The 3 Best Bidets for a One Piece Toilet 2023

A nice one-piece toilet

Today we’re looking at the best bidets on the market for one-piece toilets. This unconventional toilet design offers several advantages, but wide-ranging compatibility with bidets isn’t one of them.

The overall best bidet for a one-piece toilet is the TOTO C100. It has a control arm that’s positioned up and out of the way in case a one-piece toilet is extra wide in the back (low-profile tanks, etc.). The Cascade 3000 is the best for one-piece toilets with French curves.

Our Top Pick
TOTO C100 Washlet

Great overall pick for one-piece toilet, a combination of quality features for a reasonable price.

  • The position of the control arm
  • Warm water flow
  • Warm air dryer
  • Adjustable nozzle
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Finally, the best luxury option for one-piece toilets is the TOTO K300.

For one-piece toilets that are skirted, all three models just listed are compatible with 3/8″ T-valves for connecting to the shutoff valves.

It so happens that there are a couple of dimensions that are restricted by this type of toilet. With attachments, the control arm can get in the way, but that’s not always the case.

Of course, handheld bidet sprayers are located out to the side of toilets, so they’re compatible with the widest range of toilets—elongated vs. round, one-piece vs. two-piece, etc.

So, you’re very astute for doing your research because it’s probably not obvious to most people that one-piece toilets would be less compatible with bidets overall.

The Best Overall Bidet for One-Piece Toilets

The TOTO C100 Electric Bidet Seat

This bidet is the best overall for the vast majority of one-piece toilets but is not suitable for toilets with French curves (a rather uncommon design). If yours has French curves, then see the next section.

The absolute best bidet for one-piece toilets is the TOTO C100 (Amazon link).


  • The position of the control arm. If you look at the above picture, you’ll see that the control arm is positioned forward and higher up (it’s not flush with the back or bottom of the bidet). All bidet attachments (non-electric) and some electric seats come with a control arm (or control panel) instead of a remote control. In many cases, the control panel is positioned just below the seat. The problem is that one-piece toilets are sometimes too wide in the back (where the tank meets the basin) getting in the way of the control panel. The control panel may look like a remote control but they’re fixed to the side of the seat and thus permanent. At the very least, you want a control arm that’s flush with the bottom of the seat. In the case of the TOTO C100, it’s actually lifted up which is ideal.
  • Warm water flow. Electric seats may look similar to some non-electric bidets, but the latter can’t provide warm water unless certain plumbing equipment is used—equipment that requires either having a bidet hose permanently dangling from your faucet or making permanent changes to the property (something renters can’t do). This model uses a heated reservoir to keep warm water on tap for when you need it. The water gets warm but not too hot so you don’t have to worry about scalding yourself.
  • A warm air dryer. While some non-electric bidets can be modified to spray warm water, none are equipped with a dryer. Having a warm air dryer means you don’t need to dry off with toilet paper or a towel. This means saving money and less chaffing. Folks who use bidet attachments, sprayers, and standalone European bidets have to dab dry after each session with TP or a dedicated bidet towel.
  •  Frontal/feminine cleansing. A lot of bidets (both electric and non-electric) lack frontal wash capability, which is crazy given that half of adult consumers are women. With the C100 you can clean both the front and rear so it’s great for feminine hygiene.   
  • Adjustable nozzle/ability to aim. Newcomers to the subject often wonder how on earth bidets get the water where it needs to go. Well, bidets vary in the ability to do it. The control panel on the C100 allows for precision aiming of the wand to make sure you get an accurate clean every time.
  • A retractable wand that’s self-cleaning. Retractable wands are standard on toilet bidets, even non-electric models. And that feature alone is useful. Having the nozzle out of the way (secure in its housing) when using the toilet means it won’t be as likely to get soiled. But, anything that stays in the toilet has the ability to get contaminated with dirty water over time. The wand on the C100 sanitizes itself which further helps the bidet stay clean.
  • Slow-close lid. This is a cool feature. If you’re like me, you often forget to close the lid before flushing. I’ve found that having a slow-close lid has made it easier to keep the lid shut because you only have to give it a small nudge when standing up. Keeping the toilet closed helps keep the bowl clean and prevents the dispersion of contaminated water into the air/onto surfaces when flushing.
  • A water filter. I’m sure there are a few non-electric attachments out there that offer warm water, but it’s not a standard feature on bidet attachments.  Toilet bidets reroute water to the nozzle that would normally go straight to the tank. Where electric and non-electric bidets differ is that the former (including the TOTO C100) tend to filter the water before sending it through the nozzle. This is great for preventing UTIs and other infections.
  • A self-cleaning toilet bowl. The TOTO C100 has a built-in sensor to detect when the user sits down. When triggered, the bowl is sprayed or “pre-misted” with a cleaning solution that keeps excrement from sticking to the inside of the toilet.
  • Heated seats. You don’t need the $1000 Cadillac of electric bidets to get heated seats. Having a heated seat on a toilet may sound excessive and unnecessary, and I’m sure for a lot of folks it is. But for those who struggle with constipation, heated seats help relax the user so that things can get moving again. They’re great for relaxation, in general, regardless if you suffer from constipation.
  • Great brand. There are tons of cheap knockoffs out there. TOTO has been around the block and they have a long history of putting out quality products that get good feedback. Having a quality seat is very important because cheap models are known for leaking.


