How to Install Toilet Drain Pipes [Easy and Simple Tricks] – Toilet Bazar

After buying the best toilet seat, you have a task to install it and also adjust your toilet drain pipe. Toilet seat for a rental property or home use, you should install its drain pipe properly. In this section, You can learn how to install toilet drain pipes. So let’s start.

What is a toilet drain pipe?

The drain pipe is the portion that transports waste from the bowl to the main drainage system. For better drainage, drain pipes are often made of PVC rather than metal. This component has the most contact with the reservoir and the bowl.

When the handle is pushed, the tank’s water system rushes down into the dish, causing the bowl to drain down the drain pipe, discharging waste out of the toilet and into the sewer lines.

Usually, toilets have a three-inch size, but some reach as high as four and a half inches, based on the kind and amount of outflow. Some toilets even have two-inch sewage pipes, but these are not advised since they hinder drainage and collapse much more easily.

Because a broken or cracked pipe can allow gallons of water to flow into the walls, ground, or ceiling underneath the toilet, causing costly piping and plywood subfloor repairs, these pipes are the most critical and pricey fix in the toilet.

What happens if a sewer pipe breaks?

Water will leak out and contact neighboring objects if a sewage pipe breaks. Mold thrives in damp environments, therefore such surfaces are prone to mold growth. When you notice mold on your roof or walls, you should suspect a damaged drain pipe.

How to Install Toilet Drain Pipes

You can fix the toilet drainage system on your own, but it’s better if you have previous plumbing knowledge because assembly errors can lead to health dangers from sewage gas leakage. If you have any concerns about the procedure, contact a professional plumber.

Contact the local authorities about building rules and permission needs before you begin. Make certain that the drain pipe and vent size meet the requirements of the code. Plan your job to incorporate any inspections that are required.

Locate Toilet and Drain Pipes

Step 1: Determine Access to Pipes

Locate the main sewage stack in your cellar or crawlspace and mark where it ascends through the home and emerges on the roof. Locate the additional massive waste drainage system.

Look for pipes that can be used for ventilation. Consider where you can attach the toilet to the drainage, main stack, and ventilation systems.

Step 2: Plan Location of Pipes

Make a precise strategy for running your toilet sewer pipes. If required, open up walls and delete flooring. Because your toilet has a trap, you may arrange for a straight drainage connection with a few twists as feasible.

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Step 3: Confirm Space for Sanitary Tee

Ensure you have adequate space to attach the sanitary tee to the two basic factors or the combination fitting to a horizontal drain.

Step 4: Check the Building Codes

Examine your building codes to see if there are any restrictions on how lengthy your toilet drainage line may be before discharging and attaching to the stack.

Cut and Assemble Drain Pipes

Step 1: Assemble Pipes Without Gluing

Trimmed the pipes and connect them without gluing to ensure that they are the correct lengths and fit in the designated area. Make sure you have the necessary fittings to connect your pipes to the current drain and vent lines.

Step 2: Check Stack for Adequate Support

Check that your stack or current drain is securely maintained above and below the proposed placement of your interconnection. If required, add supporting braces. Remove a length of pipe based on the length of the hygienic tee or combination connection.

Glue Toilet Drain Pipes

Step 1: Apply Pipe Cleaner and Glue

If there is more flex in the present drain pipes to accommodate the new connection, use a pipe cleaner and then pipe adhesive to the flange and appropriate. Install the fitting and bend it firmly into the flange.

If you are unable to relocate the current stack or drainage pipes, purchase a no-hub adjustable coupling and cut an extra length of the inner tube equal to the coupling’s size. Solder the extra length of pipe into the fitting’s downstream flange.

Step 2: Glue Fitting and Install Coupling

Slide the coupler onto the existing drainage upstairs. Attach the adapter to the downward pipe using glue. Fasten the coupler by sliding it over the joint.

Step 3: Finish Gluing Pieces in Place

Epoxy the remaining tube and attachments into place, finding your way back from the major drainage pipe to the toilet site. Pipe straps are used to secure the pipes every 4 feet.

Ensure the last bend upward beneath the toilet is well-supported and goes sufficiently high for the toilet flange to be installed.

How to Choose A Toilet Vent Or Drain Configuration

Option 1: Indirect Connection

If the toilet outflow is not immediately connected to a vent, you will need to find another means to vent it. If the drainage line is running outward where the vent is desired, use a lowering Y and a 45 ° angle street elbow to direct the vent connection toward the wall. The horizontal exhaust pipe is located just adjacent to the closet curve.

