Key Takeaways
- Daily water bottles or hydro flasks need daily cleansing.
- Other water containers like tea kettles, 5-gallon jugs, hiking hydration packs, and filtered drinking containers need weekly sanitization.
- Your bottle — yes, the one you’re putting your lips to today — could carry harmful levels of bacteria, including E. coli.
As I published this article, I have my teenage son‘s hydro flask, my tea kettle, my Nespresso water container, and the aluminum water bottle I bought at my local whole-food store that I’ve been refilling for months all in the sink with soap, a dollop of bleach, and warm water. I’ll be scrubbing them all soon. And I will remember to let them completely dry before using!
We all know it’s crucial to stay hydrated (read more on how much water you should be drinking) and it’s common these days to see people toting reusable water bottles everywhere they go.
A typical handheld reusable water bottle is between 24 and 32 ounces, and if you’re like me, you’re filling that sucker up 3 to 4 times daily. Multiply that by 7 days per week, and it’s bound to need a good wash in there somewhere. But how often and how deeply do we need to clean them?
Read on, and you’ll find out. Suffice it to say:
That odd but ignorable smell in your empty bottle — that’s bacteria. Strange tastes you try to overlook — that’s bacteria. The slick or slimy feeling on the straw inside the bottle or container is not an anti-stick solution — that’s bacteria.
If you’re one of those people who believe us when we tell you and don’t need to know all the nitty-gritty, skip ahead to the products and cleaning strats we recommend. If you’re “dubious at best,” click below for data and proof.
You may have heard that reusable water bottles can have 40,000 times more colony-forming units (CFUs) of bacteria than a toilet seat. The study behind those stats was carried out by a consumer organization whose research is not peer-reviewed, however there are multiple scientific studies that confirm the presence of high (even alarming) amounts of bacteria in reusable bottles.
Researchers at Purdue University conducted tests of 90 bottles in 2017 and discovered that over half (60 percent) were contaminated at a level that exceeded safety standards.
Another 2017 study of rapid microbial growth in reusable drinking water bottles found 34,000 bacterium per milliliter (mL) in kids’ water bottles and 75,000 bacteria counts per mL in adult water bottles.
If you’re an exercise enthusiast, sweat and germs from your workout venue and hands only compound bacteria.
E. coli and Staphylococcus aureus are two of the main offenders of more concerning bacteria that multiply over time and heat.
Dr. Yuriko Fukuta, an associate professor and internist in Houston, was interviewed by Baylor College of Medicine and says germs can multiply inside your water bottle if not cleansed after each use.
Ask yourself, have you experienced unexplained:
- headache
- sneezing (an allergy symptom if mold particles are in the bottle)
- stomach upset or nausea
If so, washing your water bottle to rule out that as a cause might be a helpful first step.
Yes. Even if you only drink water in your hydro flask, or jug, bacteria transferred from your lips, backwash, or just warmth can make bacteria particles multiply.
Dr. Fukata says metal or glass are more sanitary than plastic reusable water bottles and, that water bottle you keep refilled in your car (🙋🏽♀️Guilty!) is a bad idea, as the warmth inside a parked car can accelerate germ festering.
If you don’t wash your water bottle, bacteria will grow. Period.
In an early 2000s cross-sectional observational study with more than 75 elementary students who had their their reusable water washed intermittently between uses — or unwashed for months — fecal contamination evidence was found.
Drinking water thresholds were not met in 64% of the tested bottles, while more than 13% had fecal bacteria or gut bacteria (coliform) that usually increases to fight fecal bacteria ingested.
Significant regrowth of bacteria was demonstrated in treated drinking water (think: water fountain filling stations or tap water) when left at even room temperature, for as soon as 8 up to 24 hours.
A 2018 cross-sectional study observed just under 30 participants with regularly used stainless steel water bottles compared to a brand new stainless steel water bottle (the control). It found that between a tap water rinse (Canadian drinking water) and soap and water wash:
- No dramatic difference: The average bacteria count after 24 hours was slightly less for a tap water rinse than with soap and water cleaning.
- No dramatic difference: The average bacteria count after 72 hours was less after a soap and water cleaning than a tap water rinse.
