How Scoring Works

Overview

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 its 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:

• Contaminants
• Lab verified
• Source
• PFAS
• Packaging
• PH

Contaminants

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

Penalties:

• Contaminant severity score (1-5) * amount over health guideline
• Max penalty per contaminant: 60
• No lab report: 25

Lab verification

Bottled water without a verified lab report is penalized 60 points to account for any contaminants that may be present.

Source

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 treatment to remove the countless toxins inside. This treatment strips water of its natural minerals, making it harder for the body to digest and often adds disinfectant by-products to the water.

Other sources 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.

Penalties:

• Municipal water supply: 15
• Rain: 10
• Spring: 0
• Aquifer: 0
• Unknown: 15

Packaging

The container a water is stored in greatly impacts its quality as contaminants can leech into the water from packaging..

Penalties:

• Plastic: 15
• Can: 10
• Aluminum: 10
• Cardboard: 10
• TetraPak: 10
• Glass: 0

PFAS testing

PFAS (perfluoroalkyl and polyfluoroalkyl substances) are a class of chemicals that are very common in water sources across the United States and are highly toxic. No amounts of PFAS are recommended for consumption. This is an added penalty in addition to the one it receives in the contaminant scoring.

Penalties:

• Untested for PFAS: 10
• Tested for PFAS: 0

Microplastic testing

Bottled water tested for microplastics receives a bonus of 5 points.

How we score tap water

Tap water quality varies significantly by location and is evaluated based on the contaminants present in the water supply. Our scoring system takes into account both the number of contaminants and their levels relative to health guidelines.

Scoring Components

The tap water score starts at 100 and is reduced based on two main factors:

• Number of contaminants present (5 points per contaminant)
• Amount of each contaminant above health guidelines

Contaminant Penalties

For each contaminant, we calculate penalties based on:

• The amount of the contaminant divided by its health guideline (or legal limit if no health guideline exists)
• Each contaminant can receive a maximum penalty of 45 points
• The total penalty is divided by 2 to create a more balanced score

Score Normalization

To ensure scores remain meaningful and comparable:

• Scores are normalized to fall between 1 and 100
• If a score would fall below 20, it's adjusted using a ratio-based calculation to maintain meaningful differentiation
• The final score is rounded to the nearest whole number

Important Note: Tap water scores are not directly comparable to bottled water scores. While tap water might receive a score of 30 and bottled water a score of 25, this does not necessarily mean the tap water is better. Bottled water typically undergoes more rigorous testing and filtration processes, and tap water scores are evaluated on a different scale to account for its unique characteristics and testing limitations.

Our scoring system provides a comprehensive evaluation of tap water quality, taking into account both the presence and concentration of contaminants. This helps consumers understand the relative safety of their local water supply while acknowledging the inherent differences between tap and bottled water evaluation methods.

How we score filters

As Earth's water becomes more and more polluted, the need for water filters has increased. We analyze the testing report of each filter to determine its effectiveness in removing various contaminants. Our scoring system takes into account both the percentage of contaminants removed and the relative importance of each contaminant category.

Contaminant Categories and Weights

Each contaminant category is assigned a weight based on its potential health impact and prevalence. Here are the main categories we evaluate:

• Heavy Metals (9.68%)
• Chemical Disinfectants (8.06%)
• Volatile Organic Compounds (VOCs) (8.06%)
• Microplastics (6.45%)
• Pesticides & Herbicides (6.45% each)
• Perfluorinated Chemicals (PFAS) (9.68%)
• Radiological Elements (9.68%)
• Microbiologicals (9.68%)
• Haloacetic Acids (4.84%)
• Trihalomethanes (4.84%)
• Fluoride (4.03%)
• Semi-Volatile Compounds (4.03%)
• Pharmaceuticals (3.23%)

Scoring Calculation

The filter's score is calculated using the following formula:

• For each contaminant category, we multiply the percentage of contaminants removed by the category's weight
• These weighted scores are summed to create the final score
• The score is normalized to ensure it falls between 1 and 100
• Categories with incomplete or missing test are rated based on the filtration technology used but receive a penalty of 50%

For example, if a filter removes 90% of Heavy Metals (weight: 9.68%), 80% of VOCs (weight: 8.06%), and 100% of all other categories, it would receive a high score. Conversely, a filter that performs poorly in high-weight categories like Heavy Metals or PFAS would receive a lower score, even if it performs well in lower-weight categories.

This weighted scoring system ensures that filters are evaluated based on their effectiveness in removing the most critical contaminants, while still considering their overall performance across all categories.

