Reusable water bottles are beneficial in so many ways. Helping keep you hydrated, they also cut down on single-use plastic, and save you money every time you refill instead of buying a new bottle of water. Plus, with all the chic stainless steel flasks and glass bottles on the market – not to mention sporty carrying straps – they’ve become something of a fashion accessory. Trying to hit the NHS-recommended eight glasses of water a day for adults is an excellent idea, of course, but did you know there’s one way your refillable bottle could potentially be detrimental to your health? According to a study from waterfilterguru.com, reusable water bottles contain an average of 20.8m colony-forming units (CFUs) of bacteria, which equates to 40,000 times more than the microbes on a toilet seat. So what might be the consequences if you continuously sip and refill without washing your bottle properly between uses? We asked health experts to talk through the risks… Bottling up bacteria “A common misconception when it comes to reusable water bottle hygiene is that as you’re typically filling it with pure water and it’s only coming into contact with your own mouth, there’s little need to clean it often,” says Dr Donald Grant, senior clinician at The Independent Pharmacy. However, every time you drink from the bottle, you’re transferring bacteria from your mouth, which can then multiply in the container. “Anything that is reusable can be prone to accumulating dirt, dust or debris and, as a result, bacteria,” says private GP Dr Suhail Hussain. “This is exacerbated by the fact water bottles are the ideal environment for harbouring bacteria due to being moist.” Hard to reach crevices – for example, inside a screw top or under a flip-up straw – could also develop mould, and then there’s contamination from other sources. “When you store it in a gym bag, for instance, it can pick up bacteria from the interior of the bag or anything else stored in it, while you can also transfer bacteria from your hands to your bottle,” says Grant. “If your bottle has a valve cap, you may need to lift or twist it with your fingers, and this can transfer bacteria you may have picked up from touching other objects or surfaces.” What types of microbes are found in water bottles? “These might be simple commensals such as streptococcus and staphylococcus, which normally live in symbiosis with their host (i.e. us) but can become problematic if they accumulate, or the individual is under the weather,” Hussain says.“Bacteria such as E. coli – a common cause of urine and bowel infections – can often colonise the water bottle following repeated handling, such as taking the cap on and off.” These bacteria can potentially cause a variety of issues. “You may become sick and develop gastric illness, such as diarrhoea or vomiting,” Hussain continues. “Gram negative rods – another common bacterium found in unwashed bottles – can lead to urogenital tract infections and pneumonia.” Grant warns: “If there’s a build-up of mould inside the bottle, this can cause allergy symptoms, such as a runny nose, sneezing, or red and itchy eyes. Symptoms might be more severe for someone with asthma.” How often should you wash your reusable water bottle? “To minimise your risk of getting sick, you should ideally clean your water bottle after each use,” Grant says. “As a minimum, you should aim to wash it thoroughly at least a few times a week.” Hot water and washing up liquid are all you need to banish bacteria on the daily. “Fill the bottle with hot soapy mixture and swill around, or leave to soak in a detergent mixture,” Hussain advises. “Remember to pay special attention to lids/caps and screw top regions – use a clean brush [to scrub them].” If you’ve neglected your bottle for a few days and it needs a deeper clean, Grant suggests: “Soak your bottle overnight in a solution of half vinegar and half water. Rinse the bottle and let it dry fully before using it again.” Storage is also important to help minimise nasty microbes. “Where possible, you should keep your water bottle out of germ-rich environments such as your gym locker or sports bag,” Grant says. “You should also avoid filling your bottle with anything other than water, such as protein shakes, energy drinks, or sugar-rich liquids, as sugar can stimulate the growth of bacteria.” Hussain adds: “Don’t leave water bottle in the sun for long periods of time or siting in the cup holder in the car – the mixture of warmth and moisture is likely to make bacterial overgrowth worse.” Read More Charity boss speaks out over ‘traumatic’ encounter with royal aide Ukraine war’s heaviest fight rages in east - follow live Prince George visits Eton with parents Prince William and Kate Middleton King Charles and Queen Camilla ecstatic after getting their first Royal Ascot winner As Elon Musk calls cis ‘a slur’ – what does the term cisgender actually mean?