 Option 2: Parallel

Add a 45-degree decreasing Y and a street elbow pointing toward the wall if the vent wall is perpendicular to the drainage pipe. Additional elbow (of any degree) may be required to place the vertical vent wherever you need it.

Option 3: Opposite Side

Use a reduction Y and a street bend if the vent wall is against the sewer line. As desired, the connections can be aimed directly at the wall or at an inclination.

Standard Pipe Sizes for Toilets

Various plumbing pipes transport water to and from your bathroom, yet they are not all the same size. If you intend to install your personal toilet, you must understand what size pipe to use for each piping method. While there is some wiggle room in the size of the tube used for your lavatory, it is always advisable to follow the regulations for seamless construction.

1. Toilet Drain Pipe

The drainage pipe in your toilet transports trash to the major sewer line on your property. Toilet drain pipes are typically 3 inches in diameter, however, drains up to 4 inches in diameter are occasionally utilized. 3-inch pipes are often used to transport water to the toilet, however, a 4-inch pipe may be used to transport wastewater from a residence to a sewer or sewage tank.+

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The drain pipe attaches to the flange that holds the toilet in place, and this flange is typically designed to attach to 3-inch, scheduling 40 toilet drain tubing. PVC drainage pipe is utilized in most residences rather than metal pipe. Plumbers utilize piping-size charts to identify the appropriate pipe size

2. Supply Line to the Toilet

The power grid to the toilet is a normal 1/2-inch copper or polymer pipe that is run from the major water source or a 1/2-inch cooling water connection. This technology is used throughout the residence to power faucets, baths, and any other water-consuming equipment, including the washer.

This 1/2-inch pipe links to the 3/4-inch plumbing fixtures in the house. However, the water system pipe does not go straight to the toilet. The supply line is connected to the tank by a delivery tube.

Toilet Closet Bend

The closet curve is the elbow junction beneath the toilet that links the vertical tank drainage pipe to the descending drainage pipe heading to the main sewer stack of the residence. Because it links the 3-inch drain pipe to the 4-inch drain line, the closet bend has two dimensions.

The peak of the wardrobe bend is made of a 3-inch tube, while the other side is made of a 4-inch piping system. This pipe connection is installed beneath the toilet on the floorboards or the surface.

A multitude of connectors is used to connect metal or plastic pipes. These are intended to link plain pipes, turn curves, split in 2 directions, or link to a fixture.

Drain Line From the Toilet

The drain pipe from the closet bending to the drainage stack has a diameter of 4 inches. In most residences, this is the normal size pipe for toilet drainage, and all major drain stacks are typically made up of 4-inch-diameter tubes. Some properties may have a lower drain pipe size. A lowering link connects the closet bend to the major sewer line.

However, most residences utilize a 4-inch drainage or stack tube. 4 pipes are also implemented to enhance up to 500 fixtures in multi-family dwellings. Bigger drain pipes are only required in big manufacturing buildings, housing developments, or tall places.

FAQ on How to Install Toilet Drain Pipes

Q: Does a toilet drain pipe need a trap?

A: A trap is required on all plumbing fittings. A p-trap has 2-4 inches of stagnant water. This pool of water is known as the trap seal. The trap seal prevents sewage gas from entering your property.

Q: Can a toilet drain pipe go straight down?

A: When the toilet drainage hits a vertical surface, it falls directly between the wall studs. Despite the fact that there is a vertical drop, do not join the pipes using normal 90 ° piping elbows known as “hard 90s.” Clogs might be exacerbated by the sharp edges of these elbow connections.

Q: What happens if a toilet is not vented?

A: Badly vented drain pipes will not adequately transport wastewater and waste products from your building. This might result in overflowing drainage, backed-up toilets, and other plumbing concerns.

Q: Which is better S-trap or P-trap?

A: Most people believe that P-traps are more successful and constant in keeping water trapped than S-traps. Because of their design, they are less prone to drying up and losing their tight seal: a correctly placed P-trap will never break its water seal.

Q: Where should the toilet supply line be placed?

A: Connect a 12-inch copper water pipe to your replacement toilet’s placement. Put the line through the structure’s bottom panel, about 8 inches to the left of the bathroom’s midline. Link this power cord to the sink’s water supply system.


Hopefully, you have a clear idea of how to install toilet drain pipes. But you have to remember that you should use a power saw and slice the Plastic pipe. Before installing the pipes, clear the burrs left by the cutter. In the case of children, never leave power tools unsupervised. Just use PVC cleaner and adhesive only with enough ventilation.

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