We all know the golden rules of kitchen plumbing: don’t pour oil down the sink, and never flush wet wipes.
But what if we told you there’s another everyday culprit quietly wreaking havoc on your pipes—and chances are, you’re guilty of it?
It’s not just the usual suspects
Let’s be honest, most of us have been well-schooled in the dangers of pouring cooking oil or bacon grease down the drain.
We’ve seen the horror stories of ‘fatbergs’—those monstrous, congealed blobs of fat and rubbish that block up sewers and cost councils millions to remove.
And as for wet wipes, well, they’re practically public enemy number one in the world of plumbing. But there’s a sneaky, lesser-known offender that’s probably slipped under your radar: milk.
Yes, you read that right. Milk.
The surprising truth about milk and your drains
Sydney Water recently took to social media to issue a public service announcement that’s left Australians scratching their heads.
In a light-hearted video, they reminded us not to pour oil down the sink (tick, we knew that), but then dropped the bombshell: ‘And don’t pour milk.’
Cue collective confusion. The comments section exploded with questions: ‘WHERE DOES THE MILK GO?’ ‘What am I meant to do with half a jug of milk?’ ‘Wait, why not milk???’
It turns out, this isn’t just a quirky suggestion. According to Ben Armstrong, Sydney Water’s Principal Manager Environment, a whopping 70 per cent of Sydneysiders think it’s perfectly fine to pour leftover milk down the sink. But here’s the catch: it’s not.
Why is milk a problem?
You might be thinking, ‘But milk is just a liquid—how bad can it be?’ The answer is, surprisingly bad.
When milk (and other dairy products) enter your pipes, they can contribute to blockages in a couple of ways.
First, milk contains fats and proteins that, when combined with other substances in your wastewater system (like oil, grease, and even those sneaky wet wipes), can solidify and form stubborn clogs.
Credit: Sydney Water / TikTok
These clogs, known as ‘fatbergs’, can block pipes, cause wastewater to back up, and even lead to overflows into homes, gardens, and local waterways.
Not only is this a costly headache for homeowners, but it’s also a major environmental hazard.
Second, milk is high in nutrients like nitrogen and phosphorus. When large amounts of milk enter the sewer system, it can disrupt the delicate balance of bacteria that treat wastewater.
This can lead to reduced water quality and environmental damage if untreated or poorly treated water is released into rivers and oceans.
What should you do with leftover milk?
So, if you can’t pour it down the sink, what’s the alternative? Armstrong has a simple solution: give your garden a treat!
Dilute leftover milk with water and use it to water your plants. Not only does this prevent plumbing problems, but milk is actually a great source of nutrients for your garden. Your roses and tomatoes will thank you.
If you have a compost bin, small amounts of milk can also be added there, but be careful—too much dairy can make your compost smelly and attract pests. For larger quantities, check with your local council for safe disposal options.
Credit: Sydney Water / TikTok
Other surprising items to keep out of your pipes
While we’re on the topic, here are a few more everyday items you should never pour down the sink or flush down the loo:
- Coffee grounds: They clump together and can cause blockages.
- Rice and pasta: They swell with water and can clog pipes.
- Eggshells: The membrane can wrap around other debris and create a net-like blockage.
- Paint, chemicals, and medication: These can pollute waterways and harm wildlife.
A little prevention goes a long way
It’s easy to think that a splash of milk or a spoonful of coffee grounds won’t do any harm, but over time, these small actions can add up to big problems.
By being mindful of what goes down your drains, you’ll save yourself from costly plumbing bills and help protect the environment.
Have you ever had a plumbing disaster caused by something unexpected? Or do you have a clever tip for disposing of kitchen waste? We’d love to hear your stories and solutions in the comments below! Let’s help each other keep our pipes—and our planet—in tip-top shape.
Also read: Is your kitchen really clean? Nine spots you might be missing
