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How our Scoring Works

Formula behind the Oasis scoring system

How Oasis scores water

Table of Contents


We all need water, but not all water is the same. Whether it's bottled, straight from the tap, or filtered, understanding the cleanliness and health of water is vital for taking care of our health and supporting longevity. Every water has it's own unique characteristics and we've created a scoring system to help you understand the quality of the water you drink.

Please note our scoring system is subject to change in light of new scientific evidence and research. We choose to open-source our scoring system to allow for transparency and to encourage feedback and improvement.

How we score bottled water

Everything is scored out of 100 and we penalize each item depending on a few factors.

Factors we consider:

  • Source
  • Contaminant amount and levels
  • PFAS
  • Packaging/material
  • Filtration method
  • PH


The source of water is the first thing we consider when scoring water. Not all water is the same and it starts with the source. A large portion of bottled water comes straight from municipal water supplies and undergoes intense treatement to remove the countless toxins inside. This treatment strips water of it's natural minerals making it harder for the body to digest and often adds disenfenctant by-products to the water.

Other source of water include natural springs, aquifers, icebergs, deep wells, and other natural sources. Ideally the water doesn't need to be filtered much and comes from a natural source which includes healthy minerals.


  • Municipal water supply: 30
  • Mountain spring: +10 (bonus)
  • Unknown (not stated in report): 5
  • Well: 0

Contaminant amount and levels

It's hard to find water on Earth anymore without some level of contamination, however we set a high standard and believe water can only be 100/100 if it has no harmful contmainants.

We penalize water for the number of unique contaminants and the levels of each substance (based on the legal limit or health guideline).


  • Unique contaminants: 5 per contaminant (max 40)
  • Amount over guideline: level above * 2.5 (max 40)

If there is no lab report we dock the item 50 points to account for the unknown contaminants.

PFAS Levels

PFAS satnd for per- and polyfluoroalkyl substances and are known as "forever chemicals" because they do not break down in the environment. They are found in many consumer products and have been linked to various health issues, including cancer, thyroid disease, and immune system disorders.

Many brands don't test for PFAS so we penalize 10 points for not testing.

If there are detected PFAS, we dock a 10 point penalty along with the associated contaminant penalties which depend on the exact PFAS and amounts of each detected.


More and more studies are showing the dangers of plastic and the microplastics that leach into the water. We penalize water bottles made of plastic.


  • Plastic: 20

Filtration method

There are several ways to filter water and some filtering techniques can strip water of it's natural minerals which provide our body with essential nutrients. Often a more agressive filtration method such as distillation is a reflection of how dirty the source water is.


  • Distillation: 10


There are several studies showing the ability of alkline water to aide the body in normalizing your PH levels. This essentially means that alkline water can help you maintain a healthy PH level in your body especially if you eat processed foods or drink a lot of alcohol.

We award 5 point bonus if the water as a ph between 8 and 9.

We penalize waters that are too acidic and dock 15 points.

How we score tap water

Tap water is popularly known as a commodity that is safe to drink and available to everyone. However, the quality of tap water can vary greatly depending on where you live and over the years has become increasingly polluted. Each city in the United States is usually supplied by one or more water utlities and we analyze the water from each utility.

When analyzing tap water, we consider the following factors:

  • Unique contaminants
  • Levels of each substance

Unique contaminants

Our database includes all known toxins that can be present in water. We consider anything that isn't beneficial to the body as a contaminant.


  • Unique contaminants: 3.5 per contaminant

Levels of each substance

Not only is the presence of a contaminant important, but the levels of each substance are also crucial. We penalize water for the amount of each substance over the health or legal guideline.


  • Amount over guideline: multiple above / 5

How we score filters

As earth's water becomes more and more polluted, the need for water filters has increased. There are many different types of filters and often it isn't clear which filter is best.

Factors we consider:

  • Number of common contaminants removed
  • Number of uncommong contamianants remove

We weight common contaminants 5 times higher than uncommon contaminants.

Common contaminants

We maintain a list of common contaminants often found in bottled and tap water. These include

  • Bromide
  • Sulfate
  • Total Trihalomethanes
  • Gross Alpha Particle Activity
  • Arsenic
  • Barium
  • Fluoride
  • Nitrate
  • Uranium
  • Bromodichloromethane
  • Chloroform
  • Dibromochloromethane
  • Radon
  • Chloramine
  • Haloacetic Acids (HAA9)
  • Haloacetic Acids (HAA5)
  • Chromium (hexavalent)
  • Nitrite
  • Bromate
  • Bromoform
  • Dibromoacetic Acid
  • Dichloroacetic Acid
  • Chlorine
  • Lead
  • Mercury
  • 1,4-Dioxane
  • Bromochloroacetic acid
  • Beryllium
  • Antimony
  • Selenium
  • 1,2,3-Trichloropropane
  • Bromodichloroacetic acid
  • Radium 226 and 228
  • Microplastics

We take the percentage of common contaminants removed to total common contaminants.

Uncommon contaminants

There are many more contaminants that could possibly be in your drinking water but are much more rare. There are 100s of them so we aren't going to list them all here but you can find the full list on each filter page.


https://www.hsph.harvard.edu/magazine/magazine_article/fluoridated-drinking-water/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6195894/ https://www.cdc.gov/fluoridation/statistics/cost.htm https://bmcoralhealth.biomedcentral.com/articles/10.1186/s12903-018-0684-2 https://www.newsweek.com/fluoridation-may-not-prevent-cavities-huge-study-shows-348251 https://www.sciencedirect.com/science/article/pii/S2666911021000216