While reusable water bottles are great for the environment, they almost always end up looking pretty disgusting inside.
If you haven't peeked inside your water bottle recently, you may want to take a quick squiz, particularly if you're not one to give it a thorough clean.
If you spotted black grime and mould and have struggled to remove it, a decluttering expert has shared the ultimate cleaning method.
Anita Birges, from Sydney, who is also known for her handy organising and cleaning hacks, shared a TikTok revealing rice, dishwashing liquid and water are the key ingredients to get your bottle squeaky clean from the inside.
"How often do you check the inside of your stainless steel water bottles?" she asked viewers.
"You'd be surprised and shocked at the amount of mould that can build up inside.
"Take a look, it's really quite gross. But how are you supposed to get inside? It's such an awkward place, especially if you don't have a bottle brush. Well have I got the ultimate cleaning hack for you."
Anita demonstrates by first pouring half a cup of uncooked rice into the water bottle.
She then squeezes a small amount of dishwashing liquid into it and tops it up with half a cup of water.
"Put the lid on and shake, shake, shake … It's that simple and easy," she said.
Anita, who is the founder of Mise en Place, then grabs a sieve and pours the contents on top to catch the rice.
"Rinse thoroughly. Spotless clean water bottle. No mould," Anita added as she showed the camera the clean bottle.
The clip titled, "Water bottle cleaning hack every person should know" has been hugely popular, being viewed more than 57,000 times.
Thousands have jumped in the comments section branding her method "genius".
"Amazing will give this a go," one viewer wrote.
"Genius. Shared with my 24-year-old daughter who never cleans her water bottle," wrote another, while another simply added "great idea".
Others revealed the shock they got when they looked inside their bottle.
"Legit every time I use it I look inside them … how'd it even get that bad?!" one TikTok user commented.
"Mine was so gross and I was about to throw out. Now thanks to you – it's clean," said another.
Others who tried the hack also added it "worked so well".
"Nice one! Never seen that hack before," one person said.
Some couldn't see past "wasting" rice and said they would rather clean their bottle with the help of utensils.
"I use a washing cloth and use a knife or fork to squish the cloth into the corners, then rinse thoroughly. Your way looks good too, but then I'd have to chuck out the rice," one person wrote.