*These numbers would likely vary significantly for water rinse versus soap and water wash for other containers like plastic or glass.
Steel hydro flasks
✅ More sanitary than plastic bottles but needs regular cleaning.
Porosity: The nonporous surfaces make these among the most sanitary water bottle containers.
Durability: Steel is resistant to corrosion and cracks, limiting the opportunity for bacteria to enter scuffs and cracks.
Cleaning: A 2018 study above finds rinsing with tap water to be not so different than soap and water washes for steel reusable water bottles.
P.S. Alcohol flasks are included
I have an alcohol flask that reads, “It must be 5 o’clock somewhere,” that I’ve enjoyed for 15 years. Like me, many folks think that because alcohol has been used as a sterilizer historically and in a pinch, flasks are inherently sterile.
False. Heat, touching your lips to the brim, and other nuances can introduce bacteria to your flask. Flasks for alcohol need to be cleansed regularly as well. You’re welcome.
Glass bottles
✅ More sanitary than plastic bottles but needs regular cleaning.
Porosity: The nonporous glass surfaces make these more sanitary than other water bottle containers (think: smooth surface without nooks and crannies for bacteria). But, unless your bottle is amber glass, the clear glass could act like a magnifying glass for light and heat, making a warm and cozy environment for bacteria.
Durability: The elephant in the room: As long as it doesn’t shatter, crack, or chip, glass can stand the test of time with durability. But that’s one major caveat, we know.
Cleaning: Soap and water will cleanse glass bottles adequately, but being dishwasher safe is the biggest timesaver to sanitize.
Hard plastic water bottle
✅ Less sanitary than steel or glass bottles so clean and sanitize multiple times weekly.
Porosity: These bottles are more porous than most reusables, which means they can absorb and hold onto odors, flavors, bacteria, and chemicals.
Durability: Durability is a meh. Hard plastic bottles can be vulnerable to cracks and scuffs, giving bacteria an alternate route.
Cleaning: Since plastic bottles are more porous, cleaning with natural agents like soap and water and opting for natural deodorizers like lemon, vinegar, and baking soda can help keep them fresh and clean. Deep cleaning now and then with a little bleach or putting it in your dishwasher a couple of times per week is also advised by the CDC.
Water pitcher (or single-serve coffee machine water tank)
✅ Clean (at least) when swapping water filters.
Porosity: These bottles are more porous than most reusables, which means they can absorb and hold onto odors, flavors, bacteria, and chemicals.
Durability:Durability is also a meh. Hard plastic containers can be vulnerable to cracks, giving bacteria an alternate route.
Cleaning: Cleaning weekly with soap and water is recommended, and monthly deep cleaning wouldn’t be a bad idea. Don’t skimp on descaling these either. Descaling — removing the mineral deposit in water appliances — is necessary to remove mineral buildup inside. That “scale” of calcium, limescale, and other minerals is a breeding ground — an Airbnb — for bacteria.
Tea kettle (including electric kettle)
✅ Clean and descale regularly.
Porosity: Stainless steel or glass tea kettles have low porosity, which limits bacteria from getting embedded in the surface.
Durability: Since it’s resistant to corrosion and cracks, it has more durability to limit the opportunity for bacteria to enter scuffs and cracks.
Cleaning: A 2018 study finds rinsing with tap water to be not so different than soap and water washes for steel reusable water bottles. Additionally, descaling is necessary for tea kettles and coffee machines to remove mineral buildup. That “scale” of limescale and other minerals is a breeding ground for bacteria.
5-gallon water jug
✅ Clean between each refill — inside and out.
Porosity: Just like other plastics, these large jugs are somewhat permeable.
Durability: More durable than small water bottles, but the weight when full makes these jugs prone to wear. Since these are refilled by lugging in and out of the home, the plastic can be prone to scuffs, cracks, and leaks over time.
Cleaning: OK, safe space, right😬? Truth be told, I was today years old when I learned I should be cleaning the family’s 5-gallon water jug each week between refills. Soap and water will do the trick, and we have tips for deep cleaning below, in addition to brushes made especially for these tall jugs!
