We should be replacing the water in fish tanks every week. “Fish health is directly linked to water quality, so it’s important to keep on top of tank maintenance. Each week you should use a gravel scoop to remove 10-20 per cent of your aquarium’s water and replace it with dechlorinated water,” advises Dr Karlien Heyrman, a vet at Pets at Home.

Cloths are used on a daily basis, which means they can quickly become a breeding ground for germs and bacteria. “We should be washing cleaning cloths after every use, and switching them out every four weeks,” advises cleaning guru Danielle Mason. “You should always have a different cleaning cloth for each section of the house. Washing up brushes should be replaced every four weeks.”

“It may be surprising, but ice cubes trays need a little maintenance to keep them germ-free,” says cleaning expert at Property Rescue, Emily Barron. “Clean your ice cube trays regularly to remove any debris and replace the water every month to prevent the cubes turning cloudy.”

“This depends on whether you’ve got pets, as dog or cat hair can block up filters a lot quicker,” advises Mason. “I would say change your filter every three months because dust mites can live in there and bad smells can also build up.”

Our eye area is a breeding ground for bacteria, and so mascara should be replaced regularly. “You should change your mascara every three months,” says skincare expert and founder of Skin Rocks Caroline Hirons. “If you’re using an expired product, you could be exposing yourself to bacteria.”

It’s important to regularly clean your make-up brushes to avoid the build up of bacteria and product residue, but how often should we be replacing them? “If like most people you use your brushes every day, you need to replace them more frequently than if you only use them occasionally,” says Natalie Yorke, founder of helloskin.

“In some cases, the higher the quality of the brush, the longer they may last. As a rule, you should replace your makeup brushes every three to six months. However, if you have had any eye infection or skin conditions, it’s a good idea to replace your brushes to avoid re-infection.”

Many of us may use the same toothbrush for months, but this can be damaging to our dental health, says Dr Sam Jethwa, founder of Bespoke Smile and vice president of the British Academy of Cosmetic Dentistry.

“I’d advise changing your toothbrush, or the head to your electric toothbrush, every three to four months,” says Dr Jethwa. “If your bristles are splaying, looking worn out or feeling less stiff, then you should change it as it won’t be cleaning your teeth and gums effectively. Change your toothbrush sooner if you’ve been unwell to avoid harbouring germs.”

If you do choose to replace your toothbrush regularly, then picking up an eco-friendly option – such as a bamboo toothbrush – can go a long way in helping the environment.

There is a lot of debate about how often to change your passwords on social media, email and finance accounts. Some experts say every 90 days, and other experts think this is counterproductive.

One thing is certain: Change your password immediately if you discover there has been a data breach.

“It’s best to replace plastic pet bowls every few months to avoid bacteria build-up. However, ceramic and stainless-steel bowls can last a lifetime if cared for properly as they are non-porous and much easier to sanitize,” advises Dr Heyrman.

“Always clean your pet’s food and water bowls after every meal, and remember to wash them separately from yours – even if using a dishwasher – to minimise the spread of bugs.”

“People are so unaware that you should clean your hairbrush often,” says Mason. “Pull the hair out and leave to soak in bicarbonate of soda at least once a month, and then replace every six months. This prevents bacteria and oil build-up on the teeth and ensures your hair doesn’t get greasy between washes.”

Sunscreens tend to have the shortest PAO (period after opening) of all skincare products. Due to its importance in protecting our skin from harmful UV rays it’s essential to keep an eye on when the product is going out of date. “You can find the PAO inside the small jar symbol on SPF bottles,” explains Hirons. “You should be using two finger lengths of SPF daily (rain or shine), so it’s unlikely you will surpass this. However, if you continue to use SPF after this date then the protection properties deteriorate.”

“Moisturisers also have a PAO that you should pay attention to,” adds Hirons. “Once opened, most face moisturisers tend to have six months, but check the packaging.”

As a general rule, experts suggest changing your engine oil every 3,000-5,000 miles or approximately every six months. Depending on your car’s age, oil type and driving conditions, you may be able to change the oil every 7,500-10,000 miles, but it’s best to check your owner’s manual to see the manufacturer recommendations.

Even with gentle usage and care, all bras lose their shape over time. In fact, experts recommend replacing bras every six months – or after about 180 wears. “If you have a large selection of bras in rotation, you can go longer than six months before replacing, especially if you’re caring for those bras properly,” says Ali Cudby, author of Fit My Bras and founder of Fab Foundations. “Putting your bras in the dryer breaks down the elastic much more quickly, so save bras from an untimely death by letting them air dry and hand wash when possible.”

It’s generally accepted that the standard life-span of gym or running trainers is somewhere between 300 and 500 miles, and lightweight shoes tend to be somewhere between 250 and 300 miles. If you’re running 20 miles per week, you’ll probably need to replace them after four to six months, advises Runners Need. However, if you’re less active then you can wait longer – or at least until they start to smell.

Perhaps the most disgusting part of every bathroom, toilet brushes can be a serious health hazard if you aren’t keeping them cleanly. Henry Paterson, senior operations executive at Housekeep, advises replacing them every six months, while Aggie MacKenzie says they’re not necessary at all. “There should be a law against toilet brushes,” says MacKenzie, from Channel 4’s How Clean is Your House? and author of The Miracle of Vinegar. “Just use bleach and toilet paper instead.”

