How Often Should You Wash Your Water Bottle?

Taking a reusable water bottle wherever you go, whether it’s to the office, the gym, a pilates class, a walk around town, or on a hike, is handy and ensures you stay hydrated. Whether you fill your bottle with water or other beverages, like tea, coffee, or flavored drinks, you’ll want to make sure to regularly clean it throughout the week. Cleaning often will minimize any build up of germs in your bottle. “The high moisture content inside bottles readily breeds mold and bacteria, which can influence the taste and quality of the water over time,” says Bryan Quoc Le, Ph.D, food scientist and author of "150 Food Science Questions Answered. So if you’re not washing your reusable bottle frequently, you’re not cleaning it enough.

How Frequently Water Bottles Should Be Cleaned?

The answer of how often you should be washing your water bottle may surprise you. If you’re not washing your bottle daily, you’ll want to start cleaning it after each use. “Reusable water bottles should be washed once per day with soap and hot water,” says Le. Washing daily is important to reduce microorganisms from calling your water bottle home. “Bacteria replicate quickly and could form biofilms on the surface of the bottle,” says Dr. Tzeng. “A daily cleaning of bottles can reduce the bacterial population.” 

And experts agree that you should sanitize bottles once a week. “It is recommended to clean the reusable water bottles daily and sanitize them weekly, especially if the bottles are used to store contents that contain nutrients (sugar beverages) and at warmer temperatures (coffee and tea), which support growth of microorganisms,” says Dr. Zheng.  

There are other considerations that will influence regular cleaning. “If you’re sick, or eating while using the water bottle, it should be washed in-between uses,” says Tonya Harris, award-winning toxin expert and author of The Slightly Greener Method. 

Does The Material Of The Water Bottle Make A Difference?

There are a plethora of water bottle options, including plastic, aluminum, stainless steel, and glass.  The material can influence how well bacteria and mold attach and grow on a surface. “Microorganisms attach to surfaces with different efficiency due to the surface roughness (surface area) and other surface properties,” explains Dr. Jeremy Tzeng, Associate Professor, Department of Biological Sciences, Clemson University. “It has been reported that microorganisms attach less effectively to stainless steel 2 and glass, but attach more effectively to aluminum and plastic.”  

Not only is glass more difficult for microorganisms to attach to, you can also see inside the water bottle. “Glass is very transparent, so it's easier to see if there's any need to clean the bottle by visible inspection,” says Le. If you have a plastic water bottle, there can be more areas for microorganisms to lurk. “Plastic is prone to forming little cracks and grooves and therefore provides more places for microbes to grow,” explains Justine Dees, PhD, Founder of Joyful Microbe.

The Best Way To Clean Water Bottles

Now that you know it’s best to clean your bottle every day, you’re likely wondering what is the best way to clean your water bottle?

Cleaning your water bottle is a simple and straightforward task. You’ll just need hot water and soap. “Soap is a detergent that disrupts cellular membrane integrity and causes lysis of bacterial cells and vegetative (growing) yeasts and fungi,” explains Le. “Hot water facilitates the disruption of lipid cellular membrane with soap.” Some people may use bleach but Dees shares that using bleach on your water bottle isn’t necessary since microbes will be removed with hot water and soap. 

How To Clean The Water Bottle

Harris breaks down the method in five simple steps:

1. Start by unscrewing the lid, and removing any parts that can separate – the straw, any valves, etc. that are meant to be removed to clean,” she says. A sponge may not reach the bottom, especially if it’s a big or narrow bottle so you’ll want to use a long brush.
2. Use a clean bottle brush to thoroughly scrub the inside walls of the bottle, making sure to reach the bottom, with the soapy water.
3. Use a smaller straw brush to get the interior of the straw, and to help scrub the tiny crevices around the lid if needed.
4. Rinse the top and bottle well with warm water until it runs clear. 
5. Be sure to let the components dry completely. Set the bottle, lid, and straw upside-down on a clean dish towel or paper towel so the components can dry overnight. 
   

