Siphonic Vs. Washdown Toilet – What’s the Difference?

When building a lavatory, both Siphonic and Washdown toilets are super popular. But each toilet has something different to offer; hence, it’s normal for you to feel confused.

That’s why I’ve come up with this ultimate Siphonic Vs. Washdown toilet guide. Once you go through this, you’ll know which one is perfect for your washroom. So let’s get started, shall we?

Siphonic Vs. Washdown Toilet – Everything You Need to Know!

When you press the flush in your toilet, the force of rushing water clears the waste from the bowl. But different fixtures use different mechanisms to do that. Let’s look at the types of flushing systems you’ll see in the market.

  • Single Flush
  • Siphon Jet Flush
  • Gravity Washdown flush
  • Vacuum Flush
  • Rear toilet flush
  • Dual Flush
  • Flapper flush
  • Double cyclone flush
  • The tornado flush

Though you can get tons of types, today we’ll talk about the Siphon and Washdown flushes in the following sections.

Let’s get into that part right away.

What Is a Siphonic Toilet?

The Siphonic toilet is designed with a narrow S-shaped trapway. And for this slender trap-way design, the toilet bowl is smaller than any other system.

Furthermore, you’ll see a higher water lever inside the bowl, and these fixtures come with a longer height. For this reason, there’ll be water splashes or dirty spots on the toilet.

One of the best things about these toilets is that they’re made with a fully glazed trapway. Thanks to this, all the waste can be washed away with a strong single flush.  

How Does a Siphonic Toilet Work?

This toilet system uses a vacuum to draw the waste from the bowl to the trapway.

The S-shaped trapway acts like a siphon and makes this whole thing possible. The lever gets pulled when you push the flush button, and water comes from the flush valve.

The water reaches the toilet bowl in two ways. Firstly, the stream comes through the holes around the seat rim.

And then, the siphon jet-hole shoots water into the bowl to create the siphoning effect. When the whole procedure is done, your toilet will be super clean.

Good Sides and Drawbacks of Siphonic Toilets

The Siphonic toilets are one of the most efficient ones; there’s no doubt about that. But they’re also one or two drawbacks you should be aware of.

So here’re the advantages and drawbacks you’ll get after installing this fixture.

Good Sides

  • You don’t need more than one flash to clear the toilet bowl
  • A higher water level keeps the bowl clean and odorless
  • Ensures fewer skid marks
  • Offers a quieter flush


  • The narrow trapway tends to get clogged if not maintained frequently

What Is a Washdown Toilet?

The Washdown toilets use a simple mechanism; they just use the gravitational flow and weight of the water to remove the waste from the bowl. It’s one of the most used types of toilets in Europe.

These fixtures are designed with a wider trapway. As a result, the powerful water pressure surges from the tank. The trapway is wide, so you can easily get rid of the waste quickly.

However, Washdown toilets are shorter in height; hence, the water level will be lowered. Well, people who want clog-free plumbing; tend to go for this particular type.

Good Sides and Drawbacks of Washdown Toilets

Yes, it’s one of the best toilets you can get for your compact washrooms. Also, it’s a water-efficient option. But there’re some disadvantages also, so let’s learn about those too!

Good Sides

  • The whole toilet is compact thanks to its height
  • Wide trapway ensures a clog-free experience
  • Can handle heavy loads of solid waste without any trouble
  • The dual flushing option makes it a water-saving fixture
  • Easy to maintain


  • The lower water level can leave skid marks
  • You may need more than one flush to clean the bowl

Siphonic Vs. Washdown Toilet – The Differences

Siphonic and Washdown; both these toilets are pretty common among people. But everyone has their preference when it comes to decorating their washroom. So here’s a detailed comparison of these two fixtures that will help you to make the right decision.

FeatureWashdown ToiletSiphonic Toilet
Trapway TypeWideNarrow
Bowl Base TypeCompact and shallowWide and elongated
Bowl Base SizeSpace-savingQuite Large
Water SurfaceLow water levelHigh water level
Clogging TendencyDoesn’t get clogged oftenVulnerable to clogging
OdorNot tolerableTolerable
MaintenanceLow MaintenanceHigh maintenance

Bowl Size

The Siphonic toilet needs a wider bowl to fill it with water and proper flushing. Hence, it’s a better choice for spacious bathrooms.

