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    What can’t go down the drain?

    Think twice before committing any of these sink sins

    Hannah | Oneflare
    Updated 18 Sep 2024

    Improper waste disposal, whether by flushing or pouring waste down drains, can have serious consequences for both households and the environment. According to recent trends, waste generation in Australia has increased by 20% over the last 15 years, which includes the waste contributing to sewer blockages and water pollution if not properly managed. 

    Knowing what can and can’t go down your kitchen sink is key to keeping your drain in good shape. Pouring fats, oils, and other thick fluids down the drain can cause blockages that are costly to fix. Luckily for you, this blog post will help guide you through what should and shouldn’t go down your drains, resulting in fewer plumbing issues in the long run. Save yourself the trouble and dispose of the below elsewhere.

    Food scraps 

    Can milk go down the drain?

    fresh milk being poured down the kitchen sink
    Small amounts of milk are okay; too much could cause drainage issues. | Source: iStock

    Milk has proteins and sugars that decompose and can produce unpleasant odours if left in the pipes. It also creates a conducive environment for bacterial growth, which can further worsen odour problems and potentially lead to pipe blockages.

    While small amounts of milk won’t cause big harm, regularly disposing of larger quantities can increase the risk of drainage issues and unpleasant smells in your plumbing system.

    Is it okay to throw orange peels down the drain?

    No, orange peels should not be thrown down the kitchen drain since their tough and fibrous texture can be difficult for plumbing systems to handle. The peels can become entangled in the garbage disposal blades, which may clog or damage your home’s disposal unit. 

    Over time, these can build up and result in slow drainage or even complete blockages, leading to more significant plumbing issues. To prevent these problems, it’s better to dispose of orange peels in a general waste bin.

    Can I put coffee grounds down the sink?

    a man emptying the contents of a coffee capsule in the drain
    Coffee grounds could build up in your pipes. | Source: iStock

    No, you shouldn’t be flushing coffee grounds down your sink. Unlike other organic waste, coffee grounds don’t break down in water and tend to clump together, forming dense, gritty deposits that can build up in pipes.

    Small amounts of natural oils in coffee grounds can mix with grease and fats already existing in your drainage system, solidifying and creating sticky residues that further trap debris. The chemical reactions between coffee grounds and certain cleaning agents can also result in sludge-like substances that are difficult to flush out.

    Can dry ice go down the drain?

    Dry ice is solid carbon dioxide, and when it comes into contact with water or warm surfaces, it sublimates rapidly, turning directly into carbon dioxide gas. This process creates a lot of pressure and can cause bubbling and foaming. 

    If dry ice is drained into your plumbing system, it can result in a sudden release of gas that may lead to dangerous pressure build-ups or even damage to your pipes and fixtures. Additionally, the extreme cold of dry ice can cause thermal shock to your plumbing, potentially leading to cracks or fractures in the pipes.

    Can eggshells go down the drain?

    No, you are not. On the other hand, it is very common to leave some eggshells in the sink and then open the faucet to let the smaller pieces run down the drain. However, they are another of the most harmful things for the useful life of the drain because the membrane of the shells can adhere to the walls of the pipes.

    Are tea leaves allowed down the drain?

    Tea may be good for us, but not so much for the drain. If you use loose leaf tea, make sure that as few leaves as possible make it down the drain as they can build up and create a large problem.

    Cooking oils and fats

    Can you dump grease down the sink?

    a used pan and scrubber in the kitchen sink
    Pouring oil in your sink could clog your pipes. Source: iStock

    When grease is poured down the sink, it initially flows with the water but quickly begins to cool as it moves through the plumbing system. As it cools, grease solidifies and forms a thick, sticky residue that clings to the pipe’s interior walls, narrowing the canal and restricting water flow.

    Over time, this solidified fluid can mix with other substances like soap scum, food residues, and hair, forming larger and more stubborn blockages. These blockages, often referred to as “grease clogs,” can cause slow drainage and eventually result in complete pipe obstructions. In severe cases, the accumulation of grease can lead to plumbing backups and expensive repairs.

    Can oil go down the drain?

    Similar to grease, you shouldn’t pour cooking oil down your kitchen sink, since it cools and solidifies after it cools. As it hardens, it sticks to the interior walls of pipes, creating a residue that can gradually accumulate and narrow the pipe’s interior, leading to identical blockages attributed to throwing grease down the kitchen drain.

    Can you pour butter down the sink?

    Pouring butter down the sink is not advisable. Butter hardens when it cools, which can clog your drains. Not only that, but butter mixing with dirt and debris already in the drain can lead to more headaches, since they can prove to be more stubborn to manually remove than others. 

    Instead of tossing butter in your kitchen drain, you can dispose of it in the trash or let it cool and harden, then scrape it into a compost bin if applicable. By doing this, you can prevent potential clogged drains.

