Is filtered water healthier than tap water and bottled water? Or is bottled water the healthiest option? We decided to compare the three and find a scientific answer to the question. The study is based on Europe and North America for the purpose of simplification but will also be valid in many other regions of the world.
This article is an extensive piece of research. Jump to the bottom for the conclusion.
Nutrients in water
Before looking at the individual sources of drinking water it’s important to understand what the potential nutrition contribution of drinking water is. Many people consume mineral waters because of the perception that they may be more healthful but are they?
WHO held a conference in 2005 with experts from around the world to investigate. At the conference information was shared from over 80 epidemiology studies of varying quality over the last 50 years which have addressed the issue of hard water consumption, mineral impact on health and possibly reduced incidence of ischemic cardiovascular disease in populations.
Water supplies for tap and bottled water are highly variable in their mineral contents and, while some contribute appreciable amounts of certain minerals either due to natural conditions (e.g., Ca, Mg, Se, F, Zn), intentional additions (F), or leaching from piping (Cu), most provide lesser amounts of nutritionally - essential minerals.
With all of these considerations in mind, the nutrients sometimes found in drinking water at potentially significant levels of particular interest are:
- Calcium–important in bone health and possibly cardiovascular health
- Magnesium–important in bone and cardiovascular health
- Fluoride–effective in preventing dental caries
- Sodium–an important extracellular electrolyte, lost under conditions of excess sweat
- Copper–important antioxidant function, iron utilization and cardiovascular health
- Selenium–important in general antioxidant function and in the immune system
- Potassium is important for a variety of biochemical effects but it is usually not found in natural drinking waters at significant levels.
The meeting concluded that on balance they indicated that
- the hard water beneficial hypothesis was probably valid, i.e. hard water which has more minerals reduces cardiovascular diseases
- that magnesium was the more likely positive contributor to the benefits.
Read more about the “Health benefits of mineral water”.
Source: WHO Water Saniation Health Conference 2015, http://www.who.int/water_sanitation_health/dwq/nutrientsindw.pdf
For the past 30 years the bottled water and in particular the mineral water industry has lead us to believe that their water is the healthiest option. But is there any real evidence or proof of this?
First of all the definitions of bottled mineral water differ between North Ameria and Europe.
According to the US FDA “Bottled water labeled "mineral water" must contain no less than 250 parts per million of dissolved solids, coming from a source at one or more bore holes or springs, originating from a geologically and physically protected underground water source and cannot have added minerals.”
Source: FDA, Bottled Water - Keeping it safe.
European legislation (2009/54/EC Directive) natural mineral waters are “originated from an aquifer or underground reservoir, spring from one or more natural or bore sources and have specific hygienic features and, eventually, healthy properties”
A study of bottled water in 2001 in North America concluded that bottled water generally contained the same amount of minerals as tap water. In Europe however the mineral content on average was higher.
What are the benefits of mineral water?
There are many studies specifically focused on showing the positive health benefits of certain minerals in bottled water. This includes calcium, magnesium, bicarbonate, chloride, iron, sulphate or combinations thereof.
For example: "Effects of a bicarbonate-alkaline mineral water on gastric functions and functional dyspepsia: a preclinical and clinical study by Bertoni M et al in 2002;46(6):525–531."
However, these studies confirmed that minerals are healthy and not necessarily that mineral water is healthier than other water. As per above tap water or food with these minerals will provide the same health benefits. For example:
- Chloride - salt and vegetables
- Bicarbonate - bread
- Magnesium - black beans, spinach, banana
- Calcium - dairy, broccoli, almonds, kale
- Potassium - banana, potato, broccoli, zucchini
- Sulphate - eggs, garlic, broccoli, kale
- Iron - spinach, broccoli, dried fruits, nuts
For regions where people lack a varied diet of vegetables and fruits the mineral content of drinking water could however make a difference as per the conclusion from the 2005 WHO Conference.
What are the negative aspects of bottled water?
