What Not to Flush Down Toilet: Things You Should Never Flush

Knowing what not to flush down toilet can save you from a clogged toilet, huge repair bills, and damage to rivers and oceans. A simple rule helps: only the 3 Ps should go down your toilet — pee, poop, and toilet paper that is designed to dissolve in water. Everything else, even if the label says “flushable,” can cause problems.

Water utilities report that wipes and fats are now behind the majority of sewer blockages. In the UK, water companies found that wipes made up about 93% of the material in sewer fatbergs, with baby wipes alone accounting for around 75% of blockages they studied. Utilities also spend tens of millions each year clearing these messes. Homeowners pay too: a basic clog can cost well over a hundred dollars to clear, while a damaged sewer line can run into the thousands.

In this guide, you’ll get a quick answer list, clear item-by-item explanations, real-world plumbing and environmental impacts, common myths, and simple ways to dispose of risky items safely.

What not to flush down toilet: Quick Answer

Before we go deep, let’s answer the big question fast.

The 3 Ps rule: what you can flush safely

Your toilet and plumbing system are built for one purpose: carrying away human waste and paper that breaks down fast in water. That means only:

Urine (pee)
Feces (poop)
Toilet paper that is designed to break down in water

Good toilet tissue falls apart quickly in moving water. It does not stay strong, it does not wrap around other things, and it does not act like a net when you flush.

Anything else you send down the toilet — even if it looks like paper, even if the label says “flushable” — can cause clogs in your pipes, your sewer, or your septic system.

Quick-reference: items that should never be flushed

If you want a simple mental checklist of things you should never flush, remember these groups:

Wipes of any kind (baby wipes, cleaning wipes, makeup wipes), even “flushable” or “plastic-free”
Sanitary products (tampons, pads, liners), diapers, incontinence pads
Cotton items like cotton balls, cotton pads, and cotton swabs/Q-tips
Hair and dental floss
Paper towels and tissues (including Kleenex-type facial tissues)
Food scraps, coffee grounds, rice, pasta, and grease, fats, and oils
Cat litter, pet waste, and aquarium gravel
Medications, pills, and household chemicals
Condoms, masks, gloves, and cigarette butts
Small objects like toys, bandages, and plastic wrappers

These items that shouldn’t be flushed either don’t break down in water, are meant to absorb water, or are sticky and insoluble. They stick to pipe walls, snag on rough spots, and help form large clumps called fatbergs.

Top Everyday Items You Should Never Flush (And Why)

So what should you not throw in the toilet in real life? Let’s look at the most common mistakes and why they cause trouble.

Wipes, paper towels, and “flushable” products

You might see a pack of wipes that says “flushable” in big letters. But water utilities say wipes don’t break down like toilet paper.

Toilet paper is designed to break apart as soon as it hits toilet water and moves through pipes. Wipes, on the other hand, are made to stay strong when wet. Many contain long fibers (often plastic-based) that don’t break down in water.

The same goes for paper towels and tissues. These products are meant to absorb water and hold together. That’s why they’re great for wiping spills, but terrible for your drain. They don’t break into small pieces fast enough, so they get stuck at bends and joints in your pipes.

Over time, flushed wipes and paper towels:

Catch on rough spots inside older pipes
Wrap around small roots or cracks
Mix with grease and fats to make sticky and insoluble clumps
Form the base of fatbergs in sewers

Water companies in the UK found that wipes made up the vast majority of the material in sewer blockages they studied. These clogs can be several meters long and weigh many tons.

So even if the packet says “flushable,” it’s safer to avoid flushing any wipe at all. Throw them in the trash instead.

Sanitary products, diapers, and incontinence items

Sanitary pads should never go down a toilet. Neither should tampons, liners, menstrual cups, diapers, or incontinence pads.

These products are meant to absorb water and swell. They often contain super‑absorbent gels and plastic layers. In a pipe, that means:

They grow larger as they take on water.
They wedge tightly in narrow spots.
They never dissolve like toilet paper.

A single tampon string can catch on a small rough area inside a pipe. Once it snags, it becomes a sort of net when you flush, trapping hair, wipes, and other debris. Diapers and large pads are even worse; they can block a pipe almost instantly and cause a clogged toilet that a normal plunger can’t clear.

