If you discover that the toilet has developed a stubborn clog, you might be tempted to blame the problem on a mischievous toddler in your household. Perhaps they decided to let their plush whale go for a swim and now it's stuck in the U-bend.

However, the plumbing can easily become gummed up by a number of common objects. If you treat the toilet like a garbage can, tossing in any items you'd like to be flushed and forgotten, you can easily find yourself stuck with a costly repair bill from a plumber.

Several items are commonly mistaken for flushable objects. Some might even sport a prominent "flushable" label. However, this designation is usually misleading. Brett Van Alstine, writing for the home design site The Spruce, says flushable sanitary wipes may dissolve in water, but not nearly as effectively as toilet paper. As such, there's a risk that the wipes may form a clog in the pipes.

Other items won't claim to be flushable, but look similar enough to toilet paper that you may believe they are safe to flush. Nichols & Phipps, a plumbing company in Woodbridge, Va., says tissues can usually be flushed if they are thin and you don't put too many in the bowl. But with plenty of companies boasting of thicker, more comfortable tissues, even this item can plug up the toilet.

Similarly, paper towels should never be flushed. Since they are much larger than toilet paper squares and designed to absorb moisture, paper towels will not move easily through your plumbing.

Other types of wipes and towels, including baby wipes and makeup removers, can also be prone to causing clogs. The magazine Family Handyman says cotton products, such as cotton balls and swabs, are particularly troublesome since they will absorb water, expand, and clump together.

It can be tempting to use the toilet as a convenient way to dispose of items, especially smelly ones you don't want to leave in the trash. Cat owners often keep the litter box in the bathroom, but you shouldn't put any of this waste or litter into the toilet bowl. Mario Angeloni, writing for the home design site Houzz, says kitty litter will clump when it gets wet, so it can easily block pipes. Family Handyman says that even if the litter is deemed flushable, it can still accumulate gradually in your plumbing.

Parents of young children may think to toss dirty diapers into the toilet. But disposable diapers are meant to be thrown away, not flushed away. A diaper will absorb water and expand, making it very likely that it will get stuck somewhere in your pipes.

You might toss other items into the toilet instead of the trash can because you think their small size won't lead to any plumbing problems. Even if they are small enough to fit through the pipe, however, they can still lead to clogs or problems with your sewage system.

Many of these items won't break down easily. Tampons, condoms, bandages, and anything else with plastic or rubber components will not be biodegradable. They can make their way a good distance down your plumbing before getting caught, and linger there with the potential to cause problems in the future.

Floss and hair can be especially problematic. Van Alstine says while they might seem innocuous, the strands can become tangled with one another and form blockages.

Avoid putting any sort of food into the toilet. You may think grease can be emptied into the bowl and flushed away since it's a liquid, but it will quickly solidify in the pipes. Chewing gum won't break down in the water, so you should spit it out into the trash instead of the toilet.

Some items can contaminate your water supply or cause other problems. Cigarettes contain plenty of carcinogens and other toxins, and it's wasteful to dispose of your smokes this way since each flush typically uses more than a gallon of water. While a flush is often seen as the best way to send off a dead goldfish, doing so can clog the plumbing or pollute the water system; flushing a live fish this way can introduce an invasive species to a nearby waterway.

It is a good idea to get rid of old medications, but flushing them can be harmful to marine life. It is preferable to find other ways to throw them out, such as prescription disposal boxes at your local police station or senior center.

In general, it's a good rule of thumb to not put anything in the toilet other than bodily waste and toilet paper. You'll even want to be careful about how much toilet paper you put in the bowl before a flush. Nichols & Phipps says too much will create a sodden mass which can plug a pipe, especially if you are using a thicker type of toilet paper.

The same rules apply to septic systems, but these can be even more vulnerable to improper materials being flushed. The septic tank operates as a biological system, with beneficial bacteria breaking down wastes. The Columbia Shuswap Regional District, a Canadian municipal service, says grease and food scraps can overwhelm the system if they are poured down the toilet or sink.

Although many liquids won't cause clogs if poured into the toilet, they can kill the bacteria in a septic system and prevent it from working. These materials include solvents, paints, fuels, and pesticides. Homeowners with septic systems should also use chemical cleaners sparingly when cleaning the bathroom, since these can also kill the bacteria in the system.