Think before your flush: 8 things not to flush down the drain

Date published 13 Aug 2019, updated 13 Jan 2025

Have you ever heard of a fatberg? These sewer blocking masses of congealed fat, wet wipes and food waste are becoming a serious problem for Australia’s waste water treatment plants, and they are costing the government millions to remove them.

In 2018 Queensland Urban Utilities reported that it removed 360 fatbergs from the sewers over 12 months, that’s nearly one a day! And in Sydney’s Malabar Water Treatment Facility they have been removing about six tonnes of wipes in the plant each day, along with all sorts of other 'non-flushables'.

You might think these fatbergs can only be found deep underground in the sewers, but really they can form in any drainage pipe - including the ones in your property. So to help you avoid a nasty blocked pipe or clogged up drain, here is our guide on what not to flush down the toilet!

What not to pour down the sink

Think again before you pour these down the drain or wash them down the kitchen sink:

Cooking oils, grease and fats

When you pour hot oils and grease down the drain they cool quickly and congeal in the pipes. They mix with the other ‘non-flushables’ and create a solid mass in the sewers. So when it comes to disposing of cooking oil and fat, here’s what you should do instead:

• Wait until the fat has cooled and scrape into the bin
• Wipe greasy pans before washing to get off the excess
• Save excess oil in a container and contact your local council to find out how to recycle it

Food scraps

Along with cooking oil, keep other foods and kitchen scraps out of the drain. Seeds, eggshells, pasta, they can all cause blockages and clog your pipes as well as the sewer.

The biggest culprits that find their way down the sink are coffee grounds and tea leaves, which along with your other fruit and veg scraps can all go in the bin, or better, the compost! You could also use a sink strainer over the plughole, to make sure you catch even the smallest scraps.

Paints, Bleach and strong chemicals

All of these products have chemicals and toxins in them which can’t always be removed in water treatment plants, contaminating the environment and sometimes even our drinking water. There is also a risk that some chemicals might combine in the sewer and cause a dangerous reaction in the pipes. If bleach goes down the drain and mixes with a substance that contains ammonia, like glass cleaner, they can create a deadly toxic gas.

Always read the label to find out how to safely dispose of your chemical cleaning products. And speak to your local authority about how to get rid of leftover paint - although you could consider donating it to a local arts or theatre school?

What not to flush down the toilet

Other than toilet paper, nothing else should be flushed down the toilet. All of these things belong in the bathroom bin, and not the bowl:

Wet Wipes

Wet wipes are one of the main ingredients in a fatberg. They don’t break down in the sewer the same way toilet paper does, they get glued together by the congealing oils and fats in the drain and cause a bigger blockage.

Whether they are marked as flushable or not, the advice from experts is to never flush any form of wipe down the toilets. That includes cosmetic wipes and cleaning wipes too.

Nappies and Hygiene Products

Just like wet wipes, none of these will break down in the sewer, because they are all made to soak up liquid and expand. Once these get into the system they’ll cause major pipe blockages, and if this happens in your pipes, you or your neighbour might discover a nasty septic leak to clean up.

All of these items and their packaging belong in the bin. If you don’t have one in your bathroom, consider bringing one in to help promote your household throwing it away and not flushing it.

Contact Lenses

Contact lenses don’t necessarily cause blockages, but when they break down into smaller pieces they get through the water processing system and end up in our oceans and waterways. Contact lenses have been listed as a key contributor to microplastic pollution in the ocean, and have even been found inside our seafood. So unless you want to see them back on your plate, think twice before you flush them down the drain.

Hair and Dental Floss

Can you flush hair down the toilet? The short answer is no, you really shouldn’t. Anything that can tangle needs to go in the bin. Hair and dental floss can both wrap around other objects in the drain and cause bigger blockages. Dental floss is especially harmful as it’s made from nylon and doesn’t break down. Look out for eco-friendly biodegradable dental floss. Your hair can also be used to fertilise plants. Collect your loose strands and mix them with the soil around your pot plants or flower beds.

Medicines and pharmaceuticals

You might have seen it done in movies, but you should never flush pills or tablets down the toilet. Water processing plants can’t always filter the medicinal contents out and so they stay in the water and contaminate rivers and waterways. This can not only harms the plants and wildlife, but it also means they can find their way back into our drinking water.

