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What Can You Pour Down the Drain?

“Don’t pour that down the drain, it will clog it!”

Most of us have been admonished by someone about pouring grease or some other substance down a sink or other drain. However, there are far more culprits to a clogged pipe system than bacon grease, and knowing what is safe to flush or drain can save you money and headaches over the long run.

That’s why we’ve put together this comprehensive guide about what not to pour down the drain and how to deal with common household items.

What Not to Put Down Your Drain

While none of these should instantaneously clog a kitchen sink or toilet, over time these items will significantly hurt your plumbing systems and pipes, so don’t put these down them:

There are dozens of other common products that can harm pipes – we always recommend thinking about how a material will react to confined spaces and water before putting it down a drain.

When a Clogged Sink Becomes a Bigger Problem

While specific product and single-drain issues are important to understand and prevent, there is one scenario that requires significant alarm and immediate professional assistance: a mainline clog.

A main sewer line blockage can cause significant property damage as well as contaminate your water. Several telltale signs of this issue are:

Multiple drains are backed up at once: Especially if you have not noticed issues prior and they quickly switched to gurgling, draining slowly, and emitting putrid smells.

Sewage forced up floor drains/sewer cleanouts: If water cannot pass through your main sewer line, then the sewage/wastewater will have to escape elsewhere. This will be either your sewer cleanout, sitting floor drains, or both.

–Water backs up in your shower when the toilet flushes: This is the most common occurrence of displaced wastewater with nowhere to go, but there are other similar issues. These include toilet overflows while using a dishwasher or washing machine – basically anything that creates more water that cannot make it through the sewer lines.

If you experience one or more of these symptoms, it is not the time to poke around and see if you can implement a DIY fix. Call a plumbing professional today in order to save yourself hundreds or thousands of dollars – and most importantly, prevent wastewater from trashing your home and health.

Read More – Chapter 1: 12 Signs You Have a Clogged Drain

Other Considerations and FAQs

Not all things are detrimental to put down sinks and drains, some are actually quite helpful – but there are many household items that can cause some confusion. Here are a few common questions and answers we find helpful:


We highly recommend this practice, and often people ask “why pour salt down the drain?” The answer is that salt will break down grease and emulsified fats by itself, and especially when combined with vinegar and hot water it can contribute to clearer pipes.


Coke and other colas are actually surprisingly decent pipe cleaners, so drain at will! They contain phosphoric acid, which will break down certain buildups in your pipes.


Though not as harmful as grease, Vaseline (petroleum jelly) is a viscous solution that can and will cause clogs.

Paint thinner

Do not pour paint thinner down the drain – turpentine and other mineral solvents used to remove paint will eat away at your pipes and contaminate your water supply.


Ammonia is water-soluble and safe to drain. We recommend you dilute it with plenty of water to reduce harmful effects, and do not mix it with other household products if you do drain it, though.


Antifreeze is a no-go for draining in your home. Ethylene glycol is harmful to your pipes and water supply, and should be contained and disposed of safely – never poured into a drain.


Vinegar is both safe and beneficial to pour down your drain. It acts as a natural cleaning solution and can remove blockages and harmful bacteria that cause foul odors.

Boiling water

Boiling water is typically safe to pour down most drains – but make sure to watch out for you and other people while doing it! In some extreme cases of damaged pipes, it could further degrade plastic seals, but those were likely already in serious jeopardy if water exacerbates it.


Yes – It’s milk. How weak do you think pipes are?

REAL ANSWER: Milk is not necessarily harmful to your pipes and drains, but is extremely harmful to the environment when poured down your drain. Thus, we strongly recommend finding contained solutions or composting milk.


Alcohol is generally safe to pour down a drain in moderate qualities. If you need to dispose of large amounts of it, either dilute it or take time in between draining it so as not to over stress your pipes.

Can you mix baking soda and vinegar to clean drains? 

Though not always the number one recommended long-term solution, baking soda and vinegar along with some hot water can prove to be a serviceable solution to clear your drains.

What can I pour down a smelly sink? 

Baking soda and vinegar can help mitigate foul odors, as well as boiling water + citrus, or even just a soap and water compound. The most important thing is getting all buildup clean from disposals and drains – those are what typically cause foul odors.

Read More – Chapter 4: How to Clean Smelly Drains

Need drain cleaning? Contact Deer Valley Plumbing Today.

At Deer Valley plumbing, we have decades of experience helping homeowners make sustainable decisions to keep pipes and drains healthy. Our plumbing services include preemptive planning so that you won’t be stuck calling us ankle-deep in water.

Read more about how to choose the right plumbing service for your home today. We’d love to have a conversation about saving you time, money, and stress.

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