Defining Dishes is an IndyEats column that explores the significance of food at key moments in our lives. From recipes that have been passed down for generations, to flavours that hold a special place in our hearts, food shapes every part of our lives in ways we might not have ever imagined. There is a family scene I would love to engrave into my memory that involves my father, myself and my son, all making prawn wontons in one kitchen. Prawn wontons are so simple, like all good dishes, and they have a really special place in my heart. I have very fond memories of making them with my father, who is from Hong Kong, when I was growing up and it is my favourite dish. Now, it’s my five-year-old son’s favourite dish as well and he’s the same age I was when I first started making prawn wontons with my father, so it makes me excited to share the dish with him. When my son was younger, his Ye Ye (grandfather) would bring homemade wontons whenever he came over to my house in Peckham. But just recently, we were over at my parents’ home, and he made his first wonton. We were all very proud! It’s so nice because it’s a dish that has run right through my family, it was brought and championed here by my dad. He moved here in 1975 and has the classic first-generation immigrant story. He worked three jobs, moved around a lot, saved money and opened his first restaurant in 1985, 10 years after arriving in England. He finally retired in 2017, but he couldn’t get away from my restaurants. I opened my own establishment, Mr Bao in Peckham in 2016, and then Daddy Bao in my father’s honour. Even now when he comes around to visit, I make him talk more about restaurants. I think he enjoys it, though, and it reminds him of home. That’s really important now because ever since the 2019-2020 mass protests in Hong Kong, the country is a sad place at the moment if you’re from there. But it’s still an amazing place. My favourite part about making wontons from scratch was always the time spent with my dad. The chit chat between us, me kneeling on a stool and him standing at the counter. My hands were not as dextrous at that age and I certainly wasn’t practised, but he would be there to help show the right way to make the little parcels and finish them up for me. The bonding moment is what I cherish the most. Mum is English and she got involved too, she is actually amazing at it. Prawn wontons are also part of Christmas time for my family. Our big tradition is to have a massive steamboat on Boxing Day, which most people of Chinese descent will be familiar with. It usually involves a big, steaming pot of soup on a constant boil, and everyone sits around the table cooking fresh, raw ingredients in it and eating as they go. Prawn wontons are a big, big part of that meal for us, especially now that we have a couple of young kids running around at Christmas time, they really love it. The thing I remember most about making wontons with Dad is the filling. He has his own method for making the prawn mince that goes inside the parcels. He gets his prawns and chops them up, mixes them with any additional ingredients like garlic, and then he would make me pick up a handful of the mixture and throw it back down onto the chopping board, pick it up and throw it back down. It somehow aerates the mince and softens it, and makes it stickier so there aren’t big chunks of prawns floating around. I haven’t really adapted Dad’s recipe for myself, aside from the type of dipping sauce I like to have with them. We keep it very traditional. Oh, I suppose I do have a slight modification, actually. I like to mix gambas (white) prawns from the southwest coast of Spain with North Atlantic shrimps, which are tiny, tiny little crustaceans the size of your nail. They have got a really good flavour. I like to chop those up into the mince with the bigger prawns, add a bit of salt and white pepper, stir it through and then do the throwing method as my dad does. We usually make our own wonton skins. In a pinch, we’ll use shop-bought ones, but when we know we’ve got time we’ll make our own. At the moment, Dad makes handmade dumplings with my sister for her business so they have a dumpling skins machine – but we used to make them by hand, old-school style. He would roll them out because he could get the thickness of the skins right. It wasn’t possible when I was young as I had no idea and was clumsy! They have to be thin, but not so thin that they break or the wontons will open up in the water. It’s something I haven’t managed to master, but there’s still time. Some places don’t even use the regular wonton skins, and they are still amazing. One of my favourite restaurants ever was in Hong Kong – it has closed down now – but it was a hole-in-the-wall type of place that served two types of wontons: classic wontons or fish skin wontons. That was their entire menu. They used fish skins instead of pastry skins to wrap their wontons, and they were something like £1.20 for a bowl at the time. It was definitely the best meal I had with Mum, Dad and my sisters in Hong Kong. The wontons get boiled for two minutes. You can make a wonton soup with a base stock, using ginger, spring onions, salt, pork bones. Boil that down and skim off the top. Or, you can dip the wontons into a chili garlic sauce, which is how my dad likes – although another way I differ from Dad is that I like to add black vinegar to the sauce of soy sauce, garlic and chili, to add an extra layer of acid. You can also eat them as they are, they are completely delicious. My stomach is rumbling as I think about them. As my son gets older, it will be really nice to be able to make wontons altogether, the three generations of us at the kitchen island, chatting away. That’s what I’d like my son to take away from those sessions, the memory of doing it with his Ye Ye and me. I’d also like him to, in time, be able to link quality to food and what you’re putting in your body. I want him to understand that even though it’s so easy to go to the shop and buy something, everything starts out as a living thing. A prawn is an animal and a chive is a real plant grown in the soil. You don’t have to make it yourself and you should go to restaurants to support them, but when you do go, you’ll have a better appreciation for it. Frank Yeung is the chef-owner of Mr Bao and Daddy Bao in London. 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