If you want your pipes to stay clog‑free, always wrap these items in toilet paper or a small bag and place them in the bathroom trash.

Cotton, hair, and dental floss

Cotton seems natural and soft, so many people think it is safe. But cotton balls, makeup pads, and cotton swabs or Q‑tips don’t break down in water the way toilet paper does. They stay in clumps, soak up water, and then sit inside pipes like sponges.

Hair will never dissolve in water. Whether it’s long hair from a brush or short shaving stubble, hair never dissolves in your plumbing system. Instead, it tangles with itself, with soap scum, and with wipes and cotton. It turns into a net that grabs everything passing by.

Dental floss is usually nylon or Teflon. It also doesn’t break down in water, and it acts like fishing line. When you flush floss, it can:

Wrap around moving parts in pumps at treatment plants
Tie together clumps of wipes, cotton, and hair
Add strength to blockages so they’re harder to remove

So instead of flushing hair or floss, put them in the trash. For hair that sheds in the shower, use a simple drain catcher and empty it into a bin.

Can you flush paper towels, tissues, or tampons?

People often ask this as one big question: “Can you flush paper towels, tissues, or tampons?” Here’s a simple comparison of how these items behave compared to toilet paper.

Toilet paper – Made to disintegrate within minutes in moving water; very low clog risk in normal use.
Facial tissues (like Kleenex) – Built to stay strong when wet; tend to stay intact much longer and can build up in bends.
Paper towels – Very tough and absorbent; can block pipes quickly, especially if flushed in bunches.
Tampons and pads – Meant to absorb and expand in water; never be flushed because they can block even wide pipes.

Fats, Food, Medications, and Cat Litter: The Hidden Threats

Not all flushing problems look like trash. Some are less obvious but just as harmful.

Food waste, oils, and grease (“FOG”)

Here’s what happens when food goes down your toilet:

Rice and pasta swell as they absorb water and can form a paste that clogs pipes.
Coffee grounds settle and pack tightly in low spots in your drain.
Bones, fruit pits, and tough scraps don’t break down and can get stuck at joints.
Greasy sauces and bits of fat coat the inside of pipes, making them sticky.

Add fats, oils, and grease (often called FOG) and things get worse. When hot grease cools, it hardens on pipe walls. Wipes and other debris stick to it, and over months or years you get a thick, hard blockage. These fatbergs have to be broken up by crews and heavy tools.

So never flush grease or pour it down any drain. Let it cool in a jar or can, then throw it in the trash. Scrape plates into the bin or compost before washing.

Medications and pharmaceuticals

Flushing old pills might feel like a safe way to get rid of them. But flushing it down the toilet sends drugs straight into the water system.

Most wastewater treatment plants are not designed to fully remove pharmaceuticals. Studies by the US Geological Survey and others have found residues of painkillers, antibiotics, hormones, and other drugs in rivers and lakes downstream from treatment plants. These chemicals can affect fish and other aquatic life, sometimes changing their growth or behavior.

That’s why health and environmental agencies say: never flush old medicines. Use drug take‑back programs, pharmacy drop boxes, or mail‑back envelopes where available. If none of those are an option, follow local rules on mixing medicines with something unappealing (like used coffee grounds) and sealing them in the trash.

Cat litter, pet waste, and aquarium debris

Flushing cat litter down the toilet or pet poop might seem like an easy cleanup. But it causes several problems:

Clumping litter is designed to absorb water and form hard lumps. Those lumps can jam in bends and cause a blockage.
Even “flushable” litter often doesn’t break down fast enough and can overload a septic tank.
Cat waste can carry Toxoplasma gondii, a parasite that can survive some treatment steps and harm marine animals, including sea otters.

Aquarium gravel, sand, and small plastic decor also never dissolves. They are denser than water and sink into low points in pipes where they can build up.

So, “Is it OK to flush old medicines or kitty litter?” No. Both should never be flushed. Litter and pet waste go in the trash (in a sealed bag). Medicines go to a take‑back or safe disposal program.

How Flushing the Wrong Things Damages Plumbing and Sewers

It helps to imagine what happens after you flush down your toilet.

What happens in your home’s pipes

From your toilet bowl, waste moves into a short pipe, then into a larger drain that serves the bathroom, then into a main pipe that leads out of your home.