  • Limited warm water supply. As mentioned, this model uses a heated reservoir. This type of heater warms the water that’s in the reservoir meaning that when the water runs out, a new batch has to be heated. There’s usually enough in the reservoir for a good minute of warm water cleaning. Getting a continuous flow of warm water usually requires purchasing a luxury model which can be significantly more money. A minute of warm water is plenty for most bowel movements. If it runs out mid-wash you can always finish up with cool water—something that’s the default for bidet attachments.

The Best Bidet for One-Piece Toilets with French Curves

Dignity Solutions Cascade 3000

The Cascade 3000 Bidet Seat

You can check out the current prices here (Amazon link).

Putting a typical bidet seat on a toilet with French curves can be like forcing a square peg in a round hole.

While electric bidets are usually compatible with one-piece toilets, commodes with French curves can be an exception.

With this design, a couple of problems can arise:

  1. Bidet seats are almost always flat in the back and thus too wide.
  2. The mounting bracket (used to install the bidet) often won’t sit flush behind the toilet rim.

With French curves, the toilet behind where you sit (the tank and where it meets the seat) is usually rounded or indented. The back of bidet seats, usually being flat, won’t fit.

Notice how the original toilet seat is rounded to fit nicely.

This means the bidet seat can’t be positioned far enough back on the toilet for the bolt holes to line up.

This can result in an overbite.

Side view of toilet with French curves. Notice how the contour of the toilet keeps the bidet from sitting all the way back. It looks like an alligator.

Keep in mind that the Cascade 3000 can still have a bit of an overbite depending on the model of toilet–not always but sometimes. In any case, this model will probably provide the closes fit you’ll find.

Sometimes this area of the toilet (where the tank and seat meet) isn’t rounded but has corners. This can still pose problems, because the two parts that slope down are too narrow for the back of the seat, meaning you still can’t reach the bolt holes.

This brings us to another problem: the mounting bracket.

Mounting brackets are used to help bidet seats fit universally with the bolt hole widths on most toilets. 

The mounting bracket that comes with bidet seats is typically rectangular in shape. When the toilet tank is rounded in the back, the mounting plate won’t sit flush behind the rim.

The above recommended bidet fixes both problems.

Pros of the Cascade 3000

  • The bidet seat is rounded in the back. Instead of having corners, the back of this seat curves smoothly to allow it to fit between the corridors created by the French curves. For this reason, it is a great fit for both one- and two-piece toilets with or without French curves.
  • A curved mounting bracket. The bracket sits flush on the back of the toilet rim. Hence, it will line up with the bolt holes on nearly any modern toilet.
  • Unlimited warm water supply, great for shared bathrooms. While a minute of warm water is usually all that’s needed to get a good wash, having a limitless warm water supply does have its perks. For one, if you share a bathroom, it won’t matter how long it’s been between toilet uses. Even if you’re normally good with a minute of washing, the water may run cold on the next person to use the toilet if there isn’t enough time to heat up another batch of water between uses. This model has an instantaneous-type water heater, a feature usually reserved for luxury seats.
  • Better for feminine cleansing. This model comes with a feminine wash mode. While the TOTO C100 offers frontal cleansing, it doesn’t have a frontal wash mode meant for feminine hygiene. This is probably because, to have a good feminine wash mode, you really need unlimited warm water. For one thing, women often report cleaning the front and back in one session, which means at least twice the water would be needed at one time. Secondly, some protocols for deep cleaning of the frontal region (e.g. douching) are much longer than a minute. Anyway, this model has a feminine wash mode and the warm water to back it up.
  • A remote control. Remote controls are usually considered a step up from the panels fixed to the side of more affordable seats. It’s usually more of an aesthetic thing but, in this case, it’s an especially useful feature because the remote is sure to be out of the way during installation.
  • Sittable lid. Most toilet lids made of plastic—even high-quality plastic—are not designed to be sat on. Porcelain lids are always sittable, but it takes an especially sturdy construction to make plastic toilet seats suitable for sitting. Bidets are made with a wide range of materials these days, with some being more durable than others. The seat on the Cascade 3000 supports up to 300 lbs (~136 kg).
  • This model comes with many of the above-mentioned perks: warm air dryer, adjustable wand positioning, retractable and self-sanitizing nozzle, slow-close lid*, heated seats, water filter, and trusted brand.

*I’ve seen it mentioned online that the Cascade 3000 has this feature but didn’t see it listed on the main site.


