Today’s article answers the question of whether bidets can be installed on any toilet. It’s a great question and one that’s more complicated than you’d think. There are several types of bidets and even more types of toilets. So, unsurprisingly, some installations will be easier than others.
For specific recommendations, see the article on bidets that fit any toilets.
Can a Bidet Be Installed on Any Toilet?
Bidets can be installed on any toilet. With most toilets, installing the bidet is straightforward. However, some situations call for extra parts and, in rare cases, permanent alterations to the bathroom. Issues arise with certain toilet designs and when there’s no shutoff valve.
So, in theory, bidets can be installed on any toilet—at least, they’re designed to. In practice, it works out most of the time, but problems can arise that prevent an installation unless certain measures are taken. It will depend on the person whether it’s worth installing a bidet if drastic measures are needed.
Also, some bidets are meant to be more universal, while others are made to fit certain toilet designs (i.e., elongated vs. round). So not any bidet will fit just any old toilet. But as the old saying goes, “for every bidet there’s a toilet and for every toilet, there’s a bidet”.
For the TLDR version, have a look at this chart.
| Type of Toilet | Bidet Friendly? |
| Two-Piece | Yes |
| One-Piece | Usually |
| Flushometer | Usually Not |
| Wall-Hung (Concealed Cistern) | Usually Not |
| Skirted Design/ Concealed Trapway | Yes |
In case you’re new to the subject, here’s a rundown of the different types of bidets.
Most Bidets Can Be Installed on Two-Piece Toilets
With two-piece toilets, the tank and bowl are made separately and then attached such that the tank sits on/at the back of the basin.
Like all flush tank commodes, a two-piece toilet operates via gravity. (Sometimes the tank is used to house a pump that operates off of pressure but that’s a much less common design).
Flush tank toilets come in both one- and two-piece and the latter are much more bidet-friendly overall.
Two-piece toilets are the best but some may be incompatible with warm water non-electric bidets.
Advantages of Two-Piece Toilets for Bidets
Easy access to the Fill Valve for Installation
Having a tank, you can access the fill valve to easily install a bidet. The fill valve is a threaded shank that extends from the bottom of the tank that serves as an inlet for incoming water. Bidets come with a T-connector that attaches to this valve to divert some of the water to the bidet.
Traditional Dimensions
Toilet designs can be pretty modern and progressive these days with some units looking like something out of a concept car showroom. Some are square and boxy while others are sphere-like in their design. Two-piece toilets like the kind you find in most houses and rental properties have a predictable structure and appearance. This makes it easy for manufacturers to design bidets that will be a near-universal fit for this type of toilet.
When making a bidet to fit as many toilets as possible (like in an RV or where it’s really tight), it’s nice to know that most toilets are about the same size and have around the same bolt hole widths and that these dimensions remain consistent over time.
Fewer Two-Piece Toilets Are Skirted or Have Concealed Trapways
Like dimensions, this relates to the toilet design. However, this trait has to do with whether elements of the toilet are easy to get to.
On most two-piece toilets, bowl components like the trapway (the snake-like water passage) are typically in plain view. Other toilets (typically one-piece) conceal some or all of the toilet’s parts to give the commode a uniform appearance.
Some just hide the trapway but still maintain the natural shape of the toilet. Others, namely skirted toilets, cover most everything with a veneer that gives the toilet a seamless ultra-minimalist look.
Bidets are much harder to install on toilets with hidden parts. It’s usually harder to get to the fill valve and the mounting hardware that comes with a bidet is often incompatible with this design.
It’s the Most Common Toilet
I suppose this is just the flip side of the first advantage. I.e., because it’s the most common toilet design, bidet manufacturers include all the parts typically needed for a standard two-piece toilet setup.
Any Disadvantages?
There really aren’t any disadvantages specific to two-piece toilets when it comes to installing bidets.
But don’t forget to check whether your toilet has a round or elongated bowl design. Toilet bowls come as both round and elongated each with its own standardized dimensions. Also, here are some of the best bidets for elongated toilets.
As you’d imagine, elongated toilets are a bit longer—by a couple of inches or so. The extra couple of inches in length on elongated bidet seats renders them incompatible with round bowls.
There are plenty of bidets for round bowls, but a much wider selection seems to be available for the elongated kind.
Maybe it’s just me, but it seems that when I go to write a review or recommend a bidet, I’m far too often disappointed that the best model for a given population or application is only available for toilets with elongated bowls.
I don’t have any stats to confirm this, it’s just my experience.
Semi-Bidet-Friendly Toilets
Conventional One-Piece Toilets
If you have one, check out the article on the best bidets for one-piece toilets.
With one-piece toilets, the bowl and basin make up a single unit with fewer lines and crevices. They’re minimalist in appearance and look great with modern bathrooms.
One-piece toilets come in a much wider range of designs than their two-piece counterparts which is why I emphasize that “conventional” one-piece toilets can be bidet friendly.
Advantages for Bidets
The Fill Valve Is Often Accessible
Even when they’re skirted, you can usually locate the fill-valve at the back of the toilet. Instead of extending down from the bottom of the tank, they extend out. Sometimes, they’re in a hard-to-reach space but there’s usually a workaround. This brings us to the next point.
Special Equipment (Adapters, etc.) Exist for This Type of Toilet
If you find that you can’t access the components that you need to install the bidet, a lot of manufacturers make special products for this reason like adapters, extension hoses, and conversion kits.
Disadvantages
Even Conventional One-piece Toilets Are Often Flat in The Back
This puts less space between the back of the toilet and the wall which can make the bidet installation difficult. Even if the fill valve is in plain view, the space may be too cramped to fit the T-connector that came with the bidet.