“Shower curtains can get really grotty, especially in bathrooms that aren’t ventilated,” says MacKenzie. “If you’ve got a cheap one and it doesn’t cost much to replace, I’d suggest throwing them away as soon as they’re starting to look grubby or mouldy, which can be after six months. But you can wash these in the washing machine to make them last longer.”

Shower heads can be a hotbed of germs. A study by the University of Colorado Boulder found that the warm and wet conditions lead shower heads to develop a collection of bacteria and fungi, known as biofilm. Then every time we shower, the hot water disperses this scum into the air. For this reason, it’s recommended to replace your shower head every six to eight months. However, they can last a lot longer with regular cleaning.

“The marks from knives can cause bacteria to deepen into the chopping board and could potentially lead to contamination of food, which can be harmful when preparing meats and fish,” says interiors expert Nick Shacklock. “We’d advise replacing every year.”

Research shows that our mobile devices can be as dirty as a toilet seat, in particular the front screens. Many people buy a cover for the front to prevent the screen from being damaged, but this can accumulate tons of bacteria from the constant typing and swiping, which is why it’s recommended to replace them once a year.

Cat owners know how important it is to maintain their pets’ litter tray, as some cats may refuse to use it otherwise. But how often should we be replacing the tray? “Litter trays should be spot-cleaned daily and once a week you should replace the litter and clean out the tray with hot water and mild detergent,” says Dr Heyrman. “It’s best to replace a plastic litter box once a year, or sooner if you notice it is stained.”

“Using your pillow every night leads to a build-up of dead skin cells, sweat, oils, saliva, make-up and allergens, so you should replace them every one to two years,” explains sleep expert for furniture company And So To Bed, Dr Lindsay Browning. “Not replacing often enough can also cause neck pain due to a lack of support. You’ll know you need to replace your pillow when it is flat or lumpy, or smells and has stains.”

Smoke alarms can save lives, which is why it’s so important to keep them in the best condition possible. The London Fire Brigade advise changing the battery every 12 months in a standard smoke alarm. “Smoke alarm sensors degrade over time, leading to a reduced sensitivity in detecting heat or smoke,” added a spokesperson. “We would advise buying a smoke alarm with a 10-year, or long-lasting sealed battery with a British Standards or European safety mark.”

According to Healthline, dried herbs typically last one to three years, while ground or powdered spices will expire in two to three years. Whole spices have the longest shelf life, lasting up to four years. Refreshing them within their expiration date is key to maintaining the quality, taste and health benefits.

Over-the-counter medications such as antihistamines, paracetamol and ibuprofen can be found languishing in cabinets and first aid kits for months on end, but they do have a use by date. “I would advise people to replace their over-the-counter medications as they come up to their use by date, which is usually around one year,” advises Dr Claire Ashley. “It might be helpful to put a reminder in your calendar to double check your medications periodically and don’t take anything that has expired.”

If these handy tubs aren’t cleaned and maintained they can be a breeding ground for bacteria. “Get into the habit of replacing your Tupperware every few years – and more often if it’s used frequently or is used to store strong, acidic content,” says Barron.

“Bath mats are a surprisingly dirty part of bathrooms,” explains MacKenzie. “They’re touching soggy feet as well as the bathroom floor and collecting all the wash off from your body when you get in the shower.” As such, experts suggest you replace them every two years.

Although we mainly use them once we’re clean, towels pick up a lot of excess dirt. Paterson advises you switch them out for new ones every one to three years.

While the humble kettle is a kitchen essential, it can, over time, gather dirt, limescale and rust which can affect its performance, ruin the taste of your daily cuppa and even affect your health. “It’s a good idea to replace your kettle every few years, or before if it’s showing signs of wear and tear, or heavy limescale build-up,” advises Gene Fitzgerald, hard water expert from BOS. “Don’t leave water sitting in it for more than a couple of days, and clean the inside once a week.”

“Plastic water bottles can start to break down after continued use and need to be replaced about once a year,” says Leanne Stapf, chief operating officer at The Cleaning Authority. “Stainless steel bottles generally only need to be replaced due to wear and tear.”

“This depends how you treat your carpet and how many people you have in and out of your house,” explains Mason. “Our shoes carry so much bacteria, dirt and germs, so it’s a good idea never to wear shoes in the house. I shampoo my carpets once every six months and change them every five years.”

“As long as you keep your toilet bleached, cleaned and sanitised on a regular basis they can last five years,” says Mason. “My cleaning advice would be to use anti-bac wipes so they can be thrown away.”

“The average duvet should last five years if it’s properly cared for and washed every six months so that stains and odours are removed,” says Rex Isap, CEO of Happy Beds. “Keeping a duvet for too long can cause sweat and dust mites to build up, as well as dead skin – each night the average person loses around 300,000 dead skin cells.”

“Providing you clean and care for them properly you should be able to get five years usage out of non-stick pans,” says Mason. “Avoid using harsh scourers which can scratch it – if there is stubborn dirt in a pan, soak it for a few hours before cleaning it.”

A cycling helmet is generally good for around five years, advises Cycles UK. “Of course, you should also change your helmet if you have a crash or even a small tumble because this could compromise the helmet’s performance,” they added.

“Most guidance suggests that mattresses should be changed every eight years,” says Hannah Shore, sleep expert at Silentnight. “However, materials used now mean some can last longer. Spring mattresses last better.”

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