7 things not to pour down your sink or drain

food scraps in kitchen sink

Danny Baggs

Posted August 16, 2023

It can be tempting to pour any waste liquids down your kitchen sink, or poke leftover bits of food down the drain. But there are some things that should never go down your sink.

Small mistakes can cause big problems. If you’ve suffered numerous sink blockages or pour just about anything down your sink, it’s time to brush up on what not to put down your drains.

RACV Trades plumbers were called out 8,467 times in 2022 to unblock a drain or pipe. “Whatever goes down your drain has to end up somewhere,” said Kieran Davies, RACV’s Head of Home Trades and Services. “You should be mindful of the harm you could do to the environment or your own plumbing.” 
While it may seem tempting to try to fix plumbing issues in your own home, such as blocked toilets, pipes or drains, you could end up doing more damage. Leave serious plumbing issues and blockages to qualified professionals.

Chelsea Smith from The Organising Platform talks about the biggest mistakes you could be making in your kitchen.

Things you shouldn’t put down your sink or drain

1. Oil

Never pour cooking oil down your kitchen sink. It mixes with any debris, creating congealed, greasy sludge that quickly clogs drains – especially because oil is water-resistant. Greases, fats, butter and margarine are no-gos for the same reason. 

“Every time you try to wash down something solid or sticky, you’re running the risk of a blockage and a major headache,” said Davies. 

Simply let these coagulants cool and solidify in a disposable container, then throw them in the bin. You could also use a paper towel to wipe them off your pots and pans before washing.

2. Coffee grounds

Scoop those soggy coffee grounds into your compost bin rather than down the drain. Coffee grounds are one of the most common causes of kitchen sink clogs: they are not totally water-soluble and will stick together when wet. Remember to safely dispose of the grounds in your coffee cup as well as your French press or coffee machine. Coffee grounds can also be reused in the home to help save you money.

coffee grounds in kitchen sink

Coffee grounds can go in your compost bin, but not down the drain. Image: Getty

3. Rice, pasta and noodles

Rice, pasta and noodles all expand in water. If put down your drain, they will continue to swell every time you run the tap until they form a blockage. Pasta is made from flour, so it will also become sticky and catch other debris in your pipes.

4. Medications

Medications shouldn’t block your pipes, but they pose a severe environmental risk when added into water waste. Dissolved medications can cause chemicals to end up in our drinking water, pollute groundwater and soil, and harm livestock and wildlife. “Chemicals in medications and paints can end up polluting natural waterways just like incorrectly disposed litter,” said Davies. Instead of popping them down the sink, take expired and unused medications to your pharmacist to safely dispose of them in medical waste disposal units.

5. Paint

Paint should never be washed down your sink. Whether oil- or water-based, paint contains many toxins and chemicals that should not end up in our water supply. Most councils have rules and regulations that cover how to safely dispose of paints. Otherwise, mix leftover paint with some kitty litter and allow it to dry into a solid before disposing into your rubbish bin.

paint going down drain

Paint can release toxins and harmful chemicals into our water supply if poured down the drain. Image: Getty.

6. Flour

There’s a reason why mixing batter for a cake is hard on your arms: flour mixed with water creates a thick and glue-like slurry. Imagine that same mix down your drains - little wonder then that it can cause blockages. Shake or scrape excess flour on your baking implements into the bin rather than the sink.

7. Fruit and vegetable stickers

Those little stickers you can find on fruits and vegetables are surprisingly harmful to water systems. They are made of plastic and adhesive, so they do not dissolve in water. Instead, they can stick to the insides of your pipes, become caught in wastewater treatment filters, or end up in rivers and oceans where they can be eaten by aquatic wildlife. So, make sure to peel off those stickers into the bin before you wash your produce.


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