Is Bottled Water Better for Your Teeth?         

Why Bottled Water?

Bottled water has become increasingly popular over the past few decades; especially in countries with clean, safe water.  Sales have kept growing despite growing environmental concerns over the disposable bottles and the energy used in packaging and transportation.

Regardless, bottled water has become a lifestyle choice for many people and it’s here to stay.  According to the International Bottled Water Association, sales in the US reached a $19.4 billion in 2019 continuing the steady rise seen for decades [1].  

Where is bottled water from?  Sources are typically natural springs, but some of the biggest names supply filtered public water.  Each of the products has small variations in mineral content, and pH [2]. 

How does pH affect teeth?  Eating foods containing simple carbohydrates or sugars causes some oral bacteria to produce acids, lowering the pH.  As the pH in your mouth changes, the strength of the enamel is affected; if the pH is consistently low the enamel will soften until it crumbles, creating a cavity.  This concept is shown in the Stephans curve (below).

Left: Note how mealtimes initiate a drop in pH.  Now consider how snacking will keep the pH low – potentially all day [3].  

To help neutralize the acidity of meals, choose beverages that are at a pH of 5.5 or higher.  

Is an alkaline water (or diet) healthier?  The pH of the blood is tightly regulated by your lungs, kidneys and blood buffers to keep your pH within a healthy range of pH 7.35-7.45.  Deviating above that range may cause symptoms of alkalosis including irritability, muscle twitching, muscle cramps; this condition requires a physician to diagnose and treat.  No reputable published data supports ‘alkaline diets’ [4].  Don’t try to fight your body’s pH – it is a highly regulated system and doesn’t require or benefit from attempts to alter it.  As for your mouth, a water that is neutral or slightly alkaline would help neutralize the acids produced by bacteria on the teeth and would therefore help to reduce the time your oral pH is below the critical pH 5.5.  

How acidic is my bottled water?  To test the pH of common bottled waters we used a calibrated glass electrode pH meter to test 8 different brands of still bottled water.  We also tested tap water and filtered tap water.  Each sample was tested at room temperature and the test was repeated three times in series.  The pH meter was rinsed between samples and recalibrated after each series.  Mean averages of data shown.  No statistical analysis were performed.  Here are our results: 

Brand	pH
Aquafina	5.9
Alkaline 8.8 water	8.8
Dasani	5.4
Evian	7.2
Fiji	7.1
Tap	7.2
Filtered tap	7.2
Nestle Pure Life	7.2
Hinckley Springs	6.8
Ice Mountain	7.8

If you’re worried about the acidity of bottled water just stick with tap water. Well water – or from your city – is often closer to neutral than bottled water.  The standards for purifying tap water are stringent and well regulated compared to those that govern bottled water [5]. So, your bottled water may or may not be as pure as your own tap water.  

What about fluoride?  Fluoride works by increasing the acid resistance of your teeth.  It works by being substituted with the less acid-resistant calcium ion in the major component of tooth enamel, hydroxyapatite.  This simple substitution reduces decay rates and is the reason why fluoride concentrations in most municipal supplies have fluoride concentrations adjusted for optimal benefit.  Many bottled waters have minimal fluoride content.  Water that is low in fluoride and mildly acidic will push your enamel to become weaker.  

If bottled water is your choice, choose brands that are best for your teeth: If we don’t have the results you need, type  “brand X pH” and Google will give you the pH.  Our results correlated well with online data.  Find a bottled water that is pleasing to your taste and has a near neutral pH.  And remember, that the small amount of fluoride in tap water – and especially toothpaste – is beneficial to teeth of all ages [6,7].

Sincerely,

Dr. Doodes

References:

1. http://www.bottledwater.org/public/BWR_Jul-Aug_2016_BMC%202015%20bottled%20water%20stat%20article.pdf#overlay-context=economics/industry-statisticsnjnjughruruiwid9edib9gi90586989tj
2. http://www.ada.org/en/member-center/oral-health-topics/bottled-water
3. Advances in Remineralization for Early Carious Lesions: A Comprehensive Review. S Jefferies et al., April 2014, Compendium of Continuing Education in Dentistry
4. Systematic review of the association between dietary acid load, alkaline water and cancer.  Fenton TR, et al., BMJ Open. 2016 Jun 13;6(6
5. https://www.epa.gov/sites/production/files/2015-04/documents/epa816f04030.pdf
6. Critique of the review of ‘Water fluoridation for the prevention of dental caries’ published by the Cochrane Collaboration in 2015. Rugg-Gunn AJ et al.,  Br Dent J. 2016 Apr;220(7):335-40. 
7. Water fluoridation for the prevention of dental caries.  Iheozor-Ejiofor Z et al., Cochrane Database Syst Rev. 2015 Jun 18;(6)