    Cleaning products and other chemicals

    Can you pour chemicals down the sink?

    a woman cleaning the kitchen sink
    Throwing chemicals down the drain could damage it in the long run | Source: iStock

    Avoid pouring large quantities of chemicals like drain cleaners or toilet cleaners down the sink. Doing this regularly can damage your pipes, cause leaks, and potentially contaminate your home’s water supply. Over time, this can also compromise the integrity of your plumbing system and affect the safety of your immediate living environment.

    Can you pour boiling water down the sink?

    It’s generally safe to pour boiling water down the sink if your pipes are made of metal or high-quality PVC. If your pipes are old, made of plastic, or have a PVC system, boiling water can potentially cause damage by softening or warping the material over time.

    If you are pouring boiling water down the drain to try and clean away a blockage you may need additional products to help it along. Grease or food scraps may require manual unclogging, instead of just boiling water.

    Can you wash acrylic paint down the sink?

    a person washing their hands in a sink
    It’s always better to check how to clean your hands properly after painting. | Source: iStock

    No, you shouldn’t wash acrylic paint down your sink because it can cause long-term damage to your plumbing, even if you don’t notice it in the beginning. Acrylic paint contains plastic particles that can stick to the inside of pipes or impact it negatively, leading to buildup that can interfere with water flow and potentially lead to blockages. 

    Can you pour bleach down the drain?

    Bleach is a strong, corrosive chemical product that can damage certain types of pipes, especially if they are older or made of materials like PVC. Repeated exposure to bleach can cause the pipes to deteriorate or weaken, increasing the risk of leaks.

    Additionally, exposing bleach to other substances in your drain can result in heat and gases which could put stress on your drain system. Without proper care or attention, this can lead to cracks, leaks, and other damages. 

    Tips to prevent clogging your drain

    a woman using a large sponge to clean the sink
    Clean your drain or sink regularly for proper maintenance. | Source: iStock

    Keeping your kitchen drains clean and in their best shape is important for a healthy plumbing system in the long term. Practising regular maintenance and understanding how to detect potential issues early are just some of the plumbing tips and tricks you can do to avoid costly repairs in the future.

    1. Clean your drains regularly

    Use a mixture of hot water and baking soda or vinegar once a month to flush out minor build-up. This natural solution helps dissolve grease, soap scum, and other residues that can clog your pipes over time. 

    2. Use drain screens or drain filters

    You can install drain screens to prevent hair, food particles, and other large debris from entering the pipes. Not only are these cost-effective, but they also get the job done really well, and can significantly reduce the risk of clogs in your plumbing system.

    3. Research tell-tale signs of issues

    Slow-draining sinks, gurgling sounds from drains, or water backing up in unusual places are common indicators of a developing blockage. Unpleasant odours emanating from drains can also signal a buildup of debris or trapped gases in your pipes.

    4. Properly dispose of grease and oils

    Instead of pouring leftover grease, oils, and fats down your drains, you can collect them in a container and dispose of them properly after they’ve cooled and hardened. 

    5. Schedule professional checkups and cleaning

    To make sure your pipes are in good condition, be sure to have regular inspections and cleanings. A licensed plumber can identify potential issues, like hidden leaks, corrosion, or early signs of blockages before they become major problems. 

    Professional cleaning can remove stubborn build-up that household methods might miss. It’s advisable to schedule annual or bi-annual checks so your plumbing system is operating at its best.

    Keep your drains flowing

    Proper drain care is a must for a healthy plumbing system in your home. While it’s not common for things to find their way into your drains, you should be able to recognise what can and can’t go down the pipes to avoid inconveniences and financial headaches in the future.

    Already committed these sink sins? It’s always best to consult a professional who can help you solve your drain problems to keep them in top condition.


    FAQs on drain safety

    Does ammonia damage PVC pipes?

    Most household plumbing systems can handle occasional exposure to ammonia without immediate harm. However, the issue arises when ammonia mixes with other chemicals, particularly those containing chlorine, as this can create toxic fumes and potentially corrosive compounds.

    Can you pour flour down the sink?

    Pouring flour down the sink is not recommended. When mixed with water, flour forms a sticky, paste-like substance that can easily cling to the inside of your pipes. Over time, this paste can build up and create blockages, especially when combined with other debris or grease. These clogs can be difficult to remove and may lead to costly plumbing repairs.

    Is bleach or vinegar better for drains?

    When it comes to cleaning drains, vinegar is generally a better choice than bleach. Vinegar, especially when combined with baking soda, is effective at breaking down grease, soap scum, and other organic build-up in your pipes, and it also helps neutralise odours. It’s non-toxic, environmentally friendly, and safe for regular use without damaging your pipes.

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