Rinsing your mouth with water after brushing your teeth is a common habit for many of us, but experts say it could actually be doing more harm than good.

I used to do it for years, but I've recently managed to break the habit at the suggestion of my dentist — though I still haven’t gotten around to flossing yet, oops!

But seriously, who has time for that? I’m sure some of you are reading this with disbelief — it just seems too tedious for me and takes way too long.

In any case, there's actually a surprising reason why rinsing your mouth after brushing isn't a good idea.

As we've mentioned before, rinsing your mouth immediately after brushing is a big mistake, as Dr. Arash Ravanbakhsh, a Canadian dentist and owner of Inglewood Family Dental in Calgary, explained to the New York Post. "After brushing, you should spit out any remaining toothpaste," he said.

"Rinsing with water right after brushing washes away the fluoride, which helps protect against issues like tooth decay."

Fluoride is a naturally occurring mineral that was first added to public water supplies in the US during the 1940s for oral health purposes. It’s well-known for reducing cavities and tooth decay.

So effective, in fact, that the Centers for Disease Control and Prevention (CDC) calls water fluoridation "one of the 20th century’s greatest public health achievements."

Scottish dentists Clement Seeballuck and Nicola Innes, both from the University of Dundee, also explained in an article for The Conversation why it's important not to spit out the fluoride. "At night, saliva production decreases, which means your teeth have less protection and are more vulnerable to acid attacks," they wrote.

"That’s why it's crucial to remove food particles from your teeth before bed so plaque bacteria can’t thrive overnight. Don’t eat or drink anything except water after brushing at night. This also gives the fluoride the longest time to work."

They continued: "Once you’ve brushed, don’t rinse your mouth with water or mouthwash – you’re washing away the fluoride! It can be tough to break the habit, but doing so can reduce tooth decay by up to 25%."

So there you have it, you've been warned!

Luckily, it’s not too hard to adjust — it’s just a matter of remembering not to rinse your mouth under the tap, especially in those groggy moments after brushing.