How To Clean The Straw

Two easy steps to clean the straw, according to Harris:

1. Run warm water through the straw, then add a small amount of dish soap to the brush, and scrub the inside of the straw. 
2. Follow by running warm water through the straw until it runs clear.
   

How To Clean Valve Or Flip-Top Bottle

Cleaning advice if you have a valve or flip-top bottle, according to Harris:

1. Open the valve and run warm water through the valve and clean the same way you do with the straw. 
2. Use a soapy bottle brush to scrub the inside of the valve, then run warm water through it to rinse. 
3. Leave the valve or flip-top open to dry completely.

The Best Ways To Sanitize Your Water Bottle

Sanitizing your water bottles weekly is recommended. There are a few effective ways to sanitize. “If the bottle is dishwasher-safe, place it in the dishwasher so the heat setting at the end can sanitize the bottle and lid,” shares Harris. “I like to clean and sanitize the brushes also, by throwing them into the dishwasher, where the heat can sanitize them,” she says.

You can also use white vinegar after cleaning the bottle with soap and warm water. “Then fill the bottle with a 50/50 combo of warm water and white vinegar [and] put the lid on and give it a little shake, remove the lid, then leave it to sit overnight,” explains Harris. “In the morning, wash with warm soapy water as usual and rinse.”

A third possibility for sanitizing a water bottle is to use hydrogen peroxide, especially if the water bottle has a slimy film. “Simply wash the bottle, then fill the bottle about a quarter of the way up with hydrogen peroxide, put the lid on, and give the bottle a gentle shake,” says Harris. “Remove the lid, and let the hydrogen peroxide sit for 10 minutes and rinse and clean well.” Dr. Tzeng adds, “Hydrogen peroxide has good compatibility with stainless steel and aluminum and can be used for their cleaning.”

What Bacteria And Mold Can Grow?

Bacteria and microorganisms can easily grow in a damp reusable bottle. If you use your water bottle for flavored drinks or a beverage with sugar, you’ll want to be proactive with cleaning. “Depending on what types of additives are added to the water, such as flavorings, soda, or sugar, a large variety of microorganisms can grow,” shares Le. 

There are different types of molds and bacterias that may love living in your bottle. “Molds such as Aspergillus, Cladosporium, and Penicillium species can grow and produce mycotoxins that can cause illness,” says Le. “Yeast, lactic acid bacteria, Escherichia coli, and Pseudomonas bacteria have all been found in water bottles. Pathogenic bacteria such as Escherichia coli and Pseudomonas aeruginosa can cause food poisoning and gastrointestinal illness,” he says.

Can You Get Sick From An Unclean Water Bottle?

Wondering what the likelihood of getting sick from a not so clean or regularly cleaned water bottle is? Good question. Typically, our immune systems will fend off any issues. “If you have a properly functioning immune system and you don’t clean your water bottle on a perfect daily schedule, it’s likely nothing will happen to you that you are aware of, says Dees. Le agrees, “Most of the microorganisms and fungi associated with reusable water bottles could be effectively dealt with by an individual’s immune system without causing problems.”  

So there isn’t much need to worry but make sure you’re cleaning your bottle after every use. But if your water bottle becomes a feeding ground for mold and bacteria, you could be more at risk for becoming ill. “When the number of microorganisms and fungi becomes high, or when an individual is immunocompromised, they can cause illnesses,” explains Dr. Tzeng.

Before you start squirming at the thought of so many potential germs and microbes potentially hanging around in your reusable bottle, just relax. Dees understands that microorganisms may make people uneasy. “It can be scary to think about the possibility of germs growing in your water bottle,” she says. But don’t panic. “Microbes are everywhere, and that’s actually totally fine,” explains Dees.  “Most are harmless, and many can even be helpful, like those in your microbiome, fermented foods, and probiotics, among many others.”