How to safely turn your old toothbrush into a household cleaning tool

Toothbrushes can be handy around the house—as long as you clean them first.

The next time you replace your toothbrush, don’t throw it out. It might be far past its prime for cleaning your pearly whites, but it can serve you well around the home for months, or even years.

For the most part, the possible uses for an old toothbrush are limited only by your imagination. It’s important to remember, however, that those bristles picked up a lot of plaque and bacteria while they worked, and you don’t want to inadvertently upcycle your cuspid cleaner into a germ-spreading wand.

How to clean an old toothbrush

Dentists generally recommend replacing your toothbrush every three months, and some suggest swapping it out after an illness to eliminate the possibility of reinfection. That’s because after regular use, your brush has spent quite a bit of time tussling with soggy bits of stuck food and other unpleasant oral invaders. Nasty. Clean it before you use it for anything else.

All you need for this is some bleach and water. Dr. Domenica Sweier, a clinical professor at the University of Michigan School of Dentistry, recommends soaking the brush in a 10 percent bleach solution (one part bleach, nine parts water) for a few minutes. Finish by rinsing your upcycled tool. For added safety and a true fresh start, sanitize the whole thing—bristles and handle.

[Related: How to be a responsible adult and brush your teeth properly]

Sweier does not recommend using an old toothbrush for any job that will bring it into direct or indirect contact with food or anything that goes into your mouth. She says there’s no way to entirely sterilize a worn toothbrush without physically damaging it, and any remaining pathogens could harm you and your family. “These are the germs that have survived through use and surface cleaning, so they are the robust ones,” she says.

How to use an old toothbrush around the house

It’d be impossible to cover all the possible uses for a small brush, so we’ll paint in broad strokes while offering a few crucial tips. First, consider labeling the brush with a permanent marker, especially if you’re going to use it to clean tile grout, faucets, or anything else in the bathroom. The last thing you want to do is discover you’ve absentmindedly stuck the toilet bowl cleaner in your mouth.

An old toothbrush is truly indispensable for cleaning small, hard-to-reach areas, and that’s what you should use it for. Whip it out when you need to brush off a bicycle chain, sawdust-covered tools, your computer keyboard, blinds, the tops of your baseboards, and jewelry. Keep in mind that more delicate tasks, like cleaning jewelry and electronics, will require softer bristles. We’ve had great success using one to scrub dirt and mud off of boot soles and cleats.

You may find a toothbrush handy for spot-cleaning carpets and clothes, particularly if you want to scrub out a stubborn stain. If you do this, though, make sure you don’t brush too hard and ensure there’s no bleach left on the bristles—you don’t want to trade that jelly blob for a colorless splotch.

[Related: Stain removal tips from a Buckingham Palace-trained butler]

If you find the length of the toothbrush handle unwieldy, you can carefully cut it in half. We found a simple pocket knife was up to the task, but you can also use a hand saw. Do not use a power saw because the plastic could shatter, splinter, or shoot off in unpredictable directions.

Using a toothbrush in the kitchen

While Sweier does not recommend bringing a used toothbrush into the kitchen, she doesn’t consider new, unused toothbrushes an infection risk. Still, she cautions that bristles could fall out and end up in your food.

That risk is inherent with brushes, whether they’re toothbrushes, bottle brushes, wire grill brushes, or anything else. You can dramatically reduce the risk of eating loose bristles by rinsing everything thoroughly after it’s been scrubbed down.

With those safety notes in mind, toothbrushes are excellent for cleaning blender blades, can opener gears, waffle irons, and the threads at the mouth of a mason jar.

John Kennedy

John Kennedyis PopSci's DIY editor. He previously covered legal news for Law360 and, before that, local news at the Journal Inquirer in Connecticut. He has also built and remodeled houses, worked as a fencing coach, and shelved books at a library. When he's not taking things apart or putting them back together, he's playing sports, cooking, baking, or immersed in a video game. Contact the author here.