Rear Outlet Toilets: Everything You Need To Know


When it comes to toilets, we often think of the conventional floor drain outlet that has become the standard in most households. However, there’s another type of toilet that deserves attention: the rear outlet toilet. While rear outlet toilets are not as commonly known or used, they offer unique advantages and are a perfect solution for specific plumbing setups. In this blog post, we will explore everything you need to know about rear outlet toilets, including their functionality, benefits, and various types available.

Most toilets found in homes and buildings today feature a floor drain outlet, which partly relies on the force of gravity to efficiently remove waste. This type of is the default choice for most as it requires less pressure for flushing. However, rear outlet toilets are especially needed when there is no floor drain available. This tends to be more common in older cities that might have areas equipped with older plumbing.

Rear Mounted toilets can come in one of two ways: Wall Mounted and Floor Mounted. Wall mounted toilets by their nature need to have a rear drain outlet while Floor Mounted toilets are more of a specialty use case.

In the sections that follow, we will delve deeper into these types of rear outlet toilets and how they operate.

  • Floor Mounted Rear Outlet toilets with a tank
  • Wall Mounted Rear Outlet Toilets with in wall carrier
  • Floor Mounted Rear Outlet Toilets with a Flushometer
  • Wall Mounted Rear Outlet toilets with a Flushometer

What exactly is a Rear Outlet toilet?

Before we dive deep into the types of Rear Outlet toilet. Let’s explain exactly what it is first.

A Rear Outlet Toilet is a type of toilet that has a drain outlet positioned at the back of the toilet bowl, rather than the conventional floor drain outlet found in most toilets. This unique design allows for the waste to drain horizontally through the back wall rather than the floor drain of most bathrooms.

Why use a Rear Outlet Toilet?

There are two reasons why one might need to use a rear outlet toilet

  1. Existing Plumbing calls for a Wall Outlet.
  2. The Building Owner wants to install a Wall hung Toilet

Plumbing Constraints

Most new home construction these days will be properly piped for floor drains on all bathrooms. However, older homes in older cities may not have the proper infrastructure to allow for a floor drain. Especially in older large apartment buildings. Back Outlet toilets were a space saver in this building as they don’t need any extra room below the floor for plumbing pipes. This in turn allows the developer to have more floors on a given height restriction for his new building.

Another common use case for rear outlet is a toilet that gets installed in the basement after the fact. Unless the basement floor was built to accommodate from the beginnings, there will not be any place to pipe the drain. In this instance, the homeowner’s only option is to install a rear outlet toilet with a pump and macerator.

Wall Hung Toilets

A Wall Hung toilet is type of of toilet that is directly mounted on the wall as opposed to the floor. Unlike floor mounted toilet, there is no visible base resting on the floor, and thus nothing to connect to the floor drain. As a result all wall hung toilets have a rear wall outlet.

Wall hung toilets are increasing in popularity due to their space saving nature. They are popular in modern contemporary homes and condos. Therefore, if you’re a minimalist or just a fan of the this type of space saving toilet, your bathroom will need to be plumbed for a back outlet drain.

The 5 types of Rear Outlet Toilet

Now that you understand what a rear outlet toilet is, it’s time to familiarize with the common types of rear outlet toilets that you will see out and about.

Floor Mounted Rear Outlet toilet

If you ever hear a contractor or plumber use the term “Rear Outlet Toilet” without any qualifiers, they are most often talking about a Floor Mounted Rear Outlet Toilet. While we will go through a few more types of back outlet toilet, the rear discharge for those toilets are just a feature. However for the floor mounted back outlet, the back outlet is its identity. It’s meant to simply replace the most popular type of toilet (floor mounted floor outlet toilet) when a floor drain is not available.

The Floor Mounted Back Outlet toilet is constructed the exact same way as you standard residential floor mounted toilet. The major difference is that the trapway redirects the water out to the wall instead of the floor.

Another major difference compared to conventional toilets is that the toilet tank in a back outlet toilet is equipped with a Pressure Assisted tank instead of the typical Flush valve and Fill Valve. This pressurized tank provides additional force to flush out the water since there is no assistance from gravity.

In a standard floor drain toilet, the flush valve opens, allowing water to flow from the tank into the bowl due to the force of gravity. The weight and volume of the water create the necessary pressure to effectively flush away waste. However, in a back outlet toilet where waste needs to be expelled horizontally or at an upward angle, gravity alone may not provide sufficient force for proper waste removal.

Wall Mounted Toilet with in wall carrier

The most common wall mounted toilet for residential applications is the wall hung toilet with an in wall carrier. An in wall carrier is a flushing system that gets installed in the wall. It serves two purposes

  1. It serves as a fill valve and a flush valve to flush the water through the wall hung bowl and fill the tank back up.
  2. It has a built in carrier support for the wall hung toilet. Most residential carrier can hold up to 500 lbs.

Another benefit of the in wall carrier is that it saves space in the bathroom. Since it’s installed in the wall, it makes for a cleaner look and is ideal for small bathrooms.

Tank Type Wall Hung Toilet

A tank type wall Hung toilet is a residential toilet that is wall mounted but still has a toilet tank attached. This is rarely used in this day and age but can come in handy when there is no way for the plumber to install an in wall carrier.

It looks and functions just like a standard floor mounted rear outlet toilet except for the fact that it’s mounted to the wall.

This type of toilet is hard to find. As of the time of this writing, Only American Standard & Proflo manufacture this type of toilet in the US.

Like the floor mounted back outlet toilet, this tank type wall hung toilet is equipped with a pressure assisted valve inside the tank.

Commercial Floor Mounted Rear Outlet Toilets w/ Flushometer

Unlike residential style toilets that are equipped with a toilet tank on top, commercial toilets are most often equipped with a Flushometer. A flushometer is a device that sits on top of a commercial toilet bowl and provide a much more powerful flush than standard toilet tanks. This performance comes at a cost as they are quite noisy, thus not ideal for residential use.

While these devices are way too loud for residential use, they are perfect for commercial use due to the extra pressure provided by the flushometer. This mechanism is perfect for rear outlet toilets, as they need extra pressure to flush properly. As a result, rear outlet toilets tend to be more popular in the commercial sector.

Commercial Wall mount Rear Outlet Toilets w/ Flushometer

Just like their tank-type counterparts, the flushometer-style toilets are available in both a floor-mount and a wall-mount configuration.

The Wall Mount Rear Outlet version operates just like the floor outlet version except for the fact that it’s attached to a wall instead of being bolted to the floor.

For both versions, the Flushometer can be either top mounted or rear mounted. Toilet manufacturers offer both versions as there is enough demand for both in the commercial sector.

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