Filtered and bottled water are both popular alternatives to tap water, but because they’re both considered to be expensive, people want to know that they’re making the healthiest, cheapest, tastiest, and most environmentally friendly choice.
Bottled water is less healthy, more expensive, more environmentally wasteful, and no tastier than filtered water, according to an abundance of scientific research.
In 2020-2021, researchers at Consumer Reports cooperated with The Guardian US to test the tap water from water systems that together served more than 19 million Americans. They discovered a whole range of dangerous chemicals in the water, with 118 of the 120 samples containing man-made chemicals (PFAS), arsenic, and lead, the first two above recommended safe levels.
This is why it does not help to tell Americans that their tap water is the safest in the world. People want a safe alternative to tap water, whether it is bottled or filtered water.
This is why it is important to find out which water is best, filtered or bottled.
The aim of this article is to summarize the research and tell you whether it is better to drink filtered water or bottled water.
The Presence of Potential Health Hazards in Water
Various types of filters work in different ways and remove different contaminants, as certified by the health organization NSF International. So, let’s first look at the contaminants removed by water filters.
Pitcher filters like Brita and PUR almost always have the same structure. A basic mesh screen to capture big particles, an activated carbon filter that removes particles like chlorine and minerals that does 60 percent of the filtering job, and a basic ion Exchange Resin filter that targets specific dangerous substances like copper and cadmium.
They remove most contaminants with a health effect (NSF/ANSI 53) and aesthetic impurities like chlorine and taste/odor (NSF/ANSI 42), but some TDS (total dissolved solids), including a tiny bit of metals and minerals, remain in the water.
Faucet-mounted filters are plain activated carbon filters that leave some TDS in the water after removing dangerous amounts of them. They normally remove fewer particles than pitchers that incorporate some ion exchange technology.
Reverse Osmosis Systems
Most reverse osmosis systems tend to be under-sink systems with multiple filters that can remove almost all foreign particles, especially the potentially harmful chemicals and metals regulated by the EPA (Environmental Protection Agency). They tend to be more thorough than pitchers and faucet-mounted devices because they include multiple types of filters.
Reverse osmosis membranes alone without any other filters can remove metals and minerals, since their molecules are physically larger than those of water, but not chlorine or volatile organic compounds (industrial chemicals) that are dissolved in water. That’s why reverse osmosis membranes alone aren’t popular.
Distillers boil water and then collect the water vapor as it condenses. Since minerals/metals and bacteria cannot convert to gas, this process removes them from the water. Volatile organic compounds, however, including the industrial chemicals that commonly contaminate soil and water, can convert to gas and thus cannot be removed by a distiller.
Ultraviolet light and devices with an antimicrobial substance like silver are the only ones that are certified to remove viruses and bacteria from water. They are the only filters that are allowed to carry an NSF/ANSI standard P231 certification.
Viruses and Bacteria Removing Filters
The Epic Nano Pitcher and the LifeStraw Home Pitcher are two of the few devices on the market that can do this, as well as remove heavy metals and chemicals like chlorine. This can be important if you use well water, but municipal authorities already remove these organisms from tap water and are required to test for it every 90 minutes.
Therefore, the ion Exchange Resin and combination reverse osmosis systems are the most thorough, but pitchers and faucet-mounted systems like Brita and PUR are definitely certified to remove heavy metals and chemicals with harmful health effects.
Bottled Water VS. Filtered Water
So, how does bottled water match up to these systems regarding the presence of contaminants?
In general, all bottled water contains TDS, which means they aren’t as clean as the water produced by ion Exchange Resin and reverse osmosis systems. For example, one study found TDS scores between 11 and 317 PPM in 14 brands, and another found some brands to have TDS higher than 500 PPM, which is higher than the EPA recommends for drinking water.
But this is harmful only if the TDS in the water are unhealthy, so let’s see what the research says.
One potential health hazard is the lack of expiration dates on labels. In one survey of 40 brands, scientists found expiration dates on only 13 of them. Since organisms like bacteria can live in water, and since compounds leach from the packaging materials with longer storage, it is definitely safer to have an expiry date.
Lead & Cadmium
In the same survey, the researchers found that three brands exceeded the recommended amount of lead and cadmium for drinking water. Lead can cause reduced cognitive performance and attention deficit disorder, while cadmium can cause cancer. Other studies found safe levels of lead, cadmium, arsenic, and aluminum in all the samples they tested. All the above water filters remove these.
At least two studies in Australia and the United States have found naturally-occurring radioactive elements in bottled mineral water at levels higher than are recommended by water authorities. One concluded that the lifetime radiation dose from bottled water was lower than that judged to be dangerous by the International Commission on Radiological Protection, but most of us might balk at consuming so much radioactivity throughout our lives.
