Is It Possible To Connect Shower Drain To The Toilet Drain?

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Last Updated on December 6, 2022 by acechapman

The system of pipes connecting to our homes is a mystery for most people. It’s best to leave plumbing problems to professionals, other than simple ones like repairing a toilet or installing new fixtures. But, if you are determined enough to renovate a bathroom or install new fixtures, it is important to consider how the location of your pipes and drainage will affect your plans before making a shower drain to toilet connection a possibility.

Factors To Consider

When it comes to bathroom remodeling, one of the most frequently asked questions is about consolidating the plumbing. Can a toilet and a shower share the same drain? We use one to dispose of waste and the other for cleaning ourselves. We naturally want to ensure that there is no cross-contamination or that the sewage doesn’t back up while we take a shower.

Let’s look at the factors that you should remember when considering whether to join these parts of your plumbing. How can you decide whether your toilet and your shower can share the same drain? What are the best precautions to take before you proceed?

shower drain to toilet connection

Why connect a shower drain to a toilet drain?

Is it possible to have a toilet and shower connected by the same drain? Yes, in a certain way. Although it is not smart to connect them to the same waste trap arm as each other, separate waste pipes can be connected through a process known as wet venting to a common vent. It is important to consider whether this is a good idea. However, there are good reasons to connect the two in most cases.


Every bathroom appliance must be connected to the home’s main sewerage system. You can take each drain line from each fixture and route them to the central sewage outlet. This is more expensive than installing a common vent to connect all fixtures. It is more cost-effective to have your toilet and shower connection attached to the same drain, both from a labor and parts perspective.

Far more practical

It’s not only a matter of financial feasibility but, also convenience. You’ll have to do more planning and execution if you treat each fixture in your bathroom separately from the main sewage outlet. You will need to plan how to work on a shower drain to a toilet connection. In some cases, you may also need to figure out how you will fit PVC tubes in an already congested pipe network. This will reduce the amount of planning and time required to install the toilet and shower lines by connecting them to the mainline with a single vent.

How do you connect the shower and toilet drain?

It’s possible and it’s a good idea, to connect the fixtures to the drainage. But how do you connect them? This is actually a simple process if you are familiar with the pipe network and have access to a few tools. Don’t rush, take your time and make sure you have all the necessary preparations. If you are unsure about the safety of the project’s progress, then it is better to let a plumber do it. Always consult a professional plumber if you aren’t comfortable with the task of removing floorboards and dealing with water systems in your home.

1. Make the necessary preparations.

Here is where you will spend most of your time. You will need to verify the local building codes in your local area before you begin any bathroom renovation. Find specific regulations about the distance between your main waste pipes and the position of your fixtures relative to them.

Materials are also required, including:

  • A pipe saw
  • PVC closet bends in 3-inch sizes (size may vary depending on the local building code).
  • Drain pipes (PVC) 3-inch
  • PVC caps of 3-inch
  • Connectors made of PVC
  • PVC adhesive
  • Shower S-trap

To gain access to your home’s pipe networks, you will need to remove any wall panels or flooring. However, this is not a simple task. You will need to shut your main water valve off before starting the process.

2. Install the common Vent.

Your toilet and shower have a pipe network that is responsible for removing wastewater and other products from your fixtures. The pipe network must be properly designed to prevent water from creating a vacuum within the pipes. To reduce the risks of slow drainage, sewage backup, trapped methane gas, and trapped methane, bathroom systems must have a common vent.

You should connect the vent pipe should to the main vent stack of your network. This usually leads upwards towards the roof. This is where the importance of the common vent lies. Except as stated in local building codes or regulations, the vent must be no more than five feet from the toilet and the shower trap. You will need to add a vent if the distance exceeds 5 feet. Also, ensure the vent is between the fixtures. You cannot connect the toilet’s trap arm directly to the shower. Then link the two to the vent.

3. Connect the shower to the vent.

Your shower trap and piping should be placed higher than your toilet’s in terms of proper positioning. This reduces the possibility of your toilet’s wastewater backing up into your shower. To help water flow, the piping should be laid between the vent and the shower trap at a slight slope. The pipes should be sloping at 1/4 inch per foot from the shower strap.

It is a good idea to connect the PVC pipes to your vent by hand, rather than using a channel lock. This will prevent any cracks or wear off.

4. Connect the vent to your toilet.

Your drainage system should always have the toilet as the last fixture. This is the fixture that you can connect to the waste outlet the most. Building codes often require the pipes to have the largest diameter. It is more practical to connect everything to a toilet drain.

Like the shower, horizontal pipes from the toilet to the vent or main vertical sewage line should have a gradient between 1/4 and 1/2 inches per foot.

5. Check the flow.

After all the pipes are tightened and the adhesive has had time to cure properly, you can turn on your home’s main water supply. To make sure there will be no leaks in your vents or pipes, run the toilet and the shower separately. You will now be able to replace any wall panels or flooring after confirming that there are no leaks.

shower drain to toilet connection

Final Words

Some bathroom projects can be more difficult than others. Although most homeowners can fix a cracked toilet bowl, plumbing repairs require some knowledge and care. Is it possible to have a shower drain to the toilet connection? Yes, but you must prepare well and ensure that all elements are correctly positioned to prevent backups and damage.

Apart from the practicalities of connecting fixtures to the drains, it is important that you have a regular aftercare program. You can keep an eye on standing water in your shower, and you can use a professional plumber snake to clear the pipes and traps of any blockages. This will ensure that you don’t miss any major issues. Pay attention to unusual smells and listen for unusual noises in the drainage. If in doubt, contact a professional plumber.

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