Many studies have also focused attention on the safety of bottled mineral water, in particular on the migration of chemicals from plastic containers to water. Plasticizers (additives used to impart flexibility and handling properties to several kinds of plastics and endocrine disruptors (EDs - chemicals that interfere with function of the endocrine system) are the main compounds involved in adverse effects on human health.
One concern about bottled mineral water is related to the release of chemicals from bottles to water. Among these are the plasticizers, like the Di(2-ethylexyl)phthalate (DEHP) - widely used as plasticizer and is also present in PET bottles.
Source: Migration of phthalates from plastic products to model solutions. Coll Antropol. 2003;27(Suppl 1):23–30. PubMed>
The EDs represent another important issue for bottled water. Some in vitro studies investigated the exposure to chemicals with estrogen-like activity in bottled mineral water. Pinto et al. analyzed 30 samples of nine Italian mineral waters, stored in PET bottles, and the results show that 90% of samples elicited an estrogenic activity lower than 10% of the activity induced by the reference model. On the contrary, analysis on German mineral water, stored in PET, glass and TetraPak bottles, demonstrate a significantly elevated estrogenic activity in 12 of 20 brands (60). In an updated study, bioanalytical techniques and in vivo experiments with molluskan model are used to determine the estrogenicity of bottled water. The estrogenic activity of bottled water form PET containers is approximately twice compared to products from glass bottles (61).
Furthermore 29 glass and plastic bottles sold to consumers in Southern Spain were tested by the University of Granada. All of the water samples analyzed showed hormonal activity Endocrine-disrupting chemicals (EDCs).
- Screening of estrogen-like activity of mineral water stored in PET bottles. Pinto B, Reali D. Int J Hyg Environ Health. 2009 Mar;212(2):228–32. PubMed>
- Endocrine disruptors in bottled mineral water: total estrogenic burden and migration from plastic bottles. Wagner M, Oehlmann J. Environ Sci Pollut Res Int. 2009 May;16(3):278–86. PubMed>
- Endocrine disruptors in bottled mineral water: estrogenic activity in the E-Screen. 61. Wagner M, Oehlmann J. J Steroid Biochem Mol Biol. 2011 Oct;127(1–2):128–35. PubMed>
- Screening of hormone-like activities in bottled waters available in Southern Spain using receptor-specific bioassays. 2015. https://www.ncbi.nlm.nih.gov/pubmed/25454229
In addition to the plasticezers and EDs microplastics were found in 92% of all bottled water in the US and Europe according to testing of 250 bottles from 11 brands by OrbMedia in 2018. The bottles contained an average of 314.6 plastic particles per liter. In one bottle 10,000 plastic particles per 1 liter. For microplastic debris around 100 microns in size, about the diameter of a human hair, bottled water samples contained nearly twice as many pieces of microplastic per liter (10.4) than the tap water samples (4.45).
Bottled water drinkers could be drinking the equivalent of a credit card of microplastics every two weeks.
Source: OrbMedia, 15 March 2018, Microplastics in Bottled Water report. Research details: SYNTHETIC POLYMER CONTAMINATION IN BOTTLED WATER Sherri A. Mason, Victoria Welch, Joseph Neratko, State University of New York at Fredonia, Department of Geology & Environmental Sciences 14 March 2018.
Verdict: Generally mineral water is safe to drink, containing minerals with proven health benefits. On the other hand most bottles contain microplastics and/or estrogenic residue that could pose a health risk.
40 years ago few people questioned the quality of public tap water. We were warned to drink tap water in some places during short visits as sensitive tummies might take time to adopt to the local bacteria culture but that was it. Since then a growing interest in health, new research about water contaminants (e.g. nitrates, lead, disinfectant bi-products and microplastics have changed everything. People are right to be concerned and increased awareness for a fluid that we consume 2-3 liters of everyday is great. What is not good is that too many people have given up healthy tap water for bottled water due to these concerns.
Because despite the scares, water regulation and treatment technologies have improved greatly during this period and tap water quality is very likely better today. Examples of recent improvements include stringent regulation, filtering and monitoring of Arsenic in the US and introduction of UV filtering in e.g. New York.