We don’t know how well faucet-mounted and pitcher filters remove these, but the EPA does recommend reverse osmosis to do this and some studies have found activated carbon filters to be effective.
Endocrine Disrupting Compounds
Some studies have stumbled across endocrine disrupting compounds, which are substances that interfere with our hormonal systems, in 78, 60, and 10 percent of the mineral water samples they tested. These included everything from estrogens, progestogens, androgens, and glucocorticoids, some arising from the ground contamination of mineral springs, and some from the deterioration of the PET plastic bottles in which water is stored, especially with prolonged storage and exposure to sunlight and high temperatures.
While the researchers suspected that the level of exposure was still safe, they admitted that no research was available on daily, life-long exposure to these hormones and warned about possible interference with human reproductive systems, infertility, testicular and breast cancer, reproductive tract abnormalities, thyroid dysfunction, obesity, and so on.
Industrial chemicals have also turned up in bottled water, especially those used in gasoline, paints, paint removers, dyes, nail polish, solvents, varnishes, and cleaning products. Whether they occur in large enough amounts to have health effects over a lifetime of consumption remains a mystery, but that is again a result of the pollution of springs, the leaching from plastic bottles, and possibly contamination at bottling plants.
All the above filters should remove these if they are in your tap water.
Microplastics have been found in 93 percent of all bottled water samples, and no type of water filter can remove all of them. For more information on filters that can remove high levels of microplastics from water, check out this article we wrote.
Antimony is a chemical used in 90 percent of factories that produce synthetic packaging materials, such as the PET plastic in which water is bottled. Consequently, it does appear in bottled water, again at lower levels than health authorities consider to be harmful. But because it is a powerful cause of cancer, the idea of daily lifelong exposure is not comforting. Domestic filters should remove this too.
Glass VS. Plastic Bottles
Glass bottles are no safer, with one study comparing water stored in them with that in plastic bottles and finding 19 times more cerium, 14 times more lead, seven times more aluminum and zirconium, five times more Titanium, thorium, and lanthanum, and twice as much praseodymium, iron, zinc, neodymium, tin, chromium, and terbium.
Dark and colored bottles were the worst, but still more or less below current safety recommendations. Reverse osmosis and ion exchange systems are great at removing these heavy metals.
Most Contaminated Bottled Water Brands
- One of the most damning studies was by the Environmental Working Group that unearthed an average of eight contaminants in each brand they tested. The cheapest purified tap water obtained from the largest supermarkets, specifically Walmart’s Sam’s Choice and Giant Supermarket’s Acadia brands, contained cancer-associated disinfection byproducts that exceeded even current safety standards.
All this does not mean that bottled water is necessarily harmful; occasional consumption is certainly safe.
But it does mean that your filtered tap water is safer, especially if you filter water through multiple filters like the Epic Nano Filter Pitcher (Epic Water link), ZeroWater pitcher (Amazon link), or under-sink reverse osmosis systems like the top-rated iSpring RCC7 under-sink filter (Amazon link) that can remove most of these potential hazards.
The Presence of Minerals and Electrolytes
Most minerals and electrolytes are healthy and required for good health. Electrolytes are particles that carry a positive or negative electric charge once they’re dissolved in a liquid. These include calcium, potassium, magnesium, sodium, and so on.
Bottled mineral spring water brands pride themselves on their inclusion of these healthy minerals/electrolytes, so let’s see how they compare with domestic water filters.
- Reverse osmosis systems, distillers, and ion Exchange Resin systems like ZeroWater’s pitchers are specialists at removing metals and minerals. This results in zero or almost zero minerals in your water.
In Israel, where desalinated sea water produced through reverse osmosis systems have become commonplace, researchers have discovered that ischemic heart disease have increased because of this decline in magnesium intake. A Taiwanese study has concluded that people with low water-related magnesium and calcium intake were more likely to suffer from gastric cancer.
- Basic pitchers and faucet-mounted filters that use primarily activated carbon filters, like Brita and PUR, remove only a limited amount of minerals, but leave the rest untouched. This makes them healthier than the more thorough filters are, except for the fact that the less healthy minerals like iron, copper, and sodium, also escape their filters. More about this below.
- Canadian researchers have discovered a large variation in the mineral contents of different bottled mineral water brands, with healthy levels of calcium, magnesium, and potassium. The sodium concentration was, however, twice as high across almost all brands, at levels that can be higher than the recommended daily sodium intake for adults. This means that many brands, and almost all mineral water brands, pose a nasty blood pressure risk if consumed daily.
This suggests that, even though it is true that we can obtain up to half of our required daily magnesium, calcium, and potassium intake from bottled water alone, it might be healthier to obtain them by eating fruit and vegetables and to use filtered water for hydration.
