You may think that cleaning your reusable water bottle once a week, or even just once a month, is enough. After all, it looks perfectly clean and you only fill it with water. But how often should you be cleaning something you drink from each day? As it turns out, moist environments like a water bottle are the perfect breeding grounds for bacteria. (Fair warning: When you take a look at these numbers, you may feel compelled to chuck out your old water bottle and start anew.) Based on an analysis from the environmental testing firm EmLab P&K, the average reusable water bottle has over 300,000 CFUs (that is, bacteria colony-forming units). That equates to roughly six times the amount of bacteria found on pet bowls.
We spoke with Dr. Dewan Farhana, founder of cleaning professional marketplace Betternest, to get her take on this research—she backed it up and compared this amount of CFUs to the amount found on public toilet seats, too. "A high percentage of the bacteria present are gram-negative rods, such as E. coli, and can cause various illnesses," Dr. Farhana explains. "What's not thirst quenching is that the area your lips touch on the slide-top bottles has one of the highest CFUs at over 900,000 square centimeters!"
Choosing a Hygienic Reusable Water Bottle
Needless to say, these numbers are pretty frightening—even if you're not a total germaphobe. To help you find the most hygienic design—and one that will be easy to care for—Dr. Farhana suggests these tips when choosing your next reusable water bottle: Pick a straw-top water bottle over other design types (this is the easiest to care for), and avoid purchasing a slide-top option as its design has the highest potential for bacteria build-up. It shouldn't have too many crevices or tough-to-clean areas. Plus, opt for stainless steel, metal, or glass instead of plastic since it's more difficult for bacteria to grow on smoother surfaces.
How Often to Clean
No matter what type of reusable water bottle you choose, its state of hygiene is only as good as how thoroughly and frequently you clean it. "Like dinner plates, coffee cups, and drinking glasses, you should clean your reusable water bottles regularly, and ideally daily if used every day," says Sean Parry, cleaning expert at Neat Services. "Bacteria thrive in warm, dark, and moist environments, so any traces of water in the bottle and around the drinking nozzle are prime breeding grounds for bacterial growth. For example, you wouldn't expect to use the same coffee cup for a week without cleaning it."
How to Clean
When it comes to cleaning your reusable water bottle, a wash at the end of the day is recommended. Sean Parry recommends three different methods. Soap and water: Use a bowl of warm water and soap to rinse both the inside and outside of your water bottle, making sure you brush within all the nooks and crevices around the drinking nozzle, then leave it to air dry overnight. White wine vinegar: Fill your water bottle a fifth of the way with white wine vinegar and the rest with hot water. Leave it overnight, then rinse thoroughly the following morning and leave to air dry. (White wine vinegar is a great eco-friendly product with disinfectant properties, so is a very effective option.) Dishwasher: This is probably the easiest option. (Make sure to check the bottle's label to ensure that it's dishwasher safe!) Let the bottle air dry before using again.