16 Common DIY Plumbing Mistakes

plumber working on pipes with gloves
  • 1-20 hours
  • Intermediate
  • 0-1,000

Basic plumbing repairs or upgrades are often at the top of the homeowner’s DIY list. In truth, many plumbing-related repairs are easily tackled by a mindful home repair enthusiast.

However, it’s also easy to overlook aspects of the job that could cause big issues in the long run.

1. Over Tightening Connections

With the force of water running through, you want to ensure connections are tight in order to avoid leaks. However, it’s easy to have too much of a good thing when it comes to tightening pipe attachments.

Over tightening plastic plumbing pipes can lead to cracks. Those cracks may not show up on the first day but can make an appearance down the road in the form of leaks.

For ceramic fixtures, such as toilets, getting too aggressive with tightening can easily put too much pressure on the ceramic, causing it to fracture.

Even metal pipes can be compromised by overtightening. Use caution when tightening pipe fittings to ensure you don’t strip out the threads, overly compress washers, or break seals or connectors.

2. Under Tightening Connections

Similarly, not getting attachments tight enough can be a big issue when it comes to plumbing installation or repairs.

Some directions say to tighten rings ‘hand tight’. However, that’s a subjective interpretation depending on how strong those hands are. Plumbing connections should be snug.

For most people, that means tightening with your hand and then giving it an extra partial turn with a wrench.

3. Wrapping Plumber’s Tape the Wrong Direction

plumber's tape fixing threads

Plumber’s tape, sometimes referred to as Teflon tape, is a thin, narrow material that helps seal the connection between plumbing attachments.

It’s made to work with the connections, so when they are tightened together, the connectors press the tape into the threads, filling any small gaps where water might otherwise escape.

However, if the tape is wrapped in the wrong direction, it will unravel when the connections are put together.

When applying Teflon tape, hold the fitting with the threads in front of you. Wrap the tape in a clockwise direction. Apply the tape in a steady layer three times around the threads. Then tear off the tape and press the end into the layer before it.

If you wrapped in the right direction, the tacked-down tail at the end should be facing off to the left as you begin installation. If the end of the tape faces to the right, unwrap it and apply it again in the opposite direction.

4. Using the Wrong Type of Plumber’s Tape

There are different types of plumber’s tape specific to each type of material you’re working with. They are specially designed to work with the threads on different types of metal and plastic.

Read the packaging carefully when selecting your tape and match the product to your plumbing situation. Typically a thin white or thick pink thread tape is suitable for fittings that carry water. The tape may also be gray.

If you’re working with a gas line, look for a yellow tape rated for the task.

When working with compression or flare fittings, skip the tape altogether.

5. Using Liquid Drain Cleaner

liquid drain cleaner

It’s great when you can go to the store, make a small purchase, bring it home for use, and solve the problem. When it comes to clogged drains, commercial drain cleaners are rarely the best solution, however.

Liquid drain cleaners are harsh chemicals that actually damage plumbing fixtures as they travel through the system. They can eat away at pipes and erode rubber gaskets, both of which lead to leaks.

Commercial drain cleaners that come into contact with fixtures can also eat away the protective layer on porcelain or stainless steel.

If a drain cleaner fails to remove the clog, it will remain lodged in the pipes. When you remove the trap or other plumbing connection, you have to deal with those toxic chemicals as they pour out.

A better solution is to start with an appropriate drain snake, also known as an auger. This tool does a better job of clearing the drain without the chemical component.

6. Failing to Properly Prepare for the Repair

Most plumbing jobs aren’t particularly difficult. However, they can be frustrating. Broken handles, cracked connections, and ubiquitous clogs are just part of the fun.

In addition to the primary pipes and connectors, there are several smaller components to the plumbing system.

When making repairs, always over-prepare by picking up extra washers, gaskets, supply lines, O-rings, faucet stems, cartridges, and other essential parts.

Take measurements before you head to the store, or take the old part with you. While plumbing fixtures are fairly standardized, getting the wrong diameter pipe or hose means additional trips for more supplies.

Make sure you have the right tools for the job too. Some plumbing jobs require a plumber’s wrench, for example. Don’t assume your basic tool kit will work or the job will take longer than anticipated.

Being without a toilet in a single-bathroom home is a significant inconvenience, as is doing without a functional kitchen sink. Do your best to minimize the repair time by having everything you need before getting started.

7. Flooding Caused by Failure to Properly Turn off Water

Water will run out of any available opening, especially water under pressure. Don’t think you can make a quick plumbing repair without turning water off at the source. It just doesn’t work and can result in a major mess and even water damage.

8. Strong Arming the Shutoff Valve

plumber tightening pipe

There are a few different ways to shut off the water when beginning a plumbing project. The type and location of the project make a difference. The setup of your home is another factor.

When working on a toilet, there is typically a local shut-off near the base of the toilet. Most sinks also have a shut-off valve beneath them near the ground. Some sinks have separate shut-offs for hot and cold water lines.

For house-wide projects or when your home isn’t equipped with local shut-offs, you’ll need to turn the water off at the main, which is typically located near the street or water meter.