The Taste of Filtered VS. Bottled Water
The one that tastes better has an advantage over the other, or that’s what logic suggests. But research actually shows that people are surprisingly bad at tasting the differences between different types of water.
In a study published in the Journal of Wine Economics in 2018, researchers gave more than 100 study participants a variety of tasting tests with four types of bottled water and tap water.
Firstly, they had to distinguish between four types of bottled water, which they managed only slightly better than random chance.
Secondly, they had to distinguish between bottled and tap water, which they couldn’t do at all.
Thirdly, they had to match the taste of the different water types with expert descriptions of their tastes, which they could not do either.
From these findings, the scientists concluded that people did not express strong preferences for one type of water over another, since they couldn’t even tell the difference.
A 2010 study in the Journal of Sensory Studies also found that people could not tell the difference between six types of bottled water and six types of tap water once chlorine had been removed from the tap water. Those who could distinguish between them preferred slightly mineralized water with a TDS score between 300-530 PPM, which is a little lower than the amount in unfiltered tap water and a little higher than that in filtered water.
From these studies, we can conclude that you probably won’t be able to taste the difference between filtered and bottled water. If you can, you are more likely to prefer bottled water to which a few minerals have been added, or activated carbon filters like Brita and PUR that leave in some TDS.
ZeroWater and other devices that make use of five or more filters, such as the iSpring RCC7 under-sink filter, tend to remove all minerals, so their water may taste flat.
At the other extreme, bottled mineral water and water filtered through domestic alkaline filters, such as the popular Apex MR-1050 Countertop alkaline filter (Amazon link), have substantially more minerals than 350 PPM of TDS, which places them outside the best taste category too.
Affordability of Filtered VS. Bottled Water
An examination of Amazon’s bottled water sales shows that the average price for consumer-sized amounts is approximately three dollars per 33.81 ounces (one liter). 12 large 33.81 bottles are cheaper than 24 16.9-ounce bottles ($30 VS. $40). These include common brands like Fiji, Nestle Pure Life, Evian, Essentia Alkaline Water, and Acqua Panna.
At closer to two dollars per 33.81 ounces, Aquafina and Dasani are cheaper, as they are no more than filtered tap water.
ZeroWater, Brita, and PUR all sell their 10-cup pitchers and faucet-mounted filters for an average of roundabout $33, with under-sink five-stage reverse osmosis systems costing around $200. On average, you can expect to pay $30 for replacement filters per year for the former and $50 for the latter.
Brita and PUR rate their filters for two months or 40 gallons of use and ZeroWater for 20 gallons.
Distillers, which are not as popular for home use, require electricity to heat the water to create steam, and reverse osmosis systems waste three gallons of water per one gallon of filtered water produced, at $0.004 per gallon.
From these facts, we can conclude the following:
- Bottled water costs $320 per gallon.
- A filter pitcher or faucet-mounted filter costs $33 plus five to six dollars per gallon. A few years ago, the Environmental Working Group calculated water produced by these filters to be 12 times cheaper than bottled water.
- A reverse osmosis system costs $200 plus less than one cent per gallon.
- Those who drink 33.81 ounces (one liter) of water per day spend $912.5 on bottled water per year, those who filter it through pitchers or faucet-mounts spend $30 per year, and those who use reverse osmosis spend $50 per year, assuming that they’ve paid for the original devices. This is consistent with a 2016 study that showed that reverse osmosis was between eight and 19 times cheaper than bottled water.
Therefore, filtered water is substantially cheaper, even if you buy the most expensive multi-filter device.
The Environmental Impact of Bottled and Filtered Water
Both filtered and bottled water carry environmental costs, but bottled water is far worse.
- Plenty of research has been performed on the amount of plastic that is dumped because of bottled water, all of them producing different numbers, but the average is millions of tons per year in the United States alone. These bottles are recyclable, but this does involve electricity and industrial chemicals, a definite environmental cost.
Water filters are also recyclable, and since they produce everything from 20 to 40 to hundreds of gallons of water per filter, their use and recycling are environmentally much more economical.
- More energy is required to produce and use bottled water than filtered water. The production of the bottles and the transport to supermarkets or warehouses are responsible for most of the energy costs, and because each bottle contains substantially less water than each filter can clean, these production and transport costs are lower for filters. Glass bottles are especially energy-hungry to produce.
- One study that ranked water sources on their environmental costs of the raw materials and energy inputs found tap water to be the most environmentally friendly, followed by domestic reverse osmosis systems, followed by plastic and then glass bottled water, which were by far the worst.
This shows that bottled water is environmentally incredibly destructive, an issue that you can rectify by using filters and, importantly, by recycling them according to the instructions on the manufacturer’s website.
Compared with filtered water, bottled water is less healthy, more expensive, and more environmentally destructive. It also does not taste better. There is, accordingly, no good reason to consume it regularly.