How we score shower filters

Shower filters are evaluated based on their effectiveness in removing various contaminants from water. Our scoring system takes into account both the percentage of contaminants removed and the relative importance of each contaminant category.

Contaminant Categories and Weights

Each contaminant category is assigned a weight based on its potential health impact and prevalence. Here are the main categories we evaluate:

• Heavy Metals (15%)
• Chemical Disinfectants (20%)
• Volatile Organic Compounds (VOCs) (12%)
• Microplastics (10%)
• Nanoplastics (5%)
• Perfluorinated Chemicals (PFAS) (10%)
• Microbiologicals (8%)
• Semi-Volatile Compounds (8%)
• Haloacetic Acids (6%)
• Trihalomethanes (6%)
• Pesticides (6%)
• Herbicides (6%)
• Fluoride (7%)

Effectiveness Scale

Each category is rated on an effectiveness scale:

• Poor: 25 points
• Good: 70 points
• Very Good: 80 points
• Excellent: 100 points

Scoring Calculation

The filter's score is calculated using the following formula:

• For each contaminant category, we multiply the effectiveness score by the category's weight
• These weighted scores are summed to create the final score
• The score is normalized to ensure it falls between 1 and 100
• Filters with lab-verified results receive a bonus of 10 points

For example, if a filter has excellent (100) removal of Heavy Metals (15% weight), very good (80) removal of VOCs (12% weight), and good (70) removal of all other categories, it would receive a high score. The final score would be adjusted based on the weighted performance across all categories, with the lab bonus added if applicable.

This weighted scoring system ensures that shower filters are evaluated based on their effectiveness in removing the most critical contaminants, while still considering their overall performance across all categories.

How we score drinks

Our scoring system for drinks evaluates various factors that impact health and safety. Each drink starts with a base score of 100, and points are deducted based on several key factors.

Harmful Ingredients (0-85 points)

The most significant factor in scoring drinks is the presence of harmful ingredients and contaminants. Each harmful ingredient is penalized based on:

• The severity score of the ingredient (1-5 scale)
• The amount of the ingredient relative to health guidelines
• Maximum penalty per ingredient is capped at 5x the severity score
• Total harmful ingredient penalties are capped at 85 points

Lab Verification (0-10 points)

Products without verified lab reports receive a 10-point penalty. This ensures transparency and accountability in product testing.

Packaging (0-5 points)

The type of packaging can impact the safety of the drink. Points are deducted for:

• Plastic packaging: 5 points
• Aluminum cans: 5 points
• Cardboard packaging: 5 points
• Glass packaging: 0 points (no penalty)

The final score is calculated by subtracting all penalties from 100. The minimum possible score is 1, ensuring that even products with multiple issues receive a score that reflects their relative safety.

This scoring system helps consumers make informed decisions about their beverage choices by considering multiple factors that impact health and safety.

How we score food

Our scoring system for food items (including supplements, snacks, and other food products) evaluates various factors that impact health and safety. Each food item starts with a base score of 100, and points are deducted based on several key factors.

Harmful Ingredients (0-85 points)

The most significant factor in scoring food items is the presence of harmful ingredients and contaminants. Each harmful ingredient is penalized based on:

• The severity score of the ingredient (1-5 scale) is doubled for food items
• The amount of the ingredient relative to food-specific health guidelines
• Maximum penalty per ingredient is capped at 5x the severity score
• Total harmful ingredient penalties are capped at 85 points
• Beneficial ingredients are tracked but do not directly affect the score

Lab Verification (0-10 points)

Products without verified lab reports receive a 10-point penalty. This ensures transparency and accountability in product testing and ingredient verification.

Packaging (0-5 points)

The type of packaging can impact the safety of the food product. Points are deducted for:

• Plastic packaging: 5 points
• Aluminum cans: 5 points
• Cardboard packaging: 5 points
• Aluminum packaging: 5 points
• Glass packaging: 0 points (no penalty)

The final score is calculated by subtracting all penalties from 100. The minimum possible score is 1, ensuring that even products with multiple issues receive a score that reflects their relative safety.

This scoring system helps consumers make informed decisions about their food choices by considering multiple factors that impact health and safety, with particular attention to food-specific health guidelines and ingredient severity.

Open Source Rating System

Our rating system is open-source and based on the latest scientific research. We believe in complete transparency in how we evaluate products, and we welcome community feedback to help improve our methodology.

As new scientific evidence emerges and our understanding of water quality evolves, our rating system may be updated to reflect these changes. We are committed to staying current with the latest research and best practices in water quality assessment.

If you have suggestions for improving our rating system or would like to discuss specific aspects of our methodology, please don't hesitate to contact us. We value the input of our community in making our rating system as accurate and helpful as possible.