day.
Key data before choosing a toilet
- Types by installation: floor-mounted (the most common), wall-hung (attached to a frame, with the floor clear), and back-to-wall (conceals the visible cistern without requiring construction work).
- Outlet types: vertical (to the floor), horizontal (to the wall), and dual, which accommodates both orientations.
- Critical measurement: the distance from the waste outlet to the wall or floor determines which models are compatible; measure it before buying.
- Flush: dual-flush systems (usually 3/4.5 or 3/6 liters) allow you to save water with each use.
- Rimless technology: a pan without an internal rim, more hygienic and easier to clean, present today in most ranges.
- Formats: compact versions exist (around 36.5 cm usable depth) for small bathrooms and comfort height or adapted height for reduced mobility.
- Material: sanitary porcelain for the pan; the seat can be made of Supralit-type resin or other thermoplastics, with or without soft-close.
With this map, you can orient yourself; below, we develop each point so that the decision is yours and not left to chance.
Types of toilets by installation
The first major fork in the road is how the toilet is supported, because this affects construction, aesthetics, and cleaning.
Floor-mounted toilet with cistern. This is the classic close-coupled model: the pan rests on the floor, and the cistern is attached above it. It is the easiest option to install and replace, the most economical, and offers the most spare parts. Models like the Roca Victoria with vertical outlet are a typical example of this format.
Wall-hung toilet. The pan 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 requires installing a frame and a concealed cistern, meaning more construction work. If this option appeals to you, it's advisable to read the advantages and disadvantages in our guide to wall-hung toilets first.
Back-to-wall. It rests on the floor but is completely flush with the wall, thus concealing the outlet and providing a clean look without the need for 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 errors in online purchases. The outlet is where the toilet discharges to the waste pipe, and it must match the installation you already have at home.
The vertical outlet (or "to floor") discharges downwards and is common in homes where the soil pipe is under the floor slab. The horizontal outlet (or "to wall") discharges backward and is the most widespread in new construction and modern renovations. The dual outlet is the most versatile: it is prepared to connect 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 soil pipe under the floor 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 are unsure about your outlet | The Gap Square dual outlet |
If your waste pipe exits through the wall, you need a horizontal outlet model; if it exits through the floor, a vertical one. When in doubt, the dual option covers you.
Measurements: how to measure your bathroom before buying
A toilet that doesn't fit or leaves the door scraping is an expensive problem to correct. Before choosing, follow these steps:
- Measure the outlet. If it's horizontal, note the distance from the center of the waste pipe to the finished floor; if it's vertical, the distance from the center of the waste pipe to the back wall. This is the most important compatibility data.
- Check the available depth. Measure from the wall to where the pan can protrude. In small bathrooms, compact formats (around 36.5 cm deep) gain crucial space.
- Allow for usage clearance. Reserve about 20 cm on each side of the toilet's axis and sufficient front space to sit comfortably.
- Consider the height. Comfort height or adapted versions facilitate use for elderly people or those with reduced mobility, an increasingly common factor in renovations.
To further refine your bathroom layout, you'll find our toilet buying guide by materials, height, and flush useful.
Flushing systems and water saving
The flushing mechanism affects both comfort and your bill. Modern toilets use dual-flush cisterns, which offer a full flush and a reduced flush—common values of 3/4.5 or 3/6 liters—to avoid excessive water usage with each flush. Compared to old single-button, large-volume cisterns, the annual water saving in a home is considerable.
In addition, there's rimless technology, which eliminates the internal rim of the pan where water traditionally circulated. Since there is no such cavity, less dirt accumulates, cleaning is faster, and water distribution during flushing is more efficient. Today, you'll find it in almost all ranges, from wall-hung models to close-coupled ones.
Materials, seat, and finishes
The pan and cistern are made of sanitary porcelain, a vitrified material that is resistant, hygienic, and easy to clean, making it the industry standard. Where there are noticeable differences is in the seat: there are conventional thermoplastic seats and high-density resin seats like Supralit, which are more rigid and stable, and many include a soft-close system that prevents slams and noise. Some models also allow for quick seat removal for thorough cleaning of the hinge area.
In terms of style, white porcelain remains the majority, but rounded designs—like the The Gap Round family—coexist with more squared and contemporary lines, and even classic-inspired proposals like the Roca Dama Retro. Choose the shape considering the overall bathroom design and ease of cleaning: 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 seek simplicity and price; wall-hung or back-to-wall if you prioritize aesthetics and cleanliness and accept more construction work.
- Adjust to your measurements. Compact for small bathrooms, comfort height if there are elderly people at home.
- Finalize features. Rimless for hygiene, dual flush for water saving, and soft-close seat for everyday use.
With these four decisions made, choosing the specific model is almost automatic. You can see them all in the Merkimarket toilet catalog, with shipping throughout 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 waste pipe: if the pipe goes down into the floor, it's a vertical outlet; if it enters the back wall, it's horizontal. If you are renovating and are unsure, a dual outlet model accommodates both orientations.
What is the difference between a rimless and a conventional toilet?
A rimless toilet has no internal rim in the pan, so it accumulates less dirt, is quicker to clean, and distributes flushing water more effectively. A conventional toilet retains the 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 toilets, which leave the floor clear and create a sense of spaciousness.
How much water does a modern toilet use?
Current dual-flush cisterns typically offer flushes of 3/4.5 or 3/6 liters, significantly less than older single-flush cisterns, which notably reduces annual consumption.
Article written by the Merkimarket editorial team. Technical data (outlet types, formats, flush, and materials) taken from the actual product sheets in the Merkimarket toilet catalog. Measurements and availability may vary by model; consult each product sheet for current information in Spain.