  • Price. It may or may not be advertised as such, but this bidet is on the luxury end of the spectrum. It has most all the bells and whistles that have come to be expected from modern electric bidets and this is reflected in the price which is on the higher end. But, it’s not nearly as expensive as some of the other luxury bidets I’ve seen.
  • No self-cleaning bowl. This model doesn’t seem to have a self-cleaning bowl. This shouldn’t be an issue. If you’re having a hard time finding a bidet that fits your toilet, then foregoing the self-misting function is a small sacrifice to make.

The Best Luxury Bidet for a One-Piece Toilet

The TOTO K300

Best Option for the Money
TOTO K300 Washlet

I can’t recommend this bidet enough. It offers way more features than most bidets at this price point.

Adjustable Features:

  • Water Temp
  • Water Pressure
  • Heated Seat
  • Dryer Temp
  • Nozzle Position
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For those who don’t have a toilet with French corners but want an affordable high-quality bidet that provides continuous warm water, I’d go with the TOTO K300 (also available on Amazon).

It has all the standard features of the C100 but comes with a continuous warm water heater.

You could go with the Cascade 3000 just mentioned. It has about everything you’d want in a modern electric bidet and it’s the model most likely to fit a wide range of one-piece toilets, both those with and without French corners.

But, the main thing that sets luxury bidets apart from the rest is the instantaneous-type water heater. If you don’t have French corners, then then you don’t need the Cascade 3000 and there are more affordable options out there.

Pricewise, the TOTO K300 is about average for entry-level luxury bidets. You could pay a lot more, but there are diminishing returns past a certain point.

Potential Problems with One-Piece Toilets

One-piece toilets can pose problems for attachments. I hate to recommend a specific one here because there’s a good chance it won’t fit your toilet. You’re much better off reaching out to the manufacturer with the specs of your current toilet to see which one would best fit.

The issue is that some one-piece toilets are too wide in the back.

Too Wide In the Back for Bidet Attachments

Sometimes, one-piece toilets have low-profile tanks that are shorter and wider. Because the tank and basin are one unit, the back of the seat often flares out to meet the tank. Other times, they just flare out too much in the back (even with normal tank dimensions).

If you’re a minimalist and would prefer to get a bidet attachment, fear not. Most should be able to find a compatible attachment with a bit of research.

You’d be best off reaching out to manufacturers with the dimensions of your toilet so they can tell you for sure if any of their attachments will fit.

While they offer few features, they are a thousand times better than toilet paper.

We touched on it above when discussing the control arm of the TOTO C100, but 1-piece toilets can often conflict with bidets that have components that stick out to the side.

One-piece toilets are incompatible with bidet attachments when the toilet is too wide in the back.

With this type of toilet, the basin/bowl is attached directly to the tank. This isn’t always a problem, but many designs have the rim flair out to meet the tank which causes the rear to be wider.

Notice the difference in width at the back of the rim.

Trying to put one on would look something like this:

Notice how the bolt holes don’t line up.

Note that this is not quite the same issue as the French curve problem mentioned earlier.

Toilets with French curves are often too wide in the back, but the reverse isn’t necessarily true. Plenty of one-piece toilets are designed to have the rim and tank meet at a 90-degree angle without the tank sloping down to meet the basin.

However, having French curves could rule out a lot of bidet attachments because the part of the tank that slopes down to meet the seat would interfere with the installation.

Skirted Bowls and Concealed Trapways

This issue can be overcome with the right parts–usually, an extension hose or a T-valve for skirted bowls.

It seems most one-piece toilets have a skirted bowl design or at least a concealed trapway. A skirted bowl covers all of the toilet’s inner workings to provide a clean minimalist look. Concealed trapway designs just cover the trap (the s-like water passage on the side of toilet bowls).

Both designs can make it more difficult to get to the fill valve on the toilet and skirted designs sometimes require special top mounting hardware to install the seat over the attachment.


That should do it.

Electric bidet seats tend to fit one-piece toilets because they sit atop the rim and don’t interfere with installation. However, French curves can be an exception. Bidet attachments can be problematic because one-piece toilets are often too wide in the area where the tank connects to the bowl.

So, in this article, we looked at the best bidets on the market for one-piece toilets, and which categories of bidets work well, in general, with this type of toilet.

Those who are wise enough to research bidets for one-piece toilets probably understand the elongated vs. round distinction. Some toilets are oblong while others are round. All of the models above should be available in round and elongated versions. For more info, check out the article on the best bidets for elongated toilets.

There’s a lot of conflicting info out there on which models are compatible with which types of commodes. I’ve spoken to several bidet manufacturers who’ve given me lists of their models that work with one-piece toilets.

The same thing kept happening. I’d get the list of “compatible” bidets only to find that after reading a few reviews, there would usually be a customer or two who claimed the model didn’t fit.

This is because toilets can vary in so many dimensions. And even when dealing with the same model of toilet, the stylistic design can vary from year to year.

In writing this article, I wanted to give recommendations that would be as universal as possible working with the widest range of one-piece toilets. I really want to save you the trouble of ordering a unit and attempting the installation process only to have to return it a day later.

Anyway, I hope you found that helpful. Thanks for reading.

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