Everyone in the field knows the drill—you show up for what sounds like a simple job only to uncover a DIY disaster, a confusing repair done by someone else, or damage caused by a total accident. Whether it’s a backwards trap, a mystery leak “fixed” with duct tape, or pipes installed like a game of Tetris, you’ve seen it all (and probably fixed it).

BrassCraft, we know plumbers are out there every day solving problems that probably should’ve never happened in the first place. That’s why we’ve pulled together a roundup of the most common plumbing mistakes that end up on your to-do list—along with tips to prevent repeat calls and to make those fixes go smoother.

Here are five plumbing mistakes pros often encounter, and how you and your apprentice can avoid having them come back to haunt you in your next job:

 

Using the Wrong Type of Sealant or Thread Tape

As a pro, you know even the smallest hiccups can create big problems. One example? Using the wrong sealant—or skipping it altogether. PTFE (Teflon) tape is often misapplied or used where pipe dope or a different type of thread sealant would be more appropriate. For example, using standard white thread tape on gas lines or compression fittings is a no-go, yet it still happens. 

How to fix it: Make sure you’re using the correct thread sealant for the material and application: Yellow PTFE tape is commonly used for gas lines, while pink or gray are designed for water. Blue PTFE tape and certain pipe dopes are formulated for use with both gas and water applications, making them versatile options when used correctly. And always wrap in the right direction: clockwise with the threads to avoid unraveling during tightening.

 

Overtightening Supply Lines or Fittings

Over-cranking fittings (especially on supply lines, shut offs or plastic threads) can lead to cracked components, stripped threads or even a fitting that fails under pressure days later. It’s one of those mistakes that can come back to bite you after you’ve left the job.

How to fix it: Hand-tighten fittings first, then follow manufacturer torque specs or give a careful quarter- to half-turn more with a wrench. When in doubt, snug is better than snapped. And make it a habit to inspect components for hairline cracks if anything felt too tight going in.

 

 

Improper Slope on Drain Lines

Getting the slope wrong on horizontal drainpipes is a common issue that causes long-term drainage problems. If it’s too flat, waste doesn’t flow properly; if it’s too steep, water outruns the solids, leaving buildup behind. Both scenarios can lead to clogs or callbacks.

How to fix it: Stick to the standard: a ¼ inch per foot slope for horizontal drain lines per the Uniform Plumbing Code (UPC). Use a level with pitch markings or a slope finder to make sure your slope is accurate. And be sure to double-check after securing hangers or straps to make sure nothing shifted out of alignment.

 

 

Using Compression Water Stops on CPVC Piping

It may seem like a quick fix, but connecting a compression stop directly to a CPVC pipe is something that could lead to major problems. Because CPVC is more brittle than copper or PEX, it isn’t designed to withstand the pressure from compression fittings. This kind of connection could result in leaks or even a full blowout.

How to fix it: When working with CPVC, always make sure you’re using the correct type of stop or transition fitting. Identify CPVC-specific connections or use stops designed for solvent weld applications.

 

 

Not Using Top-Quality Products

Cutting corners on parts is one of the easiest ways to end up right back at the job site. Using low-quality or off-brand components may save some money upfront, but it often leads to leaks, stripped threads, or premature failures that damage your reputation and your schedule.

How to fix it: Stick with trusted, high-quality products that are built to perform and backed by pros. From angle stops to supply lines and everything in between, BrassCraft^® products are designed with durability, reliability, and ease of install in mind. As @district6plumbing says, “Not using top-quality products from BrassCraft” is one of those mistakes you want to avoid-–choosing the right product the first time means fewer callbacks, greater confidence in your work and more trust in your name.

 

Mistakes like these are great teaching moments for apprentices. Keeping an eye on their technique—and explaining the why behind the correction—helps build good habits early on.

Ready to stock up on the products that help you do the job right the first time? Browse our full range of high-quality plumbing products and discover where to buy them—locally or online.