In newer homes, these pipes are often smooth PVC. In older homes, they may be cast iron or clay. Over time, older pipes can have scale, tiny cracks, and even small tree roots growing through joints.

When you flush down the toilet items that don’t break apart — like wipes, hair, cotton, or gum — they can:

Catch on the smallest rough spot or root hair
Begin to pile up, one piece at a time
Mix with grease and soap to form sticky layers

At first, you might not notice anything. Then you see the toilet draining slowly, or you hear gurgling in a nearby drain. That is often the sound of a blockage starting to form.

From house to street: sewer mains, pumps, and treatment plants

After leaving your home, waste travels through a sewer main under the street. It may pass through pump stations before reaching a treatment plant.

In these bigger pipes, the same rule applies: items that don’t break down in water cause trouble. When wipes, grease, and solids meet, they form fatbergs — huge, solid masses that stick to the pipe walls.

Water companies have reported fatbergs:

The size of buses
Hundreds of feet long
Weighing tens of tons

Removing them takes weeks of work and costs cities large amounts of money. Pump stations can also fail when wipes and hair wrap around impellers and motors, forcing expensive repairs.

When sewers clog, wastewater can back up into basements or overflow into streams and rivers, carrying pathogens and trash with it.

Real-world examples and homeowner costs

Many utilities now run “only flush the 3 Ps” campaigns because they see the damage every day. Some report spending the equivalent of tens of millions of dollars each year dealing with wipes, fats, and other items that shouldn’t be flushed.

For a homeowner, the price tag is more direct:

A simple clogged toilet cleared with basic tools can cost as much as a family dinner out.
A main sewer line blocked by wipes, roots, and grease can cost several hundred dollars for a plumber to clear.
A cracked or collapsed sewer pipe that must be dug up and replaced can cost several thousand dollars.

Most of these costs are avoidable by truly avoiding flushing anything beyond the 3 Ps.

Environmental and Health Impacts of Flushing Non‑Flushables

Bad flushing habits don’t just hit your wallet. They also reach far beyond your home.

Water pollution and aquatic ecosystems

When wipes, plastics, and synthetic fibers bypass treatment or escape in sewage overflows, they break into microplastics. These tiny pieces can be eaten by fish and other creatures, moving up the food chain.

Food scraps and grease that get past treatment can add extra nutrients to waterways, which may fuel algae growth. Thick algae blooms can reduce oxygen levels, stressing or killing fish.

Pharmaceuticals, chemicals, and hazardous waste

As research has shown, traces of antibiotics, painkillers, hormones, and other drugs are found in many surface waters. Even at low levels, they can affect the growth, behavior, or reproduction of some aquatic species.

When people flush paint, solvents, or pesticides, they send toxic environmental effects downstream. Treatment plants are not built to handle these chemicals. Some can harm the helpful bacteria used in treatment; others can pass through and affect wildlife.

Wildlife, beaches, and public health

Items you never flush down your toilet, like condoms, sanitary pads, wipes, and cigarette butts, can end up on riverbanks and beaches after overflows or storms. Animals may mistake them for food or become entangled in them.

When sewer systems are stressed by blockages, there is a higher chance of overflows carrying germs that cause illness. That can affect swimming areas, shellfish beds, and drinking water sources.

Myths, Labels, and Common Questions About Flushing

A lot of confusion comes from product labels and old advice passed down in families.

Myth-busting “flushable” and “biodegradable” claims

Many products are sold as:

“Flushable”
“Septic safe”
“Biodegradable”
“Plastic-free”

The key point is that “will break down one day” is not the same as “safe to flush now.”

Water agencies test whether items dissolve in water quickly and pass through pipes without causing clogs. Many products that pass “flushability” tests from manufacturers still fail the tests used by utilities.

So when a wipe maker says “flushable,” that does not mean your local water utility agrees it is good for your pipes or their sewer.

Is it safe to flush hair, gum, or cigarette butts?

People also ask about small items: “Can I flush hair?” “What about gum or cigarette butts?”

Flushing hair – As mentioned, hair never dissolves and acts like a tangled net in pipes and pumps.
Gum – Gum never dissolves in water. It stays sticky and can glue other debris together.
Cigarette butts – They have plastic fibers and filters that don’t break down. They also carry chemicals that can leach into water.