Hydration backpack
✅ Clean the bladder, tube, and mouthpiece after each use.
Porosity: Slightly porous. And since hiking is often done in warmer weather (with the hydration backpack against your sweaty back!), it’s likelier for bacteria to thrive.
Durability: Hydration bladders are pretty durable but still prone to punctures or connections, leaving space for water to leak out and bacteria to infiltrate.
Cleaning: It’s recommended to wash your hydration bladder with soap and water after each use. If you have the bright idea to put anything other than water in the bladder (Margarita Man at the music festival, yeah we see you!😏), a deep clean immediately afterward is wise.
Pro tip: Experienced outdoorswoman Chelsea Logan recommends using a straw brush to clean the hose and, after washing the bladder, prop it up upside down and hold it open to air dry with a spatula, loosely stuffed paper towels, or kitchen tongs. I tried propping it upside down with a stainless steel champagne flute!
Thanks to Amazon and modern advances, if you can imagine any type of water container, blessedly, there is a brush perfectly sized to clean it, the straw or spout, and the lid.
We’ve got a few recommendations below, but whether you’re doing a deep clean or a daily wash, there are at least three methods: natural cleaning agents, good old-fashioned chemical sanitizers, and some tools and gadgets to get the job done.
You’ll want to cleanse screw-on grooves with one of the small brushes. Hinges of flip-top lids need attention too, as moisture can stray there. If you’ve got a straw lid, you’ll want to thread that through with a straw brush like those old-school novelty groan tube noisemakers.
The
Au naturel
For a weekly deep clean, you can concoct a baking soda scrub or a vinegar solution.
Baking soda scrub: Create your own paste using two simple ingredients.
- 1 tablespoon baking soda
- 1 tablespoon water (or equal parts depending on size and number of containers to be cleansed)
- scrub your water bottle and rinse off well
Vinegar solution: You’ll come to learn (if you haven’t already) that white vinegar is your secret solution to cleaning and sanitizing most household items and features. In this case, you stir:
- 1 part white vinegar
- 4 parts water
- fill a bottle and let it marinate for 10 to 15 minutes
- after cleaning, rinse your containers in hot water
With both methods, it’s important to let your containers air-dry fully, with no cap. Again, moisture and warmth are gateways to multiplying any remnants of bacteria or mold particles.
Rubbing alcohol or hydrogen peroxide: Both over-the-counter and medical-grade disinfectants are sound germ-killing options for outer surfaces:
- 1:1 equal parts hydrogen peroxide or rubbing alcohol to water
- wipe the outer surface down and allow to fully air dry
Descale with lemon: The acidity in lemon slices or lemon juice makes them ideal for descaling kettles and coffee makers:
- since it’s the acid we’re interested in, it’s really personal preference to use fresh lemons or prebought lemon juice
- fill your container with water and add the lemon slices or juice
- bring the lemon water to a boil, then let it sit for 20 minutes
- after the boiling, wash your container with soap and water
Cleaning agents
Bleach is a go-to sanitizing agent, and the CDC recommends using
The CDC also advises that rubbing alcohol is a sound sanitizer for the spouts and lids, and outer surfaces.
Here’s one we like for cleaning:
Gadgets
Now that you’re all informed, you may want to inspect your existing containers and look for clues.
It’s wise to check if your water bottle or container is dishwasher safe; this might be the most convenient method to totally sanitize. Here’s a quick guide:
Dishwasher safe
Dishwasher safe will have some variation of plates with water overlaying them. If you don’t see a symbol, don’t risk melting your bottle!
Top-rack dishwasher safe
Top-rack only dishwasher safe has some variation of water above the plates, not touching them.
If you see any cracks or odd smells between the outer and insulated layers of a bottle, it’s time to say “buh-bye” and replace.
Our water bottles are freaking gross. Grody, stank. Yes👏🏾you👏🏾 really👏🏾 need👏🏾 to👏🏾 clean👏🏾 that.
The good news is that a simple rinse or wash after each use with soap and water will limit bacteria growth. An intermittent deep clean with bleach, baking soda, vinegar, or the dishwasher when safe for the container should keep you safe and sanitary.