EPA Arsenic Rule 22 Jan 2001. https://www.epa.gov/dwreginfo/drinking-water-arsenic-rule-history#Review
Colombia University 2011. http://blogs.ei.columbia.edu/2011/07/29/maintaining-the-superiority-of-nyc%E2%80%99s-drinking-water/
How healthy is drinking water with minerals?
Assuming a daily intake of water to be 2-3 liters, the water would provide >1% of recommended intake for only four minerals; copper, 10%; calcium, 6%; magnesium, 5%; and sodium, 3%. With the maximum concentration would supply about 20% of Ca, 23% of Mg, 10% of Zn, and 33% of Na.
Tap water can be a clinically significant source of magnesium, another mineral essential to the human body. Magnesium supports blood cell turnover and the immune system. According to the study published in 2002 in the "Journal of General Internal Medicine" drinking 2 liters of tap water provides between 16 percent and 31 percent of the recommended daily allowance of magnesium.
We also compared well known mineral water brands to tap water in Barcelona and New York and concluded that the tap water in Barcelona has higher mineral content than almost all mineral water.
According to the "Journal of General Internal Medicine," a study published by researchers at McGill University in March 2001 affirmed that drinking 2 liters of tap water in some cities can fulfill between 6 percent and 18 percent of your recommended daily allowance of calcium.
Most water providers offer frequently updated water quality reports online including minerals, contaminants and other substances. In the US visit the EPA website for Local Water Quality Information. For Europe a good starting point can be EU water directives per country. Also check out the “Can I drink the tap water in...” for more insights..
What are the risks of tap water?
Drinking water is delivered via one million miles and kilometers of pipes across Europe and North America. Many of those pipes were laid in the early to mid‐ 20th century with a lifespan of 75‐100 years. With utilities averaging a pipe replacement rate of 0.5% per year, it will take an estimated 200 years to replace the system – nearly double the useful life of the pipes. Some of these pipes still contain lead and copper but there are also issues with leakage and contamination.
EPA has created an action plan to address lead and copper issues in particular but also to improve digital reporting, training & transparency, technology to measure water quality and review unregulated contaminants and add them to future regulation.
Read more about tap water pipe corrosion quality issues and impact.
What’s the risk with lead in tap water?
In 2016, the Journal of the American Water Works Association published a National Survey of Lead Service Line Occurrence, summarizing survey data about the prevalence of lead service lines across water systems in different cities and regions of the United States. Approximately 30% of surveyed water systems reported the existence of lead service lines, and the paper’s authors estimate there are at least 6.1 million lead service lines across America’s community water systems.
In 2016, the American Academy of Pediatrics issued, Prevention of Childhood Lead Toxicity, outlining the scope of child lead exposure in the United States, its health impacts, and management guidance. The report asserts that there is no safe level of lead in blood.
Published reports have revealed increased risk of colorectal cancers in people exposed to chlorinated drinking water or chemical derivatives of chlorination.
There is inconclusive evidence from observational studies that disinfection by-products (DBPs) in drinking water are associated with colorectal cancer.
This meta-analysis of the best available epidemiological evidence indicates that long term consumption of chlorinated drinking water is associated with bladder cancer, particularly in men.
Research by OrbMedia recently found that 83% of water samples collected across five continents tested positive for the presence of microplastics (US 94% and Europe 74%). We don’t know the health risk of this yet but it’s certainly not positive.
Source: OrbMedia September 2017
Read more about the impact of consumption of microplastics.
Verdict: Public tap water is generally safe to drink. Some tap water also has the same amount of minerals as the most mineral rich bottled water. However, just like with mineral water there are risks due to well known contaminants such as lead, chlorine bi-products and new ones like microplastics and pharmaceuticals.
Filtered tap water
Home water filters are nothing new but recent advancements have made the filtering process better, the filters easier to install and use, reduced cost and vastly improved sustainability. This means that having a water filter installed at home is now feasible for any household in Europe or North America.
The choice of water filter will impact the quality of the water a lot. In some cases the filtered water might be worse than tap water due to bacteria growth on the filter or removal of all minerals. Choose a that suits your needs in terms of installation, contaminant removal, volume filtered and cost. Always make sure that it’s a credible brand and that the filters have been independently tested in accordance to international standards such as NSF.