So even small things can cause clogs and add chemicals and plastics to waterways. These items you should never flush belong in a bin.

Old advice about hot water, bleach, or drain cleaners

You may have heard that pouring boiling water, bleach, or strong drain cleaners down your toilet will “clear everything out.”

Here’s why this is risky:

Boiling water can soften or crack some kinds of plastic pipes.
Bleach can harm the helpful bacteria in your septic tank or at the treatment plant.
Drain cleaners can corrode older pipes and still can’t fix solid obstructions like wipes, toys, or clumps of hair.

Safe options for small build‑ups are gentle enzyme cleaners, regular plunging, and good flushing habits. For bigger clogs, a professional plumber with the right tools is safer than harsh chemicals.

How to Dispose of Non‑Flushable Items Safely

Knowing what should never be flushed is only half the job. You also need easy disposal options so you aren’t tempted to “just flush it this once.”

Bathroom trash setup and daily habits

A simple setup makes good habits easy:

Put a small lidded trash bin in every bathroom.
Use liners (compostable or regular) so emptying is easy and clean.
- Compostable liners reduce environmental impact
- Regular liners are convenient and widely available
Empty the bin often, especially in guest or kids’ bathrooms.

For wipes, sanitary products, and condoms, wrap them in a bit of toilet paper or a small bag before placing them in the bin, especially if you share a bathroom and want more privacy.

Teach kids a simple rule: “Only pee, poop, and toilet paper go in the toilet. Everything else goes in the trash.”

Food scraps, fats, oils, and grease disposal

Instead of flushing food, try these habits:

Scrape plates and pans into the trash or compost before rinsing.
Pour used cooking oil and grease into a can or jar. When it cools and hardens, put the closed container in the trash.
If your area has a cooking oil recycling program, collect oil in a larger jug and drop it off when full.

This keeps sticky fats out of pipes and helps keep your plumbing system in better shape.

Safe ways to get rid of medicines and household chemicals

For medications:

Look for a drug take‑back day in your area.
Some pharmacies have secure drop boxes.
Mail‑back programs allow you to send unused meds in a pre‑paid envelope.

For chemicals like paint, solvents, and pesticides, check your city or county website for household hazardous waste collection days or sites. These programs help keep toxins out of sewers and landfills.

Kid‑ and guest‑proofing your bathrooms

To prevent accidents:

Keep cleaners, medicines, and sharp items out of reach of children.
Put a small, clear sign near the toilet in guest baths with the 3 Ps rule.
Make sure there is enough water in the tank and bowl for a proper flush, and never ask guests to flush wipes.

If someone does flush a non‑flushable by mistake, act fast:

If the item is still visible, turn off the water and try to remove it by hand (with gloves) rather than flushing again.
If flushing has already happened and the toilet drains slowly or not at all, stop using it and call a plumber before the backup spreads.

FAQs

1. What should you not throw in the toilet?

Knowing what not to flush down toilet is essential to prevent plumbing issues and protect your water supply. Only pee, poop, and toilet paper are safe. Certain items like wipes, tampons, hair, cotton balls, and food should never flush down the toilet, as they can clog pipes and damage your plumbing system.

2. What will clog the toilet?

Many certain items can clog your toilet. Wipes, paper towels, cotton, tampons, and hair are all examples of what not to flush down toilet. Flushing them may lead to plumbing issues, blockages, and damage to your water supply, so always use the trash for these items.

3. Can I flush hair down the toilet?

Can you flush hair down the toilet? No. Hair never dissolves in water, and will tangle with other debris. Will hair clog a toilet? Yes, flushing hair can create serious plumbing issues. Hair is one of the most common examples of what not to flush down toilet, so always discard it in the trash.

4. Can I flush food down the toilet?

Never flush food down your toilet. Rice, pasta, coffee grounds, and grease are certain items that swell or stick, forming blockages. These are classic examples of what not to flush down toilet, as they can cause plumbing issues and harm your pipes and water supply.

5. Can you flush Kleenex down the toilet?

Kleenex and other facial tissues are not designed to dissolve in water. Never flush down the toilet Kleenex or similar items. Certain items like this are prime examples of what not to flush down toilet, as they can clog pipes, create blockages, and lead to plumbing issues.

References

https://www.epa.gov/septic/how-care-your-septic-system