How Does A Tankless Toilet Work?

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Last Updated on December 30, 2022 by acechapman

To flush a toilet, you need to pour large quantities of water into the bowl. A toilet tank is a necessity because most homes do not have enough pressure. However, you might not be aware that public toilets, and especially urinals, do not contain a tank. A tank is not required for modern residential toilets. How does a tankless toilet work? Let’s find out.

What is a Tankless Toilet?

A tankless toilet is a type of toilet that does not have a traditional water tank mounted on the back of the toilet bowl. Instead, it uses a small, high-pressure pump to quickly flush the waste down the drain. Tankless toilets are designed to be more efficient and use less water than traditional toilets.

One of the main benefits of tankless toilets is their ability to conserve water. Traditional toilets can use up to seven gallons of water per flush, while tankless toilets typically use only 1.28 gallons or less. This not only helps to reduce water consumption, but it can also lower your water bill.

In addition to being more water-efficient, they are also more space-efficient. Because they don’t have a water tank, they can be mounted closer to the wall and take up less space in the bathroom. This can be especially useful in small bathrooms or for homeowners looking to maximize the space in their bathrooms.

Despite their many benefits, tankless toilets do have some drawbacks. They can be more expensive to install than traditional toilets, and they may require more maintenance over time. Additionally, they may not be as effective at flushing large amounts of waste, so they may not be the best choice for households with young children or individuals with medical conditions or disabilities.

Overall, tankless toilets are a great option for homeowners looking to save water and space in their bathrooms. While they may have a higher upfront cost, they can save money on water bills.

how does a tankless toilet work

How Does A Tankless Toilet Work?

A tankless toilet works by using a small, high-pressure pump to quickly flush the waste down the drain. When the toilet is flushed, a sensor inside the toilet bowl activates the pump, which pushes water into the bowl and down the drain.

Tankless toilets do not have a traditional water tank mounted on the back of the toilet bowl as traditional toilets do. Instead, they use a pressurized water supply line to provide the necessary water for flushing. This water supply line is typically connected to the main water supply line for the home.

When the toilet is flushed, the pump pressurizes the water supply line and forces water into the toilet bowl. The water then flows down the drain and into the sewage system. The pump is designed to operate quickly and quietly, so it does not make the loud flushing noise that traditional toilets do.

Tankless Toilets vs Tank Toilets

Let’s first understand the basics of a tankless toilet and how does it work in comparison to tank toilets.

Gravity flush toilets are also called tank toilets. The reason is that the tank houses the toilet tank, and water flows through it to the bowl by gravity during flushing. Tank toilets are not like tankless toilets. They do not require electricity to operate.

The shutoff valve connects the toilet tank to the main water supply. This ensures that the tank is always stocked with water and ready for flushing.

Tank toilets require different amounts of water to flush the toilet. Older models may use up to 3.5 gallons per flush, while newer models use either 1.6 or 1.28 Gallons per flush.

To flush a tank toilet you need to pull the trip level located at the front of the tank. Dual flush toilets have buttons at the top of each tank.

The flush valve is an opening in the bottom of the tank that allows water to drain out and into the bowl. The toilet flapper seals off the flush valve, allowing for the tank to refill.

A flushometer is a device that flushes tankless toilets. Every time you press the flushometer, a metered volume of water is released.

Some smart tankless toilets in residential settings have an automatic flushing system, while others use a wireless remote control. You can also combine both functions.

Tankless toilets are less likely to leak than toilet tanks and require less maintenance than tank toilets. They can also be compacted, making them great for small bathrooms.

Tankless Toilets vs Pressure-Assisted Toilets

It is not appropriate to compare tankless toilets with pressure-assisted ones. Some toilets have a pressure-assisted flushing system but they are not the same as pressure-assisted toilets.

Pressure-assisted tank toilets have the same appearance as gravity toilets, but they don’t rely 100% on gravity to flush. A secondary tank is located inside the main tank and is called a pressure vessel.

The water from the supply line flows into this pressure vessel, where the air is trapped and compressed. The tank is then under pressure.

The pressure water from the toilet flushes into the bowl. Once the bowl is full, the pressure vessel starts the process again. Pressure-assisted toilets can be louder than regular gravity flush toilets.

People who want to install read-displacement toilets will find it easier with pressure-assisted toilets. Rear discharge toilets allow waste to exit the toilet from the rear, rather than the floor.

Rear discharges, also known as rear outlet toilets, have a shorter trap that isn’t enough to trigger a strong enough siphon action. To give them extra power, pressure-assisted toilet systems are available.

Tankless Toilets vs Wall-Hung Toilets

Wall-hung toilets are another type of toilet, which should not be confused with tankless toilets. Also known as wall-mounted toilets. Although they look more like they are tankless, they actually contain a tank.

Wall-hung toilets can be mounted on the bathroom walls, unlike floor-mounted toilets. The toilet tank is hidden in the bathroom wall so that the bowl can be seen.

A carrier, or frame, is used to install a wall-hung toilet. It is attached to the bathroom wall. This carrier is used to carry the toilet tank. It is also the place where the bowl is attached using long bolts.

A secondary wall is built inside the bathroom to conceal the tank and carrier. Only a small opening is left where the flush buttons are located. In case of any repairs, this opening allows you to access the toilet tank.

