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Top 10 plumbing mistakes made by DIYers

Calling out a plumber can be expensive, especially when it comes to repairing those little jobs like a leaking tap or a non-flushing toilet. But while it may look easy to remove a few pipes or replace a washer, doing it wrong can create more problems later on.

So, in this blog, we are going to look at the top ten plumbing mistakes DIYers make. Avoiding these common mistakes will greatly improve the reliability of your plumbing and reduce the need to call out a professional plumber if things go wrong.

1. Using drain cleaner for sink blockages

Using a drain cleaner to unblock a sink seems like the obvious choice, but doing so may cause more problems than it solves. Drain cleaner is caustic and can easily corrode metal pipes and destroy rubber gaskets if left in the system too long.

The best way to unblock a sink is to use a barbed drain cleaning tool. If this doesn’t work, remove the P-trap and flush out the blockage with water. Drain cleaner should never be used to unblock a sink.

2. Over tightening pipe fittings

When installing pipe fittings, it makes perfect sense to make sure they are nice and tight. But overtightening plastic or metal fittings can cause them to crack, which can result in leaks later on.

When installing fittings, lightly tighten them with a wrench. Don’t apply too much force and avoid cranking down on the handle. Once tight, you should still be able to remove the fitting with light pressure from a wrench.

3. Putting Teflon tape on backwards

Teflon tape, sometimes called PTFE tape, is designed to wrap around threads to prevent leaks. But many DIYers put the tape on backwards so that it unwinds when the thread is tightened.

For best results, wrap the tape three times around the thread in a clockwise direction and make sure you use the right colour tape. Use white or pink tape for water pipes and black tape for gas pipes. You should never use Teflon tape on a flare or compression fittings.

4. Not having the right spare parts

It is common for DIYers to use any spare washers and O-rings they have hanging around when they’re fixing a leaking faucet. However, not using the proper parts will result in more problems later on.

These items are cheap, so don’t risk making the problem worse by installing the wrong parts. Take a trip down to the local hardware store and buy a complete set of washers.

5. Not turning the water off

It’s a rookie mistake and you’ll only make it once, but not turning the water off before replacing a valve or washer is probably one of the most common and damaging mistakes we see.

Make sure you always turn the water off at the mains before making repairs to any pipework, even if it’s just a washer or O-ring. That will save you from flooding the room with water and causing thousands of dollars worth of damage.

6. Using too much force on jammed shut-off valves

Shutoff valves that have not been used for a long time have a habit of seizing. The temptation is to apply pressure to the knob in an attempt to force it open, but this risks breaking the knob and breaking the valve stem.

The valve is seized because the stem seal has fused to the valve stem. If you can’t move the shut-off valve by hand, use an adjustable wrench to loosen the stem nut just enough to break the seal. You should then be able to turn the knob as normal.

7. Sweating copper pipes with water in the line

Sweating refers to the process of soldering two copper pipes together. To create a tight seal, there must be no trace of water in the pipe, because water turns to steam when the blowtorch is applied and that creates tiny pinholes in the weld.

So, make sure the pipe is dry and no water can run down it before sweating. Plumbers used to use white bread to seal pipes, but these days, we prefer to use a special plug to keep the water out.

8. Not using the right tools for the job

Most DIYers attempt to make do with the tools they have at hand, however, not using the right tool for the job makes everything more difficult. A wrong sized wrench can strip a nut and removing a nipple with a pair of pliers can break the pipe.

Plumber’s tools are not expensive, and they are certainly a lot cheaper than trying to fix problems caused by using the wrong equipment, so do yourself a favour and invest in the right tools for the job.

9. Using the wrong drain fittings

Using the wrong drain fitting will not only result in some unpleasant smells, but it could also put you in breach of building regulations. So, you must know the difference between a tee, wye and long or short sweep elbow before fitting them.

Knowing which type of fitting to use is complicated by several factors, including the location of the drain and the directional flow of the water. If you are in any doubt about the correct fitting to use, get in touch with a professional plumber.

10. Installing saddle valves

Saddle valves are used when a low-pressure stream is required. They are often installed for use with appliances such as ice makers or humidifiers, but saddle valves are notorious for leaking, with the leak often going unnoticed for months.

So, it’s best to avoid using saddle valves, even if one was supplied with your appliance. Throw the saddle valve away and use a ball shut-off valve instead. If you already have saddle valves installed, it’s a good idea to replace them before they start leaking.


While there is nothing wrong with attempting plumbing repairs yourself, especially if it is a simple leaking tap or a blocked toilet, you need to be aware that there is a right and wrong way to do things. Doing it incorrectly will only make the problem worse.

If in doubt, don’t hesitate to call a professional plumber. The plumbers at All Day Plumbing are here to help solve your problems both large and small. So, if you need help, give us a call today on 1300 583 587 or complete the contact form here.