Leaking water bottles, pen ink, the rotting juice from an old banana, school backpacks and lunch boxes can get pretty grotty.
Western Sydney mother-of-two Minakshi Gajera has cleaned all kinds of stains and spills in her children's school bags and fabric lunch boxes.
The home cleaning enthusiast and content creator from Dharawal lands says she likes to give them a thorough clean at the end of each term.
"It's like full of crumbs, sticky wrappers and God knows the mysterious stains in it, they even smell bad," she says.
Here's some expert advice on the best and easiest way to clean backpacks and fabric lunch boxes so they're ready for when school returns.
Read the bag's label
This is the first step before cleaning any materials, according to textiles expert Dr Rebecca Van Amber from RMIT's School of Fashion and Textiles in Melbourne, on Taungurung lands.
"You don't always know what the bag is made of, so it's definitely best to have a look and see what the manufacturer's instructions are," she says.
"There might be materials in the bag that shouldn't be dry cleaned, or maybe they shouldn't be submerged or soaked, that sort of thing.
"If you have a bag that has any sort of smart capabilities, that means it probably has some electronic components and you definitely don't want those to get wet."
She says if you are in any doubt, you can contact the manufacturer to see what they recommend.
Can I use a washing machine?
Our experts say this method can be OK, but it is not recommended for all types of bags or washing machines.
"Sometimes backpacks have internal frames," says Dr Van Amber. "You wouldn't want to put anything like that in your washing machine."
"[But] I put makeup bags and things through my washing machine all the time, because they're small, they're soft, they're pretty much fabric."
"Especially if it's like an old school sort of canvas backpack or something that's maybe a lightweight nylon backpack.
"They're very much in that textile category and I think those will be fine to put through your washing machine."
But she says to avoid using washing machines with a central agitator as that may damage the bag.
Minakshi starts by emptying the bag completely, removing any tags or key rings and giving it a good shake to get rid of dust and crumbs.
"I put it inside a pillowcase or laundry bag and then wash it on a gentle or delicate cycle," she says.
Dr Van Amber says any regular laundry detergent is fine, but you could opt for detergent designed specifically for sports clothes.
"Something that would be suitable for like your athletic wear, is going to be probably suitable for your backpack as well because they're essentially made out of the same types of materials," she says.
How do I hand wash and remove stains?
Brisbane mother Susie Myers designs and develops schoolbags and lunch boxes for a living.
She recommends starting with a small vacuum cleaner to get out any built-up dirt or crumbs in the bags before washing.
"On our backpacks, we have care labels which specify sponge cleaning and on our lunch bags we say machine washable," she says,
For sponge cleaning she suggests "using a damp cloth, a bit of mild detergent or soap in water and doing a spot clean".
"That means just getting in where there's any heavy use areas like … straps and the bottom of the bags or internally giving it really good wipe out," she says.
She recommends wiping out insulated, fabric lunch boxes every day and giving them a heavier clean in the washing machine every three weeks.
Dr Van Amber says hand washing is a good method for most types of bags and lunch boxes.
"I would probably be soaking it in my bathtub (or laundry tub) with a bit of regular laundry detergent for a couple of hours," she says.
"Then give it a rinse and let it dry outside."
If it needs more than that, she suggests using a soft brush on it after soaking, rinsing then repeating the process with fresh water.
Ms Myers says for mould prevention and mould stains; you can also add a cup of white vinegar into the wash itself.
If there are ink or other stains Dr Van Amber says you can use a laundry stain removal stick and a toothbrush.
"Like you would do with clothing if you had a really difficult stain on an item."
Be cautious of scrubbing screen-printed images or logos, as you risk removing them.
How do I dry the bags?
Once washed, Dr Van Amber says it is best to let bags dry outside.
"Line drying outside is definitely the best way to go," she says.
"If it's not in your washing machine and going through a spin cycle, it's going to be really saturated with water."
She says the dryer and iron should be avoided as "bags are often made of synthetic materials that will melt".
Ms Myers says making sure bags dry completely is important.
"You've really got to make sure that there's a lot of ventilation [and] you're getting the internal parts as dry as the external parts, because any moisture is going to cause potential growth of mould."
