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Methodology

Is Your Bottled Water Worth It?: Methodology

June 10, 2009

Interested in finding out how much information bottled water companies make available to their consumers, in February 2008 EWG invited the public to send labels from bottled waters that they had purchased. Between February and August 2008 we received 163 unique product labels representing 137 brands from 30 states.

EWG's researchers logged into a database the details of information on the label regarding water source, treatment and testing. We recorded similar data from company websites.

In January 2009, California’s SB 220 went into effect, requiring all bottled waters sold in that state to include on their label the source of the water and contact information for consumers to obtain a report on water quality. Aware that this new rule would prompt changes in the bottled water industry, in May 2009 EWG again invited the public to send us labels of bottled water purchased after the law went into effect. In May and June 2009 we received 85 unique product labels representing 76 brands from 32 states.

We logged the details from this set of labels and corresponding websites into the EWG database and dated the entries appropriately. The final database, a combination of information from products purchased before and after SB220’s effective date, consisted of 188 products from 155 brands and 38 states.

EWG researchers analyzed the information in the database and scored each product based on: 1) the transparency of bottled water company with regards to disclosing source, purification and testing information on both their product label as well as on their website, and 2) the efficacy of purification methods used to treat the water.

The table below details the matrix used to determine the transparency score.

Scoring system — EWG method to rate bottled water

Label DetailsWebsite Details
Water Source
Precise source name and location2 pts1 pt
Multiple, specific source names and locations listed as possibilities1.5 pts0.75 pt
Partial or vague11 pt0.5 pts
Product name is the only indicator of source0.5 pts0.2 pts
None listed0 pts0 pts
No website ---0 pts
Purification
Treatments named/Lack of treatment disclosed2 pts1 pt
Partial or vague21 pt0.5 pts
Product name is the only indicator of purification0.5 pts0.2 pts
None listed0 pts0 pts
No website ---0 pts
Testing Conducted
Statement on label with information about obtaining a water quality report1 pt---
Water Quality Report available---0.5 pts
Report lists full SDWA* contaminant list ---0.5 pts
Report lists partial SDWA* contaminant list---0.2 pts
Report includes complete documentation of all chemicals tested for---0.5 pts
Report only includes partial documentation of all chemicals tested for ---0.2 pts
Report represents the most current water quality data ---0.5 pts
Report is either a "typical" analysis or is undated ---0.2 pts
1Partial or vague source information refers to products that do not disclose specific source names and locations. Examples include phrases such as "deep within Michigan's countryside" and "a deep pristine crystalline rock aquifer".


2Partial or vague purification information refers to products that do not make clear the treatment processes used, or the lack thereof. An example is the phrase "state of the art ultra-purification system" with no further clarification.

*SDWA- Safe Drinking Water Act: "The Safe Drinking Water Act (SDWA) is the main federal law that ensures the quality of Americans' drinking water. Under SDWA, EPA sets standards for drinking water quality" (EPA, 2009).

We assigned a transparency score to each bottled water product by summing the categorical scores and then factored in purification efficacy by subtracting points where advanced treatment processes, such as reverse osmosis and distillation, were not applied.

Purification Efficacy


Advanced Treatment Used0 pts
Basic Treatment Used-0.5 pts
No Treatment Used/None Listed-1 pt

We represented the overall score as a letter grade based on the key below, and added a check mark to indicate products purified with advanced processes.

Letter grade key


A8.6 - 10.0
B6.9 - 8.5
C5.0 - 6.8
D2.9 - 4.9
F1.0 - 2.8