Tankless toilets can be installed on the floor, unlike wall-hung toilets. They do not require a tank carrier or the construction of a secondary bathroom wall.

how does a tankless toilet work

Advantages & Disadvantages of a Tankless Toilet

The following are the advantages/disadvantages of installing a tankless toilet over a tank toilet.

Advantages of Tankless Toilets

Space Efficient

A tankless toilet can be installed in a small bathroom and does not look cluttered. A tankless toilet can make even a small bathroom seem larger. The extra space can be used to improve the decor of your bathroom.

Tank toilets are generally wider than tankless toilets due to the tank. This makes them more expensive. Tankless toilets are also shorter than tank toilets because they don’t have a tank.

Tankless toilets are a great choice for those with smaller bathrooms.

Flushes Faster

After every flush, you must wait for the tank’s refill before you can flush again in a tank toilet. Even worse is if you don’t have enough waste to flush, and then you must wait for the tank refill to allow you to flush again.

Tankless toilets don’t need to be refilled. They can be used at any time. Tankless toilets are the best option for bathrooms with multiple users.

Powerful Flush

You never know if the first flush of a tank toilet will work or not. Wait for confirmation.

A tankless toilet eliminates the need to clean up after a flush. The water pressure is strong enough to push all waste out of the trap and down the drainpipe.

Sleek Design

It is possible to find sleek tank toilets. However, tankless toilets are more expensive. These toilets are stylish, modern, and elegant and will complement any bathroom design.

As mentioned before, residential tankless toilets have bidet seats. These seats are just as beautiful as the toilets. Bidet toilet seats are stronger than regular toilet seats and fit perfectly into the toilet, further increasing their beauty.


Owners of tank toilets will have to deal with issues such as a constantly running toilet or a leaking toilet. The toilet tank is the source of all these problems.

These problems are virtually eliminated when you use a tankless toilet. The bowl measures the water entering it and is therefore precise without the risk of it leaking.

Leaking or running toilets are not only harmful to the environment, but also to your wallet.

Lesser Problems

There are many parts in a toilet tank that can fail or wear out, and sometimes it is necessary to replace them. Tankless toilets are less complicated to repair because they have fewer parts.

Fewer problems mean fewer repairs. Tankless toilets have few moving parts so owners don’t have to worry about wear and tear.

A tankless will last you a long time before you need to maintain it.

Easy Cleaning

A tankless toilet is smaller than a tank toilet. The tankless toilet can be cleaned and maintained quickly and easily.

They have no place to hide dirt, and their bowls are almost always fully surrounded. Tank toilets are not always this way. It is difficult to clean the gap between the bowl and tank in two-piece toilets.

Disadvantages of Tankless Toilets

What are the drawbacks to installing tankless toilets in your home? These are just a few:

Electricity Dependent

To power the water pump, tankless toilets must be connected to an electric outlet. You can flush the toilet only with water and electricity.

You may not enjoy the convenience of a tankless toilet if you live in an area that is susceptible to power outages. A standby generator may be necessary, but it is often expensive.

Installing a tankless toilet will result in higher power bills. The power needed to run the toilet will not only be sufficient to supply the water but the seat of the bidet must also be connected to the power in order to perform its functions such as hot water cleansing, warm-air drying, heated seat, and nightlight.


A tankless toilet flushes water out of the toilet and forces it to clean. They can be quite noisy as a result. Before they can be installed, this must be taken into consideration.

For the first few days, you may be concerned by the noise but you will soon get used to it.

Not Easy To Repair

A gravity flush toilet can be fixed in minutes. Tankless toilets are more difficult. To resolve any problems, a professional plumber will be needed.

They are more expensive than a tank toilet’s replacement parts, and they are not as readily available.


Tankless toilets are more expensive than gravity flush toilets. These are not surprising considering all their features compared to gravity flush toilets.

The Toto Ultramax II is a comparable toilet. Compare it to the Toto Neorest 75H tankless toilet. The Toto Neorest 750H costs more than 10x that of Ultramax II.

However, there are tankless toilets that are cheaper, especially those without bidets.

Tankless Toilets For Small Bathrooms

Are you looking for a small tankless toilet to fit in your bathroom? The Saniflo 023 Sanicompact self-contained toilet is the best choice for small bathrooms.

It measures:

  • Depth: 21.5 inches
  • Width: 14.5 inches
  • Height: 18.5 inches

The toilet can be placed in a basement or a bathroom that is not near the sewer line. It is a tankless toilet that can also be used as an upflush and a rear outlet toilet.

Tankless toilets can be installed as far as 9 feet below the sewer line and up to 120 feet from the sewer line. It is possible to add a sink or connect its gray water to your toilet output system.

This toilet is even more convenient because it doesn’t require a floor drainage system. This makes it easy to install a bathroom almost anywhere.

This post, which I wrote a while back, compares this toilet to other tankless toilets.


In the past, tankless toilets were more popular in public toilets than at home. These toilets are now a popular choice due to their convenience and comfort.

Now you know the answer to the question, “How does a tankless toilet work?”. Overall, you can decide whatever suits your needs. If you have the money to purchase one, then go ahead. These toilets are the future.

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