On the other hand, the Washdown toilet has compact bowls as it uses a gravitational stream and a lower water level. If you have a smaller lavatory, try the Washdown ones for a better experience.


Siphonic toilets come with a signature s-shaped trapway to make the mechanism work. For this specific design, these toilets are comparatively higher.

And when it’s about the Washdown fixtures, the trapway is pretty wider but shorter. Well, it often causes water splashes while doing our business, so keep that in mind.

Outlet Size

While installing Washdown toilets, you’ll need an 8-12 inches outlet. But a minimum 12-inch outlet is required between the wall and center if you’re working with Siphonic fixtures.

Thus, if you have extra space in your bathroom, you can surely go for the Siphonic ones. Otherwise, Washdown will work best for you.

Water Efficiency

The Washdown toilet is often made with two buttons. You can press the smaller one for lighter wastes and push the bigger button for solid waste. But the Siphonic ones won’t give you any option like that.

Therefore, the Washdown fixture is definitely the water saver here; there’s no doubt about that.


The bowls of the Washdown toilets come with a shallow design. In addition, the water level will be minimal on that. Therefore, it’s prone to skid marks and bad odor. Hence, you may need to clean it more often.

On the other hand, the higher water level on the Siphonic toilet bowl will prevent skid marks. But the narrow trapway can get clogged pretty easily.

Well, you can see, when it’s about maintenance, both of these fixtures can give you some hard times. So pick the one according to your liking.

Frequently Asked Questions

1.    Which flushing system is best?

It’s considered that the pressure flushing systems are the best ones you can get. This system uses a powerful water stream to clean all the gunk; no residue will be left on the bowl.

2.    What toilet is the best for not clogging?

If you’re concerned about clogged toilets, you can use a Washdown fixture. Thanks to the wide trapway, this toilet is less likely to get clogged.

3.    How do you unblock a Siphonic toilet?

Here’re the steps you can follow to unblock your Siphonic toilet.

  • First of all, close the valve to stop the water supply.
  • Now flush the toilet to get rid of the water from the bowl. If there’s anything left, use a sponge and soak everything up.
  • When drying up the toilet bowl, inspect the jet for blockages. Take a flashlight and peek into every hole. If the clogs look dark or orange, you should blame bacteria for that.
  • After inspection, take duct tape and seal all the jets. And then, pour vinegar and baking soda into the water tank. When that part is completed, move on to the siphon jets.
  • There’s a black overflow pipe on the water tank. If you fill that with vinegar and baking soda solution, it will go through every jet. To make the solution, take one-third baking soda and two-thirds vinegar; it’s the ideal amount.
  • After pouring the solution, let it sit for at least an hour. And then, you can take out the duct tape open the fill valve, and flush the toilet. You can use a toilet brush to scrub off all the gunk if there’s any stubborn residue.

4.    What is washdown flushing?

The toilet that uses water weight and gravitational force to eliminate waste is known as Washdown flushing.

5.    Are siphon Jet toilets better?

According to many users, the Siphon jet toilets are better than the others. This system cleans the bowl in one flush and has less odor and skid marks. So yes, you can call it a better option.

6.    What is Siphonic toilet flushing?

The flushing system that uses a vacuum to clean the waste is known as the Siphonic toilet. It’s quite popular, but you’ll need a spacious place to install it.

Wrap Up

You can easily go for the Washdown one if you have a spacious bathroom. Yes, you may have to go the extra mile to keep it squeaky clean.

By contrast, the Siphonic toilets are a better option for spacious lavatories. And it doesn’t get dirty that easily; that’s a bonus.

So you can see there’s no specific winner when it comes to the Siphonic vs. Washdown toilet. Each fixture offers different benefits and has its own drawbacks.

Therefore, you need to choose the right one according to your preference; that’s it.

Hello, I'm Jon C. Brown, an expert in the field of toilets. With over 15 years of experience in this industry, a significant portion of my life has been devoted to crafting high-quality toilets and bathrooms. Consequently, I've received countless inquiries about the toilet and bathroom industries. That's why, I've launched this website to provide top-notch solutions for all your toilet and bathroom related needs.

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