Sanitary Tee Vs. Wye: Picking The Correct One

At first glance, sanitary tees and WYEs look almost identical. They both feature a section branching from the main portion of the fitting. They both have a place in plumbing, but each fitting has a slightly different application.

Key Points:

  • Sanitary tees and sanitary wyes are plumbing fixtures shaped in the letter ‘T’ or ‘Y,’ respectively.
  • The shape of the two fittings affects their installation difficulty, space requirements, and flow type.
  • Sanitary tees are used for connecting horizontal lines to vertical lines, while WYEs are used for combining two pipes into one, creating a single flow in one horizontal direction.

So, what are the main differences between a sanitary tee and a sanitary wye? Let’s find out.

What Is A Sanitary Tee?

NIBCO - K09825CA C4811 2 HXHXH SANITARY TEE PVC, White, 2 Inch (C48112)

A sanitary tee is exactly what it sounds like: a sanitary plumbing fitting shaped like the letter ‘T.’ The fitting features three open ends, with the branched portion extending off the main portion to form a ‘T.’ The branched portion of the fitting curves away from the main body of the fitting, making them ideal for connecting horizontal drains to vertical drains.

With a sanitary tee, liquid easily passes through the tee into the vertical drain, as the curved branch constantly leaves room for air to pass through. This ensures the liquid flow remains laminar and avoids stoppages due to a lack of airflow.

Sanitary tees are available in a variety of materials, including PVC, stainless steel, ductile iron, and carbon steel. You can find varying types, including straight and reduced tees, in numerous docking forms.

What Is A Sanitary Wye?

NIBCO U4810 11/2 HXHXH 45 WYE PVC White, 1.5 Inch

Like the sanitary tee, the sanitary wye gets its name from its shape. As the name implies, the sanitary wye features the shape of a lowercase ‘Y,’ with a branch angling off the main portion of the fitting.

These fittings feature three openings, with the branched opening situated at a 45-degree angle. The bend is slight, making these fittings ideal for scenarios where a sanitary tee wouldn’t work. For example, they’re often used to connect vertical lines to horizontal lines, as a tee isn’t a suitable fit.

However, they’re also suitable for combining two pipes into one, creating a single flow in one horizontal direction. The design facilitates the constant flow of liquids through the lines without clogs or blockages.

Sanitary wyes, like sanitary tees, are available in numerous materials, including PVC, copper, stainless steel, and carbon steel.

Is There A Difference Between Sanitary Tees And Wyes?

The key differences between a sanitary tee and a sanitary wye are the usage and shape. However, while this difference might seem minor, it affects various aspects, including applications, cost, and more. The chart below outlines the primary differences between the two for easy comparison:

FactorSanitary TeeSanitary Wye
ShapeT ShapeY shape
FlowLaminar flowPositively directed
PriceInexpensiveMore expensive
Space necessaryMoreLess
Branch angle90 degrees45 degrees
ApplicationsHorizontal to verticalVertical to horizontal; two lines into one horizontal
Installation DifficultyEasyDifficult
Material typesPVC, stainless steel, cover, ductile iron, carbon steelPVC, copper, stainless steel, carbon steel, ductile iron


The shape of each fitting serves as one of the key differences between the two. While the sanitary tee features a 90-degree bend to its branched opening, the sanitary wye boasts a gentler 45-degree angle toward its branched opening.

The shape of each fitting affects various aspects, such as the installation difficulty, space required, and flow type. Generally speaking, sanitary tees are easier to install than wyes, although this may vary based on the particular installation application.

In addition, the design of the tee usually requires more space than the wye, although space requirements only differ slightly. The shape also affects the flow of liquids moving through, as the wye fittings may have restriction points while the sanitary tee doesn’t.


The application of each fitting is arguably the most important difference between the two. The sanitary tee is intended for connecting horizontal lines to vertical lines, while the wye fitting is designed to join vertical lines to horizontal lines.

While the application is only flipped, choosing the correct fitting is critical for proper function within the drainage system. If you choose the wrong fitting for the job, the drainage system may not function properly, leading to blockages and drainage issues within the plumbing network.

For example, if you use a sanitary wye when connecting a horizontal line to a vertical line, the setup will effectively restrict vent air. Since proper airflow through the pipes is essential for drainage, as a vacuum will form without it, a sanitary tee is necessary for this application. The tee features a gentle curve instead of a harsh angle, allowing air to remain in the system and promoting proper airflow.

Or, let’s say you’re joining a vertical pipe to a horizontal line. If you chose a sanitary tee, liquid from the vertical pipe would flow directly down into the horizontal pipe, as the soft bend isn’t enough to redirect the flow in the correct direction. This leads to backflow issues, so a sanitary wye is necessary. The angle of the wye redirects water from the vertical pipe in the proper direction, which helps avoid backflow issues.

Since tackling plumbing problems is the last thing most homeowners want to deal with, it’s important to choose the right fitting based on the application.

While sanitary tees and WYEs are fittings used to connect and redirect pipes, they do not serve the same purpose as a trap in plumbing. Sanitary tees and WYEs are fittings used to change the direction or flow of pipes, while traps are designed specifically to prevent sewer gas from entering the building.

Frequently Asked Questions (FAQs)

Can You Use Sanitary Tees And Wyes Interchangeably?

Sanitary tees and wyes have entirely different applications, so you can’t use them interchangeably. The design and shape of each fitting make each suitable for something different. If you use the wrong fitting for your plumbing project, you may encounter various issues, such as flow restrictions or backflow problems.

If you’re unsure which fitting to use for your plumbing project, consult a local plumber for assistance. It’s better to double-check before installing the fitting than deal with the headache of fixing it later!

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