So just how disgusting are our water bottles?
“You’re telling me I have to wash my water bottle every day?!”.
“But I live in ______, and we have the best water quality…”
“Can’t I just use soap and water?”
These are some of the questions that people ask us when they discover Nuvoe, our latest product that’s just launching on Kickstarter. All these questions are very valid! I thought it would be interesting to share the science we’ve amalgamated that ultimately led us to create this product.
Bacteria and viruses live in a microbial world that’s omnipresent but invisible to us. We interact with it all the time by being carriers or providing it with nutrients allow it to thrive, and the only time it makes itself known is when we get infected or sick, or when we simply come across an unpleasant smell. It’s no surprise then that when we gleam into this microbial world we can be quite surprised by what we see.
Given that access to clean drinking water is such an important part of our lives the scientific literature surrounding water quality is quite extensive. Unfortunately, it’s not as ideal as we like it to be.
Bear with me, this is going to get quite scientific! For those what want a quick summary, here’s the TL;DR for your convenience:
Even the in the world’s most regulated countries, municipal tap water isn’t bacteria-free, and even when it’s been chlorinated and treated, the levels of bacteria present grow into alarming levels even at room temperature. Using a filter could make it worse, and water bottles are great at harbouring germs at alarming levels thanks to the added nutrients and bacteria from our backwash. Single use plastic bottles are a solution but it’s terrible for the environment and it’s costly. It seems like a war we can’t win. That’s why we created Nuvoe.
Bacterial concentrations in tap water.
Back in 2018, the Scientific American wrote an extensive piece titled “A Wave of Resurgent Epidemics Has Hit the U.S.”  (which on a side note, is a quite interesting article given our current pandemic-ridden context in 2020). One of the most striking pieces of data from this piece is that over 19 million Americans are sickened by microbe-contaminated water every year, a number further corroborated by the New York Times.  That’s quite a hefty number.
More often than not, municipal water is treated before being distributed, so where do these microbes come from? According to Kelly Reynolds, an environmental and occupational health scientist at the University of Arizona School of Public Health, it’s from the pipes in the water distribution networks which have become old and leaky and “where water can leak out, contaminants can leak in”. Some estimates indicate 10–20% of water leaks out over the course of its journey from local reservoirs.1
Bacteria can be found even in the world’s most rigorously treated water sources. Regulation in countries like the Netherlands, Sweden, Germany, Japan, Australia and New Zealand dictates that drinking water must have a heterotrophic bacteria concentration (HPC) of less than 100 CFU/mL . HPC is commonly used to assess the bacterial quality of water and is an indicator of the overall bacterial quality of the water. Other countries like Taiwan are lenient up to levels of 200 CFU/mL. The EPA in the USA and the CCME in Canada are less rigorous and set their permissible levels at 500 CFU/mL. [3,4]
Doesn’t chlorination help reduce the concentration of bacteria? In part, yes, chlorination is a big component in the treatment of municipal water and helps reduce the HPC count to the previously listed levels. Studies have shown however that significant bacterial growth can occur in treated, chlorinated water left at room temperature for as little as 8–24 hours. 
That’s okay, I use a filter.
The vast majority of us refill our water bottles from this municipal tap water. Some choose to first filtrate the water with something akin to a Brita filtration pitcher/jug. Studies that have looked at how these filters change the microbial quality of the drinking water show results opposite to the desired direction. Over 70% of the filters in the experiment had bacterial counts increase up to 6,000 CFU/mL, far higher than the 100–500 CFU/mL recommended for drinking water. 
The paper also states:
We found that most commercial filters tested produced water with higher bacterial counts than in water prior to filtration, suggesting biofilm formation and bacterial growth in the filters especially after one week of use. Most species isolated from filtered water can cause life-threatening infections in severely immunocompromised patients, especially after colonizing the gastrointestinal tract.
