What Can Go Down Your Sink? (And What Absolutely Shouldn’t)
Let’s face it — most of us have poured something questionable down the kitchen sink at least once. Whether it’s leftover coffee, pasta water, or the last bit of gravy from Sunday lunch, it’s easy to assume the drain will just take care of it. Out of sight, out of mind, right?
But here’s the deal: your sink isn’t a magic hole that makes stuff disappear. I’ve been elbows-deep in blocked pipes enough times (yes, real rubber gloves and all) to tell you — what you pour down the drain matters. Big time. Clogs, bad smells, even damage to the environment can all start with one innocent pour.
So let’s break it down — what can go down the sink safely? And what should go absolutely nowhere near it?
The Short Answer: Not Much
Here’s the rule of thumb I always tell clients: if it’s not plain water or a small amount of a fully water-soluble liquid, don’t pour it down the sink. Simple as that.
Most plumbing systems, even modern ones, aren’t built to cope with anything that sticks, clumps, expands, or hardens. And your kitchen sink is connected to pipes that, over time, can clog with just a thin lining of grease or food debris.
What Can Go Down the Sink?
Let’s start with the safe stuff:
- Cold water and hot water — Obviously.
- Mild soapy water — From dishwashing, as long as it’s in small quantities.
- Diluted liquids — A splash of juice or diluted vinegar while cleaning won’t hurt.
- Tiny food particles — The stuff that slips through after you scrape your plate into the bin. But even then, a sink strainer is your best mate.
What Should NEVER Go Down Your Sink (And Why)
1. Cooking Oil, Fats, and Grease
Bacon grease, melted butter, meat drippings — they’re liquid when hot but solid when cool. And once they harden inside your pipes? You’ve got a slow drain at best and a full-on fatberg at worst.
Instead: Pour it into a container, let it solidify, then chuck it in the bin.
2. Pasta, Rice, and Noodles
These expand in water. Even if they’re cut up or chewed bits, they can swell and cling together inside your pipes. I once pulled out a clog that looked like someone had dumped an entire spaghetti dinner down there.
Instead: Scrape leftovers into the bin or compost. Don’t rinse them into the drain.
3. Coffee Grounds and Tea Leaves
You’d think they’re small enough to wash away — wrong. They clump into a sludgy mass over time, especially when mixed with grease. Think of it like building a blockage brick by brick.
Instead: Compost them (they’re great for plants) or bin them.
4. Flour and Dough
Flour + water = paste. Literally. It’s like pouring glue into your pipes. Same with dough — it sticks to everything.
Instead: Wipe out mixing bowls with a paper towel before washing up.
5. Dairy Products (Milk, Cream, Yogurt, Cheese Sauce)
This one surprises people. Milk and cream may seem harmless, but large amounts can solidify with other fats and go sour in your pipes. Also, dairy waste can cause serious environmental harm when it hits the waterways. Farmers can get fined for it — and you could be contributing without knowing.
Instead: Pour it onto old bread and bin it, or use it in compost if applicable.
6. Fruit & Veg Peels, Scraps, and Stickers
Peels can clog or wrap around other debris. And those little fruit stickers? They might look harmless, but they’re made of plastic and don’t break down. They can even mess with wastewater treatment systems.
Instead: Bin all scraps and stickers. Compost what you can.
7. Eggshells
Sharp, gritty, and perfect for catching on rough pipe edges — then everything else gets stuck to them.
Instead: Bin or compost them. Or crush and sprinkle in your garden.
8. Bones, Pips, and Seeds
Way too solid for your pipes. Even tiny seeds can collect and create blockage points.
Instead: Toss them in the food bin or compost if suitable.
9. Honey, Syrups, Custard, and Sauces
Sticky and thick — they cling to pipe walls and trap other bits. Honey in particular can crystallise and harden.
Instead: Rinse containers after wiping them with a paper towel.
10. Paint, Cleaning Chemicals, and Medicine
Paint coats your pipes. Bleach, ammonia, and drain cleaners can corrode them. And meds? They end up in water systems, potentially harming wildlife and water quality.
Instead: Take old meds to a pharmacy. Drop off paint and chemicals at your local waste centre.
Bonus One: Floury or Starchy Water (Like Pasta Water)
It might look like harmless cloudy water, but the starch creates a gelatinous layer inside pipes.
Instead: Let it cool and pour it onto plants or into the compost.
Quick FAQ
Can I pour milk down the sink?
A little in your tea mug? Fine. A whole pint? Please don’t. Dairy clogs pipes, stinks when it sours, and harms the environment.
Can pasta water go down the sink?
Not ideal. It’s starchy and can cause build-up over time.
What can I use to unclog a sink safely?
Try boiling water, followed by a mix of baking soda and vinegar. Avoid harsh chemical drain cleaners unless you know your pipes can handle it.
Is it safe to rinse eggshells down the drain?
Nope. They’re sharp and gritty — they trap grease and build blockages.
Final Thoughts
Look, I get it. You’re busy, and the bin’s across the room. But those two seconds of convenience can cost you big — in plumber’s fees, blocked drains, and potential environmental damage.
Think of your sink like a digestive system — it can only handle so much. Treat it kindly and it’ll keep flowing freely.
Need help with a blocked sink or want advice on how to prevent one? Give us a call — we’ve seen it all (and smelled worse). We’re here to help you keep things moving.
