11 Common Plumbing Mistakes Homeowners Make (And How to Avoid Them)
Many expensive plumbing repairs start with simple homeowner mistakes. The good news? Most are completely preventable if you know what to look for.
After decades as a plumber, these are the most common mistakes I see—and the easiest ways to avoid costly water damage and unnecessary service calls.
🛠️ Tools & Products Mentioned in This Article
Some of the products below are tools I personally use or recommend as a licensed plumber. If you purchase through these links, I may earn a small commission at no additional cost to you.
1. Forgetting to Replace Washing Machine Hoses
One of the biggest flood risks in any home is an old washing machine supply hose.
Braided stainless steel hoses last much longer than rubber hoses, but they aren't permanent.
A good rule of thumb is to replace them every 10–15 years, even if they appear to be in good condition.
A burst washing machine hose can dump hundreds of gallons of water into your home in a very short period of time.
Pro Tip: Check with your insurance company. Some policies have recommendations—or even requirements—regarding washing machine supply hoses.
How often should washing machine hoses be replaced?
Most rubber washing machine hoses should be replaced every 5–10 years. Stainless steel braided hoses often last longer, but they should still be inspected regularly for signs of wear.
What happens if a washing machine hose bursts?
A burst supply hose can release hundreds of gallons of water in just a few hours, causing major damage to floors, drywall, and personal belongings.
Are braided washing machine hoses worth it?
Yes. Braided stainless steel hoses are generally more durable and resistant to bursting than standard rubber hoses
2. Putting Teflon Tape on Compression Fittings
This is one of the most common DIY mistakes I see.
People wrap Teflon tape around the threads of a compression fitting, thinking it will prevent leaks.
It won't.
Compression fittings seal with the internal rubber or brass gasket, not the threads. The threads simply tighten the fitting together.
Adding Teflon tape is unnecessary and can even interfere with getting the proper compression seal.
Also avoid overtightening. Excessive force can crush or damage the gasket, creating the very leak you're trying to prevent.
Do compression fittings need Teflon tape?
No. Compression fittings seal using the ferrule and compression nut—not the threads. Adding Teflon tape can actually prevent the fitting from sealing correctly.
Why is my compression fitting still leaking?
Leaks are usually caused by a damaged ferrule, scratched pipe, improper alignment, or under-tightening—not because Teflon tape wasn't used.
Can I reuse a compression fitting?
Sometimes, but replacing the ferrule and compression nut usually provides a more reliable seal if the fitting has been disconnected
3. Relying on Drain Cleaner for Copper Pipes
Many chemical drain cleaners claim they are safe for plumbing.
While manufacturers often state they won't harm copper, I still recommend avoiding repeated use.
Chemical cleaners generate heat and expose pipes to harsh chemicals that can contribute to premature wear over time—especially in older plumbing systems.
Instead, try:
Removing the blockage mechanically
Cleaning the trap
Using a drain snake
Addressing the actual cause of the clog
These methods are usually safer and more effective.
Is chemical drain cleaner safe for copper pipes?
Occasional use may not cause immediate damage, but repeated use can contribute to corrosion, especially in older plumbing systems.
What's a safer alternative to chemical drain cleaner?
A plunger, drain snake, or manual cleaning is often more effective and much safer for your plumbing.
When should I call a plumber for a clogged drain?
If the clog keeps returning or multiple drains are affected, it's time to have the drain professionally inspected.
4. Letting Water Flow Into the Toilet Overflow Tube
If water constantly flows into the overflow tube inside your toilet tank, you're wasting water every day.
This often causes what's known as phantom flushing, where the toilet refills periodically even when no one has used it.
Most modern fill valves include an adjustment that allows you to lower the water level.
Proper adjustment saves water and may reduce your utility bill.
Is it normal for water to flow into the overflow tube?
Only briefly while the toilet is refilling. Continuous water flowing into the overflow tube usually means the fill valve needs adjustment or replacement.
Why does my toilet keep running?
A faulty fill valve, worn flapper, or improperly adjusted float are the most common causes.
Does a running toilet waste water?
Yes. A constantly running toilet can waste hundreds of gallons of water every day.
5. Ignoring Sink Drain Build-Up
This is one of the easiest service calls to avoid.
Many slow bathroom sinks aren't actually clogged deep in the drain.
Instead, hair, toothpaste, soap residue and grime build up around the pop-up stopper.
Simply removing the stopper and cleaning it often restores full drainage in just a few minutes.
What causes slow bathroom sink drains?
Hair, toothpaste, soap scum, and shaving residue gradually build up inside the drain pipe.
How can I prevent sink clogs?
Clean the stopper regularly and flush the drain with hot water occasionally to help reduce buildup.
Should I use chemical cleaners for sink buildup?
Not as a first option. Removing the stopper and manually cleaning it is usually faster and more effective.
