Common Plumbing Mistakes: Misusing Fittings like Wyes and Tees

Plumbing projects can go wrong fast when fittings like wyes and tees are misused. Whether you're a seasoned pro or a DIY enthusiast tackling your first project, knowing how to properly install these fittings can save you from leaks, slow drainage, and costly repairs. Let's break down some of the most common plumbing mistakes and how to avoid them.

Your Handy Plumbing Fittings Guide

Mistake #1: Using the Wrong Fitting for the Application: Sanitary tees are designed for vertical-to-horizontal transitions and venting, not for drainage. Using it to connect horizontal drain lines can lead to poor drainage and clogging because the sharp transition disrupts the flow of waste. Wyes are designed for smoother transitions in drainage systems. However, using them incorrectly, such as in venting applications, can lead to issues like siphoning water out of traps, allowing sewer gas to escape.

Solution: When in doubt, a wye is the better option for horizontal drainage connections, as they allow for a smoother, more efficient flow. If you need venting or to connect a horizontal branch pipe to a vertical drain pipe, opt for a sanitary tee.

For more information, we recommend this video: Where to use wyes, tees, and different types of elbows.

Mistake #2: Installing Wyes in the Wrong Direction: A wye fitting is only effective when installed correctly. Positioned incorrectly, wastewater will have to fight gravity or take an awkward turn – causing blockages and slow-moving drains.

Solution: The branch of a wye should always angle downward at 45 degrees (or be properly vented) to maintain optimal flow.

Mistake #3: Using a Tee Instead of a Wye for Horizontal Drains: Tees are great for venting, but using them in horizontal drain applications can create turbulence in wastewater flow, leading to backups and poor drainage.

Solution: Stick to wyes for horizontal drains to keep things moving smoothly.

Mistake #4: Forgetting to Vent Properly: Even if you use the right fittings, improper venting can throw your whole system off balance, causing siphoning and gurgling drains. Without a vent, your system won’t drain efficiently and may even allow sewer gases to enter your home — yikes!

Solution: Always ensure that your system has proper venting to maintain good drainage and prevent unpleasant odors.

Mistake #5: Choosing Low-Quality Fittings: Not all plumbing fittings are created equal. Cutting corners with low-quality materials can lead to weak connections, leaks, and frequent failures.

Solution: Investing in high-quality fittings, like those available at SquarePeg, gives you a secure, long-lasting plumbing system. Brands like Charlotte Pipe, Sioux Chief, and Zurn are trusted for their durability and reliability.

Mistake #6: Skipping Proper Seals and Connections: Even if you’ve got the right fitting, failing to properly seal and connect it can cause leaks down the road.

Solution: Always use the correct type of pipe cement, primer, or pipe thread sealant for your materials. And don’t forget to check for a snug, secure fit — loose connections are a recipe for disaster.

Mistake #7: Ignoring Local Plumbing Codes: Plumbing codes exist for a reason, and ignoring them can result in failed inspections, costly fines, and dangerous plumbing issues.

Solution: Before starting a project, check your local building codes to make sure you’re using the correct fittings in the right configurations. This is especially important for wyes and tees in drain-waste-vent (DWV) systems.

For more common mistakes, check out this blog:  The 10 Most Common Plumbing Mistakes DIYers Make.

Get It Right the First Time

Plumbing mistakes can be frustrating and expensive, but with the right knowledge and quality parts, you can avoid the common pitfalls. At SquarePeg, we stock top-tier plumbing fittings and supplies to help you avoid common plumbing mistakes to get the job done right. Whether you're a pro or a DIYer, trust us to have the best products for your project.

Got questions about which fittings to use? Reach out to our team or browse our selection online. Let’s keep your plumbing flowing smoothly!