There’s just not a lot of room between where the tank ends and the basin begins. There’s usually a slight contour that puts some space between the back of the toilet and the wall (it’s usually not completely flat). A lot of times, that space is sufficient. Otherwise, an extra part will be needed.
Some Are Too Wide Where the Bidet Attaches
This is much more of an issue with atypical ultra-modern toilet designs, but it happens with one-piece toilets too.
With one-piece toilets, the area around the back of the rim (where the mounting hardware is) often flares out to meet the tank. I’m not sure if there are any real functional reasons for this design, but it’s often the case.
On some models, the tank is “low-profile” meaning it is shorter and wider leading to more of a flair as the back of the seat spreads out to meet the tank. Sometimes this happens with tanks that aren’t low-profile.
On other models, a taller skinnier tank conforms to the width of the seat. Finally, sometimes the tank and basin are different widths but maintain the shape and contour of a typical two-piece toilet.
The latter two scenarios are ideal.
When a toilet is too wide in the back, the design prevents the installation of certain bidets. Specifically, bidets with control arms instead of remote controls can cause problems. This includes all bidet attachments (non-electric) and a lot of electric seats.
With seats, it depends on the position of the control arm. Sometimes the side panel is up and out of the way, so it doesn’t cause problems.
Issues with Mounting Hardware
Bidet seats come with their own nuts and bolts to attach the unit to the back of the toilet rim. The new hardware goes in the same bolt holes as the original seat. On skirted toilets, the bolts extend down into the unit (you can’t access them to thread the new nuts on).
The original mounting gear can often be used to install the new seat, but sometimes it’s incompatible for one reason or another. When that happens, you’ll need top mounting hardware.
Bidets Can Be Hard to Install on These Toilets
Remember, there is always a way. But you’ll find that a lot of bidets won’t fit these toilets without significant modifications. Some modifications require making permanent changes to the bathroom which can be unworkable for those in rental properties.
Full instructions for installing bidets on tankless and wall-hung toilets, check out the article on can you install a bidet on a tankless toilet?
Tankless Toilets (Flushometer)
Flushometer toilets are truly tankless and thus don’t rely on gravity from a cistern. Rather, they’re installed in buildings with extra powerful plumbing that can clear a bowl without the help of a tank. By lacking a tank, you don’t have external access to the water connection needed to attach the T-connector.
Water runs from behind the wall (in the plumbing) straight into the flush valve, so you can’t access the water until it’s already swirling in the bowl.
I wrote an article recently on how to install bidets on tankless toilets using special gear. So, it is possible. But it requires extra parts and that your bathroom be set up a specific way. The sink and toilet need to be close enough and can’t be on opposite sides of the wall. Any vanity in the way would probably need to be drilled into.
Also, the alternative installation methods don’t work on electric bidets—only attachments and handheld sprayers.
Concealed Cistern (Wall-Hung) Toilets
Some toilets look tankless but have a cistern (water tank) hidden behind the wall. The same issues with the flushometer extend to this kind as well. Whether a toilet is tankless or has a hidden tank, the water can’t be accessed on the toilet side of the wall.
The only way around this is to work with a plumber to have a shutoff valve installed next to the toilet or to use the method described in the article on tankless toilets. The former may not be feasible for your bathroom, but if you have a shutoff valve installed, it will allow for using electric bidet seats (the other method is limited to attachments and sprayers).
Fancy One-Piece Toilet Designs
Again, some one-piece toilets pose zero problems and others can be worked with. But the one-piece design is most common with toilets made for ultra-modern bathrooms. And this type of toilet can come in odd shapes, sizes, and dimensions.
Issues you can run into include:
- The bolt hole width is too far apart. In the US, the standard width is around 5.5”. While a huge majority of toilets conform to that range, some one-piece toilets have almost twice the width (I’ve seen bolt holes as far apart as 10” apart). The mounting bracket that comes with most bidets is adjustable (e.g., 5-7”) to give you room to work with but not that much.
- French curves. Some one-piece toilets are designed to have the tank slope down to meet the seat. Sometimes the corners or edges can get in the way of installing a seat or attachment. Other times, the area behind where you sit is rounded such that the bidet can’t fit.
- Odd shapes. The toilet is a strange shape that interferes with the installation of the bidet.
- Other issues. Given that one-piece toilets are usually skirted, you may run into the problems that were outlined earlier—not being able to access the fill valve, the toilet being too close to the wall, incompatible mounting hardware. These problems are correctable but will only add to the headache.
Can a Bidet Be Added to an Existing Toilet? Conclusion
That should sum it up.
Bidets can be installed on an existing toilet. The only exception is when there is when there’s no external access to a water connection. Regular two-piece toilets are always compatible. One-piece toilets and tankless designs pose more problems. When a problem arises, there’s usually a workaround.
This is an important question for a few reasons. At one end of the spectrum, it’s often assumed that a toilet with a bidet must have been made from the beginning with a built-in bidet. That is the case for some commodes—what they call toilet-bidet combos.
But the vast majority of toilet bidets are added to existing commodes. Toilet-bidet combos are probably the least common bidets because you have to pay for the entire commode. Bidet seats are awesome, especially the electrically powered kind. All the bidet technology present in a $5K toilet can be instantly transferred to a humble two-piece commode from the 1960s.
On the other end of the spectrum, it’s sometimes assumed that any bidet fits any toilet. As pointed out above, this is not the case.
Also, there’s always the portable option. If you have a wall-hung or tankless toilet and can’t use one of the alternative installation methods, some portable/travel units work just as well as some attachments and seats.
Thanks for reading.