6. Ignoring Corrosion on Faucet Supply Lines
If you notice corrosion forming on a faucet supply line or shut-off valve, don't ignore it.
Corrosion usually means moisture has been present for some time.
Eventually that small leak can become a major leak—or even burst—causing significant water damage.
Replacing a supply line is inexpensive compared to repairing a flooded cabinet or floor.
Is corrosion on a faucet supply line dangerous?
It can be. Corrosion often indicates moisture, aging materials, or a slow leak that could eventually cause the line to fail.
Should rusty supply lines be replaced?
Yes. Replacing a corroded supply line is inexpensive and can prevent a much larger water damage claim.
What causes supply lines to corrode?
Humidity, minor leaks, age, and mineral deposits are common causes.
7. Using Your Dishwasher Like a Garbage Disposal
Dishwashers are designed to wash dishes—not dispose of food waste.
Always scrape large food particles into the garbage before loading dishes.
Too much food debris can clog filters, pumps and drain hoses, leading to poor cleaning performance and expensive repairs.
Can food scraps damage my dishwasher?
Yes. Large food particles can clog filters, spray arms, drain pumps, and hoses.
Should I rinse dishes before loading the dishwasher?
You don't need to pre-wash them completely, but scraping off large food debris helps your dishwasher perform better.
Why does my dishwasher smell bad?
Food trapped inside the filter or drain system is one of the most common causes.
8. Ignoring Corroded Drain Pipes
Sometimes homeowners see corrosion or staining on a drain pipe but don't notice an active leak.
That's because debris or mineral buildup may temporarily plug the hole.
Unfortunately, the pipe is still deteriorating.
If you see corrosion, green staining or rust on your drain piping, investigate it before it becomes a major leak.
Is rust on drain pipes a problem?
Surface rust isn't always serious, but deep corrosion or pinhole leaks usually mean the pipe is deteriorating.
Can a corroded drain pipe suddenly fail?
Yes. Corroded pipes often leak without much warning once the metal becomes too thin.
How long do cast iron drain pipes last?
Many cast iron drain systems last between 50 and 100 years, depending on water quality and maintenance.
9. Leaving Garden Hoses Connected During Winter
If you live in a cold climate, always disconnect your garden hose before freezing weather arrives.
A frost-free hose bib is designed to shut off inside the house, allowing the remaining water to drain out.
When a hose stays attached, water can't drain properly.
The trapped water can freeze, expand and burst the pipe inside the wall—often resulting in an expensive repair.
Why should I disconnect my garden hose before winter?
Water trapped inside the hose and outdoor faucet can freeze, expand, and crack the pipe inside your home.
What is a frost-free hose bib?
It's an outdoor faucet designed to shut off water inside the heated portion of the house, reducing the risk of freezing.
Can one forgotten hose really burst a pipe?
Yes. It's one of the most common causes of burst exterior plumbing in cold climates.
10. Ignoring Hair in Tub Drains
Before reaching for chemical drain cleaner, remove the hair.
Most slow bathtub drains are simply clogged with hair wrapped around the drain stopper.
Cleaning it out takes only a few minutes and often restores normal drainage immediately.
This is one of the simplest plumbing maintenance tasks homeowners can do.
What's the easiest way to prevent bathtub clogs?
Remove visible hair after each shower and use a drain hair catcher.
Can hair clog a shower drain over time?
Absolutely. Hair combines with soap residue to create stubborn blockages.
Should I use drain cleaner for hair clogs?
Mechanical removal is usually more effective and much safer for your plumbing.
11. Not Knowing Where Your Main Water Shut-Off Is
This may be the most important tip of all.
Every homeowner should know:
Where the main water shut-off valve is located.
How to turn it off.
That everyone in the household knows where it is.
During a plumbing emergency, every minute counts.
Knowing how to shut off the water quickly can prevent thousands of dollars in water damage.
Where is the main water shut-off valve usually located?
Most homes have it where the water service enters the house, often in the basement, utility room, or crawl space.
Should every homeowner know where the shut-off valve is?
Yes. In a plumbing emergency, shutting off the water quickly can save thousands of dollars in damage.
How often should I test my main shut-off valve?
At least once a year. Valves that sit unused for years can become difficult or impossible to operate.
🛠️ Tools & Products Mentioned in This Article
Some of the products below are tools I personally use or recommend as a licensed plumber. If you purchase through these links, I may earn a small commission at no additional cost to you.
Final Thoughts
Most plumbing emergencies don't happen without warning. Small leaks, corrosion, worn-out supply lines and neglected maintenance often give homeowners plenty of notice before they become major problems.
By taking a few minutes to inspect your plumbing and address these common issues early, you can save money, avoid emergency repairs and help protect your home from water damage.
If you're unsure about any of these plumbing issues, it's always better to ask questions or have a professional inspect the problem before it becomes expensive.
Comments