The most common water filters today are pitchers/carafes, gravity filters on top of the sink, under-the-sink RO and Activated Carbon filters, refrigerator filters, UV-light and destilliation and faucet filters. Generally the best value for money and sufficient filtration for Europe or North America is a faucet filter with a carbon block. Read comparison of drinking water filters here.
What are the benefits of filtered tap water? Is filtered tap water healthier?
As outlined in this document both tap water and bottled water is facing major challenges with contamination and aging infrastructure. Some of these problems such as microplastics will take decades to solve. Therefore point of use filters that removes or vastly reduces such contaminants can reduce the risk of contamination and thus improve the health of individual households.
A recent study also concluded that “Activated carbon based tap water filters could provide an important short-term public health benefit through removal of halogenated DBPs, but regular filter cartridge exchange is critical to maintain a good filter efficacy”.
Source: Point-of-use water filters can effectively remove disinfection by-products and toxicity from chlorinated and chloraminated tap water, Environmental Science: Water Research & Technology, Issue 5 2016
What are the negative aspects of filtered tap water?
Some filters such as reverse osmosis remove all good and bad content of the water. This means that there are no minerals left after the filter process. With a varied diet this probably does not matter. In addition to this the water typically tastes flat and is less filling.
Another challenge is when the filters unintentionally make the tap water worse over time.
A recent study of PoU (Point of Use) reverse osmosis water filters revealed widespread bacterial contamination in the treatment devices. Other studies have come to similar conclusions. The use of reverse osmosis filters is only advisable if the devices are constantly and carefully maintained.
This also applies to activated carbon filters that trap, but do not kill bacteria. Because the filter cannot kill bacteria, it may actually becomes a breeding ground for the microorganisms if not changed regularly. An old, unchanged PoU filter can be dangerous because its use may add bacteria, which had been killed in the tap by chlorine, back into water. As long as the filters are changed as per instructions this risk is minimal.
Similar tests by a laboratory in Germany concluded that 24 out 34 filters tested increased the amount of bacteria.4 out of 6 had higher bacteria count after 7 weeks than the tap water.
Verdict: A fit for purpose quality water filter will vastly reduce the risk of contaminants in tap water and may therefore have long term health benefits. The wrong water filter or a poorly maintained one could however increase risk.
Conclusion - filtered vs bottled water vs tap water?
All three types of water including bottled mineral water, tap water and filtered water are generally safe to drink in Europe and North America. Therefore the choice is really about eliminating risk and thus improving long term health prospects. Fully eliminating risk is impossible, and because gauging risk is so difficult, safety is really a matter of managing risk to a reasonable degree, not trying to eliminate them altogether. Safe and risk-free are different things.
Here’s our attempt to rate filtered vs bottled water vs tap water
|Bottled Mineral Water
Low to High
Depends on bottle
Low to High
Depends on location
Zero to High
Depends on the type of filter
|Very low risk
Conclusion: A quality water filter independently tested for the type of tap water in your household will reduce risk and thus likely have long term health benefits.
A 2012 Committee Opinion on Lead Screening During Pregnancy and Lactation by the American College of Obstetricians and Gynecologists outlines the available evidence related to lead exposure and maternal-fetal health. While the opinion does not recommend routine blood-lead testing for all pregnant women, it recommends steps for pregnant and lactating women whose blood levels exceed certain thresholds.
This review showed that various meta-analyses and pooled analyses have found statistically significant excess risk for some indicator of exposure to chlorinated water or trihalomethanes and bladder and colorectal cancer, small for gestational age, still birth, all congenital anomalies combined and ventricular septal defects, but no statistical significant excess risk for many other congenital anomalies. The excess risk was generally small, but robust, with little sensitivity to the results of individual studies or evidence of publication bias.
Pharmaceuticals in tap water:
Are pharmaceuticals in tap water an issue?
Are water filters BS?
An analysis of the need for water filters when public water is safe and clean for drinking.