What is biofilm? It’s microorganisms like bacteria that stick to each other and build up along surfaces. Warm, moist breeding grounds create an ideal environment for biofilm formation. Sometimes it can be spotted as a slimy substance that coats places that are hard to clean. A common example is plaque that forms on the surfaces of teeth. And it grows inside the very water we think has been clean.
In some of the tested pitchers, bacterial colony counts of the filtered water were over 10,000 times that of the tap water which was first placed in the pitcher. The paper doesn’t delve into why this occurs but it could be that filtration removes the chlorination, allowing for quicker bacterial growth. The paper flags that filters themselves could be a source of contamination and a contributing factor as 5 of 13 tested filters were contaminated with bacteria and moulds.
Water bottles, the perfect incubator?
So what happens when we refill our water bottles with this water then? It’s not good news. One particular study assessing the bacterial quality of the water has shown that over 60% of water bottles had a HPC result higher than 500 CFU/mL, and over 70% had a HPC result higher than 100 CFU/mL. 
The same study also assessed the coliform concentration of the same bottles and 23% of them contained more coliform concentration than the standard of microbiological quality established by the FDA which is 1 CFU/100mL. Some bottles contained coliform counts greater than 150 CFU/100mL!
Coliforms are a particularly hazardous bacteria that grow in water. Examples include Escherichia coli (E. coli) and Staphylococcus aureus (more commonly known as golden staph). Strains of E. coli can cause infection and induce symptoms like diarrhea, stomach cramps, vomiting, fever, and in extreme cases, pneumonia and UTIs. Staph bacteria has a similar range of symptoms when digested and is one of the most common causes of food poising.
A similar study assessed the bacterial quality in the personal water bottles of elementary school children and yielded very similar results. Over 65% of bottles in this study have levels of bacteria that exceed 500 CLU/mL with only just over 15% having less than 1 CFU/mL.  Likewise ~15% of bottles had coliform bacteria that exceeded the FDA standard of 1 CFU/100mL with over 9% of bottles having greater than 1,000 CFU/100mL!
A separate experiment on the bottles of gym-goers found 90% of the bottles had bacterial contamination. [9,10] 26% tested positive for S. aureus and 16% for E. coli, the two most frequent species detected.
So where does this bacteria come from?
Some of it is in our water bottles. According to experts in water quality, we need to wash our water bottles every single day thoroughly, not just rinse, but wash with soap, hot water and a bottle brush to eliminate biofilm build-up and get at all the nooks and crannies where bacteria could be happily residing. [11,12,13] According to the FDA Food Code , water is considered a food. Reusable bottles are therefore food-contact surfaces and require proper cleaning and sanitising. 
And some of it is from bacteria that’s already present from our water supplies, whether that’s straight from tap municipal water or filtered water which often harbours more germs. We also know that bacteria can grow even in treated & chlorinated water at room temperature as previously explained. Now add to that bacteria and nutrients that’s newly introduced from our backwash. Whether we like it or not, and no matter how careful we are, backwash always occurs. Backwash not only provides the bacteria for transmission but also nutrients that allow the microorganisms to fruitfully multiply. We are the ones adding fuel to the fire that’s happening in our bottles. 
Water bottles also check all the boxes for bacterial growth: moisture, nutrients, darkness, room temperature, low salinity, neutral pH, and time. It’s hard to argue why water bottles aren’t the perfect incubator for germs.
I’ll just drink bottled water.
It’s not surprising then that people would prefer to buy and drink from single-use plastic bottles. However, that’s not a sustainable solution. Waste from single-use plastic bottles are a huge problem. Globally humans buy a million plastic bottles per minute. Unfortunately 91% of all that plastic is not recycled. Most of these bottles end up in landfills or in the oceans, and PET (the plastic most commonly used for single use bottles) takes over 400 years to decompose. 