When turning shut-off faucets off inside the home, use patience. It’s common for them to become stuck when not in use. Getting overly aggressive with your technique will result in a broken faucet knob.

If you can’t loosen the knob, grab a wrench and loosen the nut behind the faucet knob. This breaks the seal, allowing the knob to turn once again.

9. Not Knowing How Things Go Back Together

plumbing parts on a tile floor

Often, the eagerness to dig into a project overrides planning for the steps down the road. Whatever you take apart while working on DIY plumbing tasks around your home, you’ll need to put it back together following the repair.

Issues commonly occur at this point when memory fails about how to put the components back together in the right way.

Do yourself a favor and take pictures before you begin dismantling anything. You can then use them for reference if you get hung up later on.

10. Mixing Pipe Materials

Metal works well with metal, and PVC matches nicely with other PVC. However, this is not the time to mix and match materials, even different types of metal with each other.

Make sure you are familiar with the parts you need, including size, for a seamless and long-lasting repair. Avoid even making a temporary fix with the wrong materials.

It’s too high a price to pay when drips and floods cost you more time, money, and inconvenience.

11. Damaging the Fixture’s Finish

Like all products, fixtures for bathrooms, kitchens, and laundry rooms come in a variety of quality ranges. This includes the finishes on the surface of faucets and other components.

Some are quite easy to damage with scrapes or even peeling surface materials.

When a task seems like a simple fix with a wrench, make sure to protect the surface with a cloth or use specific plumbing tools made to do the job without scratching or crushing your fixtures.

12. Skipping Permits

While not all household plumbing jobs require permits, many do, especially if you’re working on a remodel or renovation.

Obtaining these permits might be more exhaustive than you think. Sometimes it requires blueprints, approval from an engineer or other professional, and a detailed outline of the specific aspects of the project.

For basic DIY home plumbing projects, however, it’s best to check in with the planning department so they can tell you whether it’s something that actually needs a permit at all.

If you do, it may require an inspection at some point in the process—maybe more than one.

The purpose of permits is to ensure the safety of the project, so work with your city’s planning department for your own sake.

They will evaluate the project for proper supplies, layout, water runoff, and other features that could save you from cleaning up a flood later on.

While verifying the steps you take are up to code is time-consuming and inconvenient, it can save you from having to redo the work in the future.

Permits are one of those things everyone hates. It’s just a way for the county to take your money, right? No. Inspections and permits ensure everyone’s safety, from the current homeowners to renters and future owners.

It also protects the neighbors and contractors on the job. Depending on where you live, permitting can be a major pain, so it’s tempting to postpone or skip them altogether.

The truth is, though, the majority of the time, it will come out at some point in the future if you try to skirt the process.

It will likely cost you in one of two ways. Either you will be fined for not following the rules, or the inspector will make you tear out completed work until the permitted portion can be inspected and improved.

Sometimes both penalties are implemented.

13. Calculating an Improper Slope

Water runs downhill. In fact, many plumbing functions rely on gravity. That means if you fail to provide a slope for runoff, stagnant water will become your nemesis.

This is true in the shower, on the patio, when configuring downspout runoff, around the sump pump, and anywhere else you’re dealing with the drainage or movement of water.

14. Improperly Locating Fixtures

This goes back to local codes, but also convenience. If you’re starting from scratch, tackling a renovation, or remodeling an older home, failing to properly locate fixtures can come with frustrating and problematic results.

For example, the toilet should be located 15-18” from front and side walls. Replacing a round toilet with an elongated one can mean blocking door closure or pressing your knees up to a wall.

Also, when replacing previous fixtures, you may find the new fixture doesn’t line up or sit the same way.

15. Failing to Winterize

frozen pipes

This is a very common household plumbing problem. If you live in a cold climate, protecting your pipes is essential.

If water is allowed to freeze inside the pipes, it expands, busting out anywhere it can along the plumbing lines. This can damage irrigation systems, flood the basement, or burst a pipe behind a wall in your home.

Before cold weather strikes, drain water from any lines you aren’t using. Purge the irrigation system. Also leave faucets turned on enough for a slight stream of water to run through.

Although wasteful, this keeps the water moving so it doesn’t become stagnant and freeze in place. Open cupboards beneath cabinets to allow warm air to circulate around the pipes. Also place insulating caps on outdoor faucets.

16. Putting Things Down the Drain

Your drains work hard to take waste away from your home. Like the arteries that take essential oxygen, blood, and nutrients to your heart, your home’s pipes need to remain clean for proper flow.

Avoid putting grease down the drain, which turns into fat solids along the way. Abide by the recommendation to never flush any material besides human waste and toilet paper down the toilet too.

Even if a product says it’s flushable, such as wipes, place them in the trash instead.

Managing your own plumbing issues is an effective way to further develop your DIY skill set and save some money. With each project, consider the time estimate, whether you’ll need permits, and if you have the skills required for the task.

In the meantime, continue learning by evaluating these 9 Plumbing Trends. Also check out How to Prevent Plumbing Emergencies and take a look at these Plumbing Tips and Tricks.