Sanitary Tee Vs Wye Pipes: What Are The Major Differences?

Ossiana Tepfenhart
by Ossiana Tepfenhart

Putting together your own plumbing setup is not something an amateur should do. But, some folks still give it a shot and get fairly decent success. Part of their ability to succeed is that they know which fittings to use to distribute their water flow adequately. In order to do this, you will need to know what a sanitary tee is, what a wye is, and how to use each one.

A Wye is shaped like a ‘Y’ and is used to combine two different lines into a single horizontal line which then maintains flow without any clogging problems. On the other hand, a sanitary tee is shaped like a ‘T’ and helps to connect a horizontal pipe to a vertical one.

These two fittings seem incredibly similar in design, and an amateur plumber might think that it’s okay to use one in the place of the other. This isn’t true! Here’s what you need to know about each fitting.

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A Quick Introduction To Sanitary Tees And Wyes

When you first start getting into any type of home improvement, you’re going to need to learn the tools of the trade. With putting together a drainage setup, you’re going to need to get to know what the uses are for each.

What Is A Sanitary Tee?

Sanitary tees are T-shaped fittings that are used in drain setups. A sanitary tee is built to help usher liquids flowing through a horizontal drain into a vertical drain. Since the T shape is great for pushing water downwards while giving the area room for ventilation, most people use it to make drainage easier.

Sanitary tees are great for plumbing because they make it easy for a person to remove clogs by plumbing the area vertically. This makes removing clogs from a vent a cinch.

What Is A Wye?

A wye has a slight bend to it that makes it a lowercase Y, and it’s basically used in the opposite way that sanitary tees are. These drainage fittings bring waste flowing from a vertical drain to a horizontal one. The slight bend makes it possible for the water to go horizontal without a lot of turbulence and reduces the chances of clogging.

Why Can’t Sanitary Tees And Wyes Be Used Interchangeably?

It all has to deal with gravity and the way that the drainage system will work. Using the wrong fitting will cause you to get unnecessary turbulence, which can lead to clogs and unwanted air vacuums. This will cause the system in question to become pretty difficult to maintain, and even more difficult to fix.

A common issue professional plumbers head relates to using wyes or tees in the wrong place. Simply put, repairmen often go out to homes to fix the problem and add the right fitting. Adding the right fitting after everything else was already installed requires a lot more labor and may even require the installation of new piping.

Can You Use A Sanitary Tee Instead Of A Trap?

A P-trap or S-trap is a must in any sink or drain setup. You need to have one, and that means a sanitary tee is not a substitute. In fact, sanitary tees shouldn’t even be on your radar for your setup. There is a good reason why you should never even consider putting a tee instead of a trap.

This is because a sanitary tee is there to direct the flow of waste while keeping vents on. A P-trap (or S-trap) is there to trap sewer gasses inside your drain setup and prevent them from being released into your home. A sanitary tee being used instead would let the sewer gas flow into your bathroom, spread to other rooms, and more.

Oh, and for the record? The same thing would happen if you tried to use a wye instead of a P-trap. No matter how you look at it, you’re going to need to install a P-trap on your drain.

How Much Do Sanitary Tees And Wyes Cost?

The price you pay for a sanitary tee or a wye will depend on the size of the fixture, but regardless of what you choose, you won’t have to worry too much about breaking the bank. Both sanitary tees and wyes cost between $1 to $5 per fixture, making them one of the most affordable parts of PVC piping.

Important Tips And Advice For Installing Sanitary Tees And Wyes

Now that you get the basic differences between tees and wyes, it’s about time that we talk about installation. As we said earlier, we do not advise that you try to install your own plumbing setup. It probably won’t be up to code. But, if you do, then reading over these tips can help you avoid (some) calamity:

  • Always plan ahead of time. This sounds pretty obvious but it’s still worth repeating. Plumbing is not something that you can “wing.”
  • When using sanitary tees, do not attach the vent below to any other lines. This will cause the vent to get clogged with water, and may also cause water locks. In more extreme cases, this can lead to water backing up through the sink.
  • Always make sure that the tees and wyes are secured well. A loose sanitary tee will quickly fall out of place, spraying water everywhere and making a mess. If you have poorly-secured wyes or tees, you will most likely start to see mold, leaks, and significant water damage.
  • If you notice signs of a poorly installed wye or sanitary tee, call a plumber ASAP. An improper install may lead to sink backups, gurgling, and “belching drains.” At times, you may also notice an uptick in clogs or having a hard time having your toilet flush properly.

How Much Does It Cost To Fix An Improperly Attached Sanitary Tee (Or Wye)?

They always say that hiring an amateur plumber is more expensive than hiring a professional. This is going to be the case if you installed a tee or a wye, only to find out you did it wrong. Well, you can’t say I didn’t warn you not to do this. If you have to pay a plumber to fix an improperly attached tee, you will pay an average of $50 to $75 per hour.

How much you’ll spend depends on the extent of the damage. At the very least, you should expect to pay around $100 to $200 for labor alone. This does not include any parts that you have to get for the plumbing, nor does it include repairs for any damage you may have caused to your home via mold.

How Likely Is It That Improper Fittings Will Cause Mold Damage?

Long story short, the answer is very. Because improper fittings are more prone to leaks, clogs, and backups, you will most likely start to see water coming out of places it shouldn’t. What’s worse is that you might not always be able to spot the damage as it happens, which can leave the problem to fester…literally.

It’s not unusual to hear of homeowners who try to do their own plumbing burst into tears when they see sewage flooding their sinks and tubs, or to hear of people having to call specialists from mold that resulted due to water that kept escaping the fittings behind the scenes. This can easily cause thousands of dollars in damage, so do your fittings at your own risk.

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Related Questions

Can you put a 90 in a sewer line?

In most cases, the answer to this question is a hard no. A 90 should never be installed underground unless it’s the base of a vertical plumbing pipe stack. A right-angle makes your line prone to clogs, since hard waste occasionally finds itself in drains. If you need to make a right angle with your piping, use two 45-degree pipe fittings separated by at least 12 inches of PVC piping.

Is it possible to have too much sloping in your drain lines?

Assuming that you are not using special fittings to divert the sewage flow, you can have too much of a slope for your drain line to function. The most your drain line should slope is a scant 1/4 inch per foot. This means that you should only have an inch of drop for every four feet of length that you have.If you have too much of a slope in your drain line, you may start to notice gas bubbles, clogs, or backup. In some cases, it can also lead to turbulence in your system.

Do you really need to vent every drain?

Yes. Every drain needs to have a certain level of airflow in order for water and water to be able to travel through it. Without airflow, your water will become locked in a vacuum seal. This can lead to water being unable to escape the drain, which in turn, will cause massive flooding and backups throughout your home.So, in regards to venting your drain, you will need to have a vent for every drain. Otherwise, you’re in for a big mess.

Ossiana Tepfenhart
Ossiana Tepfenhart

Ossiana Tepfenhart is an expert writer, focusing on interior design and general home tips. Writing is her life, and it's what she does best. Her interests include art and real estate investments.

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