When you shop for Fluid or Caroma toilets, two words keep coming up: siphonic and washdown. They describe how a bowl moves waste. Fluid and Caroma are a useful pair for comparing the two, because Fluid's lineup leans siphonic and rimless while Caroma's Caravelle family is washdown. This guide explains the difference and lists the models we carry in each camp.
Specs here come from the manufacturers' specification sheets and our product pages. We've left out marketing claims we couldn't verify. Browse the brands on our Fluid and Caroma brand pages.
Siphonic vs Washdown: The Short Version
Siphonic toilets
A siphonic bowl has a curved, fully enclosed trapway. When you flush, water filling that trapway creates a siphon that pulls the bowl contents out. Siphonic bowls usually hold a larger water surface in the bowl. Siphonic is the most common design in North American toilets.
Washdown toilets
A washdown bowl uses the momentum of water dropping from the tank to push waste straight down through a wider, more direct trapway. There is no siphon. The water surface is usually smaller. The design is common in Australia and Europe, where Caroma comes from.
| Siphonic | Washdown | |
|---|---|---|
| How waste leaves | Siphon pulls it through | Water pushes it through |
| Trapway | Curved, enclosed | Wider, more direct |
| Typical water surface | Larger | Smaller |
| Flush sound | Often a longer "draw" | Often a shorter rush |
| In our range | Fluid Citi, Quad, Duo | Caroma Caravelle family |
Neither design is automatically "better". The right choice depends on your bathroom, your rough-in and which features you care about.
Fluid Siphonic Toilets We Carry
| Model | Type | Flush | Notes (per spec sheet/listing) |
|---|---|---|---|
| Fluid Citi Rimless One-Piece | One-piece, siphonic, rimless | Dual 1.28 / 0.8 gpf | 326202 soft-close seat included; ADA compliant |
| Fluid Quad Rimless One-Piece | One-piece, siphonic, rimless | Dual 1.28 / 0.8 gpf | Easy Height, elongated; 326202W seat included |
| Fluid Quad Siphonic Rimless Two-Piece | Two-piece, siphonic, rimless | Dual 1.28 / 0.8 gpf | 17-1/2" seat height to top of seat; 12" floor outlet; left or right lever |
| Fluid Duo Two-Piece | Two-piece, siphonic | Single 1.28 gpf | 12" floor outlet; left or right lever; 326203W seat included |
What "rimless" means
A rimless bowl has no hollow rim channel under the bowl lip. Water is directed around the bowl from the inlet instead. With no channel there, you have one less hidden spot to clean. The Citi, Quad one-piece and Quad two-piece are all rimless.
Fluid's listings show a 5-year warranty on vitreous china and 3 years on internal components for these toilets. Check each product page for the current terms.
Caroma Washdown Toilets We Carry
Caroma's Caravelle Smart family is washdown and dual flush at 1.28 / 0.8 gpf. Caroma's Smart Connect models use an offset outlet that Caroma says suits 10" to 12" rough-ins. That is a real advantage if your home has an older 10" rough-in.
- Caravelle Smart One-Piece 989900: push button, 17–19" seat height per Caroma's spec sheet
- Caravelle One-Piece 989100: lever
- Caravelle Smart Two-Piece (lever) and two-piece (button)
- Caravelle Smart Back Outlet: for wall drains
Our Caroma Caravelle guide covers each model in detail.
How to Choose Between Them
1. Start with your rough-in
Measure from the finished wall (not the baseboard) to the centre of the closet bolts. The Fluid siphonic models we list use a 12" floor outlet. Caroma's Smart Connect Caravelles cover 10"–12". If your drain is in the wall, the Caravelle back outlet is the only model here built for that. See our rough-in guide.
2. Decide on dual or single flush
Every model above is dual flush at 1.28 / 0.8 gpf except the Fluid Duo, which is a single 1.28 gpf flush. If you want a simple single lever, the Duo fits that brief.
3. Pick one-piece or two-piece
Both brands offer each style. One-piece models are easier to wipe down, and two-piece models are easier to carry in. Our one-piece buying guide has more detail.
4. Think about cleaning
If a rimless bowl appeals to you, look at the Fluid Citi or Quad. If a smaller water surface and a Smart Connect install suit your project, look at the Caravelle.
Adding a Bidet Seat
Both brands use elongated bowls on most models. The Fluid SSI bidet seat is listed as fitting most elongated toilets with a brass tee connection, and it needs a nearby outlet. Before you buy, compare its dimensions with your bowl. Our bidet seat explainer covers the basics.
Water Use: What 1.28 and 0.8 gpf Mean
Every model in this guide uses 1.28 gallons (4.8 L) or less per full flush. In the dual-flush models, the reduced flush uses 0.8 gallons (3 L). Older toilets installed before low-flow rules often used 3.5 gallons or more per flush, so changing an old toilet is one of the simplest ways to cut household water use. Several of these models are listed as WaterSense certified on the manufacturer's spec sheet, including the Fluid Quad two-piece and Duo. Many Canadian municipalities have offered toilet rebate programs over the years, so check with your city for current details.
Seat Height and Comfort
Fluid and Caroma both call their taller bowls "Easy Height". Fluid's spec sheet lists the Quad two-piece at 17-1/2" to the top of the seat. Caroma lists the Caravelle Smart one-piece at 17–19" to the top of the seat. A taller seat can make sitting and standing easier, especially for older adults or anyone with knee trouble. Our guide to toilets for small bathrooms also covers sizing.
Installation Notes for Either Type
- Use a new wax or foam ring every time a toilet is set. Never reuse the old one.
- Level the bowl before tightening the closet bolts. Over-tightening can crack vitreous china.
- Check the supply valve. A replacement toilet is a good time to swap an old multi-turn stop for a quarter-turn one.
- Follow the installation instructions linked on each product page, and hire a licensed plumber if you're unsure.
Bottom Line
If you want a rimless bowl with a siphonic flush and a 12" rough-in, start with Fluid's Citi or Quad. For a simple single flush, look at the Fluid Duo. If you have a 10" rough-in, a wall drain, or simply prefer the washdown style, the Caroma Caravelle family is the place to look. All of them are elongated, comfort-height designs with a soft-close seat in the box.
Sources: Fluid and Caroma specification sheets, the Caroma product pages (caromausa.com), and Plumbing Market product pages.
Frequently Asked Questions
What is the difference between a siphonic and a washdown toilet?
A siphonic toilet uses a curved, enclosed trapway that creates a siphon to pull waste out. A washdown toilet uses the force of water from the tank to push waste through a wider, more direct trapway.
Are Fluid toilets siphonic?
The Fluid Citi, Quad and Duo toilets we carry are listed as siphonic, and the Citi and Quad models are also rimless.
Are Caroma toilets washdown?
Yes. Caroma describes its Caravelle Smart toilets as washdown, dual flush models at 1.28 / 0.8 gpf.
Which toilet suits a 10-inch rough-in?
Caroma's Smart Connect Caravelle models are listed for 10-inch to 12-inch rough-ins. The Fluid siphonic models we carry use a 12-inch outlet.
What warranty do Fluid toilets have?
Our Fluid toilet listings show a limited warranty of 5 years on vitreous china and 3 years on internal components.
