Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

If you have a septic tank system, you probably know well how important it is to maintain it regularly and by using the proper methods. One of the most common septic system issues that can lead to septic system failure and sewer backups is clogged waste and this results mostly from items that don’t belong to the septic tank.

Sewage system backups are more serious than slow-draining siphons. A sewer backup is when an unpleasantly smelling black water overflows from your toilet, bathtub, or some drain at your property. 

The main cause for this is a clogged septic drain. And the best way to avoid this sewer issue from happening is to know what things you should and should not flush down your septic drains. 

If you are interested in keeping your septic tank system in  good condition and avoiding costly repairs and unpleasant sanitary sewer overflow (called SSO).

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

There is a list of things that aren’t recommended for flushing down septic drains as they can lead to a risk of sewer backup. 

To avoid septic tank system failure and blocked sewer pipelines, just make sure that you are not using your drains for garbage disposal. This is one of the worst things you can do when maintaining your septic tank system.

Do Flush Septic-Safe Toilet Paper

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

Toilet paper is considered one of the septic-safe commonly-flushed items you can flush down your toilet. The fact that it’s biodegradable makes it a suitable item for flushing. Together with human waste toilet paper is a septic-safe option for flushing. 

One important thing you should know is that when flushed once in a while toilet paper won’t lead to a serious septic system failure. But if you flush down too much toilet paper on a daily basis, the risk of septic tank system failure will inevitably increase.

Despite the fact that it’s biodegradable when flushed down in large amounts, toilet paper can cause clogs in small-size drain pipes. 

Although they are the perfect alternative to toilet paper, large wads of paper towels or facial tissues are also not recommended to end up in your septic system. Unlike toilet paper, the different paper products you can find in stores are designed for absorbing water and not for dissolving in it. 

Paper towels and facial tissues are thicker than toilet paper and for this reason, they are more likely to cause septic drain clogs.

Don’t Flush Feminine Hygiene Products

To keep your septic system healthy avoid flushing down the toilet all types of feminine hygiene products such as sanitary pads and tampons. 

The main purpose of these products is to absorb liquid and for this reason, they have the ability to swell and  increase their size several times. As a result, they can lead to sewer system backup.

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

Do Flush Septic-Safe Cleaning Products

The use of septic cleaners is an essential part of the routine maintenance of every septic tank system. Experts recommend the use of such septic cleaners that are septic safe.

Don’t Flush Dead Fish

You may have heard that some people flush down the toilet their dead pet fish. This isn’t something that sewer experts recommend as dead fish doesn’t break down in the water and it leads to a risk of clogged septic drains. 

To avoid future problems with your septic tank system just place your dead fish in a paper bag or a container from a biodegradable material and bury it.

Here we can conclude that everything that isn’t biodegradable isn’t suitable for flushing down septic drains. 

Other things you shouldn’t flush

Wet wipes and baby wipes

One proof that you should not always believe what is written on product labels is that even those wipes that are labeled “flushable” shouldn’t be flushed down septic drains because they don’t break down quickly and can create a risk of clogs inside your drain pipes.

Dental floss and hair

Dental floss isn’t biodegradable and it can be considered at first sight as septic-safe because of its small size. But flushing your dental floss down the toilet every day isn’t recommended.  Dental floss still has the potential of causing blockages inside septic drain pipes.

Similarly to dental floss hair isn’t considered a major factor for septic system failure. But when flushed often hair clumps can adhere to the inner walls of the drain pipes and  lead to drain pipe clogs.

One way to limit the amount of hair going into your septic system is to use sink and shower drains.

Cotton balls/swabs/Q-tips

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

Although cotton products such as cotton balls and Q-tips are small in size when flushed down septic drains often they can lead to blockages inside them and even lead to broken/bent pipes over time. 


Medicine and drugs are other items you should avoid flushing down your septic drains. Just like commercial household cleaners they can also cause wastewater pollution in septic tank systems. You can safely dispose of expired medical drugs by using drug disposal sites instead.

Similarly to cotton swabs and wet wipes bandages are made from a non-biodegradable plastic that doesn’t allow them to break down in the water and have the potential to cause some major septic system issues.

Because bandages have sticky adhesive sides they can easily get stuck on other items in your septic system and cause some major drain clogs. The plastic material bandages are made of can not only cause drain clogs but it can also pollute wastewater systems.

Oils, grease and fat

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

Other things you should never pour down your septic drains are different oils, fats, and grease. Despite the fact that they come in a liquid form these items become solid after cooling down and can get stuck on the walls of drain pipes. 

When periodically flushed down over time any type of grease, cooking fat, or motor oil will lead to buildups inside drain pipes and limit the water flow. So, you should always throw the oils, grease, and fat you use in your household in the trash after they are fully cooled down.

Paint and commercial cleaning products 

Can I Flush That? A List of Items You Should and Should Not Flush When You Have a Septic System

Paint and paint thinners are one of those household items that contain harsh chemicals that can disrupt the healthy bacterial balance inside a septic tank and decrease its efficiency in sewage water treatment.

Household cleaning products such as window, floor, or  oven cleaners and also household bleach are also not recommended for flushing down septic drains. If you want to dispose of or recycle hazardous household materials, then you should check for the nearest collection site in your local area. 

Cat litter

Some of us may think that if toilet drains are designed for human waste, they can be used for cat waste as well. But this isn’t the case if you want to use your toilet to dispose of your cat’s litter.  

Cat litter falls in the category of solid waste, so this means it can lead to clogs inside septic drain pipelines. Besides, it can also lead to wastewater pollution as it contains harmful parasites which wreak havoc on the balance of healthy bacteria living in septic tanks.

Coffee grounds and cigarette butts

It may seem convenient for some of us to use our toilet for disposing of everyday waste such as cigarettes and ground coffee waste but this is something that is a major no-no for your septic tank system.

To conclude, keeping a trash can handy in your bathroom is one of the simple things you can do to protect your property from sewer system backups and clogged drain pipelines.