Ask your local pharmacist or chemist about the best way to dispose of old medicines.

Environmental impact of flushing non-flushables

Flushing wipes or paper towels down the toilet not only leads to blocked pipes but also poses serious environmental risks. Here are just some of the environmental impacts of flushing items not meant to be flushed:

1. They pollute our waterways

One of the biggest issues about wet wipes is that they are often advertised as being biodegradable. This may be true, however, the process can take months – and even years to decompose. What happens in the meantime is that they can accumulate in our waterways including rivers, lakes, and oceans. This can cause harmful algal blooms and litter coastlines, threatening not only marine life but birds and other wildlife. 

2. They harm our marine life

Non-flushables that find their way into waterways can be mistaken as food by marine animals. They may also trap and entangle sea life including turtles and jellyfish, and disrupt marine habitats. 

3. They can end up in our food

When non-flushables like wet wipes break down, they can fragment into microplastics, which are ingested by marine creatures such as zooplankton; a common food source for fish. As these microplastics are ingested by larger fish, we humans end up eating the very plastics we dispose of down our toilets. 

4. They disrupt the ecosystem 

The accumulation of wet wipes and other non-flushable debris in waterways disrupts marine habitats like coral reefs and seagrasses. When waste such as wipes smother reef beds, they hinder photosynthesis – a crucial process required for the health and growth of marine plants. As coral reefs and sea plants decline, the biodiversity within these ecosystems is threatened, resulting in the loss of marine species. 

Waste disposal alternatives

With all these items to avoid flushing, it’s essential to know how to dispose of waste alternatives responsibly. Here are a list of safe waste disposal methods:

1. Wet wipes, sanitary items, nappies

• Rubbish bin: Always dispose of wet wipes and other non-flushable items in your general waste bin. Keep a small rubbish bin in your bathroom to make this easy.

2. Hair and dental floss

• Rubbish bin: Both hair and dental floss should be disposed of in your general waste bin. 

3. Cooking fats and oils

• Solidify and put in the bin: After cooking, let the oil/fat cool and solidify in the pan, then place it in some paper towel or container and throw it in your waste bin.
• Recycle: Some recycling centres accept used cooking oil to convert into biodiesel. Collect your cooking oil and put it in a container to drop off at your local recycler that accepts oil. 
• Compost: Small amounts of vegetable oil can be added to your compost heap. 

4. Medications

• Return to your pharmacy: You can take any unused or expired medications to your local pharmacy where they will safely dispose of them. 
• Rubbish bin: After checking if it is safe to do so,  you can throw your unused or expired medication into your general waste bin. 

5. Food waste

• Compost: Food items like vegetable scraps, fruit, coffee grounds, and egg shells can be composted in your backyard.
• Rubbish bin: For foods that can’t be composted (like dairy and meats), dispose of them in the trash. 

Home remedies for drain maintenance

If you’re wondering how to prevent clogged drains, consider using home remedies that are both effective and eco-friendly. Here are some remedies to incorporate into your drainage pipe maintenance to prevent nasty clogs:

Baking soda and vinegar drain cleaner

Pour half a cup of baking soda down the drain followed by half a cup of regular white vinegar. Cover the drain and let the mixture fizz for up to 30 minutes. Finish by pouring about 1 litre of hot or boiling water down the drain. This will break up any debris in your pipes and dissolve grease and minor blockages. 

Boiling water and baking soda

Pour a mixture of boiling water and baking soda down the drain to maintain your pipes and keep foul odours at bay. 

DIY solutions for minor blockages

When it comes to drain blockages prevention or addressing minor clogs, there are a couple of tried and true plumbing maintenance tips that can help below, but if in doubt always call a plumber: 

Use a plunger

Opt for a sink or toilet plunger to dislodge any minor blockages. Firmly cover the drain pipe to create a seal, then vigorously plunge up and down to restore proper flow. 

Plumbing snake or wire hanger

If plunging fails to dislodge the clog, get a plumbing snake or a straightened wire hanger to physically break it up. Insert into the drain and carefully manoeuvre it until all debris is extracted. Flush afterwards. Repeat if needed.