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What not to flush

What you put down your sink or toilet can affect your pipes and our network.

Pouring fat down your drain and flushing wet wipes down your toilet or can lead to some real nastiness, such as fatbergs and overflows.

This doesn't just affect your backyard; blockages can cause problems for your neighbours' properties and the environment too. When sewer pipes are blocked overflows occur, causing untreated wastewater to contaminate our beaches and waterways. These kinds of events are preventable. If we all think before we act, we can help keep our beaches and waterways clean - just how they should be.

Beach showing a view of Rangitoto.

What not to pour down your sink

Whether it's a festive roast or a morning fry-up, you are going to end up with some leftover cooking fat or oil.

Many Aucklanders aren't aware of how to properly dispose of these cooking fats and oils. While small amounts of grease can be left to cool and then wiped with a paper towel, larger amounts of grease require a little more effort. Everything you put down the sink ends up in the wastewater system.

Oil is the glue of a fatberg. Grease and oils poured down your sink slide through your pipes and meet up with other greasy conglomerates and single-use plastic items that have been flushed down the toilet. Over time, these items build up, creating a fatberg.

Image of three fatbergs in pipes.

A nasty combination of fatty acids and unflushable items (wet wipes, tampons, dental floss) create fatbergs that can grow to the size of a bus. Fatbergs can become big enough to clog sewer lines, causing blockages and overflows.

How to dispose of cooking oil, grease, and fat correctly

No matter the season, fats, oils and grease do not belong down the sink. Here's how to dispose of them responsibly or reuse them

Wait for cooking oil to cool. Wait until your used cooking oil has completely cooled before you dispose of it. Hot cooking grease in your rubbish bin is a fire risk. You will need to leave it a few hours to sufficiently cool.

Pour into a non-breakable container with resealable lid. Find a container that will not leak and pour your cooking oil into it. Commonly used containers for disposing of cooking grease are old jars.

Place container in a rubbish bin. Ensure your container of cooking oil is sealed and then place it into your rubbish bin.

Reusing cooking oil. If you do a lot of cooking, you can consider reusing your cooking oil. It's a great way to save on your grocery bills and reduce food waste.

How to reuse cooking oil

Use a cooking oil with a high smoking point. It is important you start off by using a high-quality oil with a high smoking point. The smoking point is the temperature at which oil starts to break down. Do not use olive oil for reuse, as it has a low smoking point. Instead, opt for canola, vegetable, or peanut oils.

Leave used cooking oil to cool. Before pouring your used oil into a container, ensure it has cooled down. Let your oil sit away from a heat source for at least several hours. If leaving your oil overnight, be sure you cover it.

Select a sealable container. To avoid your oil becoming compromised, make sure you used a sealed container. The recommended choice for oil storage is a glass jar.

Filter your oil. Affordable coffee filters can be kept on hand to strain used oil through and into a sealable container. Place a coffee filter (or fine sieve) over your container and pour your oil through. This will remove all undesirable extras like crumbs, batter, and other food particles. Your oil will be ready to go another round!

Store your oil in the refrigerator. Store your used cooking oil in the fridge to extend its shelf life and prevent bacteria growth. Never store used cooking oil in a warm environment as it will cause the oil to break down.

Reuse cooking oil no more than two times. If you've filtered the oil and stored it properly, you can reuse it up to two more times. Check the oil before you use it and dispose of any oil that's cloudy or smells bad.

Fat-busting myths

"If you use dishwashing liquid while pouring the fat, oil, and grease down the sink it will break it up and pass through the pipes."

Using dishwashing liquid to break up the fats and oils left in your pan is only a temporary solution. As the grease moves further down the wastewater network, these oils and fats congeal and cause blockages.

"It's OK to pour grease down the drain if you run hot water with it."

Hot water merely transports the grease further down the sewer line. Eventually the liquid grease will cool and solidify, coating the pipes and forming a blockage.

"It's OK to put fat, oil, and grease down the waste disposal."

Using a garbage disposal only grinds particles down before passing them into the wastewater system. Oil poured down a waste disposal will solidify further down the network and cause build-ups.

What not to flush

There are many things you should never flush down a toilet. Sadly, at Watercare, we pull thousands of these items from our wastewater system every day.


This includes wet wipes, baby wipes, and make-up wipes. Although many wet wipe manufacturers claim their wipes are flushable, wet wipes do not break down like toilet paper and lead to blockages in the wastewater network. Stop wet wipes making their way into our waterways by simply placing a waste bin next to your toilet.


Many people are unsure about proper tampon disposal. Flushing a used tampon may seem like the easiest option but it can have a devastating effect on our wastewater system. Tampons don't break down like toilet paper. Even biodegradable tampons take months to break down, meaning they will remain intact throughout the wastewater network. Tampons must always be disposed of in the rubbish.

Dental floss

By habit, many people flush their dental floss into the toilet once they are done with it. Floss is made of nylon, meaning it will not break down. When flushed through wastewater pipes it becomes entangled in other objects, making blockages larger. Floss has been described as the rope that binds fatbergs together. Even silk or wax floss won't break down in the time it takes to move through the wastewater network. Instead of flushing your dental floss, place it in a waste bin.

Cotton buds (Q-tips)

Though small, cotton buds flushed down the toilet can have a huge impact on the environment. Most cotton buds are made out of plastic. They do not break down in water, but instead attach themselves to fatbergs. Dispose of your cotton buds in the bin.

Pills and prescription medication

Many people are unsure of how to properly dispose of unused or expired pills and medication. You may think you are doing the right thing by flushing them down the toilet, but flushing is not the answer. Instead of flushing, take your expired medication to your pharmacy for safe disposal.


When time comes to dispose of a condom, your brain may not be at its sharpest but this is no excuse to flush it! Condoms are made of latex, a natural product produced from rubber trees, but they still take a long time to break down. Chemicals added to the latex in condoms also prevent them from breaking down quickly. This means condoms get snagged on other items in the wastewater network, causing blockages. Dispose of your condoms in a waste bin.

Nappies and disposable diapers

Even though nappies are labelled disposable, this doesn't mean they should be disposed of down the toilet! Many disposable nappies are made from material that expands when it makes contact with water. Flushing a nappy down the toilet will very likely clog your wastewater pipes. Instead, dispose of used nappies in a bin.