So municipal water isn’t bacteria-free, and even when it’s been chlorinated and treated the levels of bacteria present grow into alarming levels even at room temperature. Using a filter could make it worse, and bottles are just great at harbouring germs at alarming levels anyway thanks to the added nutrients and bacteria from backwash. Single use plastic bottles are a solution but it’s terrible for the environment and it’s costly. It seems like a war we can’t win.
Nuvoe uses UV-C light to sanitise both your water and your water bottle. UV-C light penetrates the cell wall, tears apart DNA and destroys the nucleic acids of microorganisms. By upgrading your bottle with Nuvoe every time you refill just give your bottle a shake to activate a cycle, and all the above goes away. It’s as simple as that!
- Moyer MW. A Wave of Resurgent Epidemics Has Hit the U.S. Scientific American. https://www.scientificamerican.com/article/a-wave-of-resurgent-epidemics-has-hit-the-u-s/. Published May 1, 2018.
- Duhigg C. Millions in U.S. Drink Dirty Water, Records Show (Published 2009). The New York Times. https://www.nytimes.com/2009/12/08/business/energy-environment/08water.html. Published December 7, 2009.
- Robertson W, Brooks T. The Role of HPC in Managing the Treatment and Distribution of Drinking-Water.; 2003. https://www.who.int/water_sanitation_health/water-quality/guidelines/HPC12.pdf?ua=1.
- US EPA. National Primary Drinking Water Regulations. US EPA. https://www.epa.gov/ground-water-and-drinking-water/national-primary-drinking-water-regulations. Published March 22, 2018.
- Geldreich EE, Nash HD, Reasoner DJ, Taylor RH. The Necessity of Controlling Bacterial Populations in Potable Waters: Community Water Supply. Journal (American Water Works Association). 1972;64(9):596–602. https://www.jstor.org/stable/41266810.
- Daschner FD, Rüden H, Simon R, Clotten J. Microbiological contamination of drinking water in a commercial household water filter system. European Journal of Clinical Microbiology & Infectious Diseases. 1996;15(3):233–237. doi:10.1007/bf01591360
- Sun X, Kim J, Behnke C, et al. The Cleanliness of Reusable Water Bottles: How Contamination Levels are Affected by Bottle Usage and Cleaning Behaviors of Bottle Owners. Food Protection Trends. 2017;37(6):392–402.
- Oliphant JA, Ryan MC, Chu A. Bacterial Water Quality in the Personal Water Bottles of Elementary Students. Canadian Journal of Public Health. 2002;93(5):366–367. doi:10.1007/bf03404571
- Matheus Baffi Silveira, Estevao Scudese, Gilmar Weber Senna, et al. Microbial Contamination in Shaker Bottles among Members of Fitness Centers. Journal of Exercise Physiology Online. 2018;21(4):134–143.
- Smith J. Just How Filthy Is Your Reusable Water Bottle? Runner’s World. https://www.runnersworld.com/news/a25671476/water-bottle-bacteria/. Published January 2, 2019.
- Bryan C. How disgusting is your water bottle, really? Mashable. https://mashable.com/article/how-often-should-i-clean-my-water-bottle/. Published October 10, 2019.
- Walden L. Water bottles contain hundreds of thousands of bacteria if not properly cleaned. Country Living. https://www.countryliving.com/uk/homes-interiors/interiors/a29423391/cleaning-reusable-bottle/. Published October 12, 2019.
- Asbrink H. Wait, You Need to Clean Your Water Bottle How Often? Food52. https://food52.com/blog/23711-how-often-should-you-wash-reusable-water-bottle. Published January 28, 2019.
- Center for Food Safety and Applied Nutrition. Food Code 2013. U.S. Food and Drug Administration. https://www.fda.gov/food/fda-food-code/food-code-2013. Published 2019.
- Nace T. We’re Now At A Million Plastic Bottles Per Minute — 91% Of Which Are Not Recycled. Forbes. https://www.forbes.com/sites/trevornace/2017/07/26/million-plastic-bottles-minute-91-not-recycled/. Published July 26, 2017