TECHNOLOGY & APPROACH
Gravity Water focuses on a low-technology approach to safe drinking water access through combining rainwater harvesting, elevated storage, and gravity-fed filtration.
Why Rain?
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Did you know the vast majority of people who don’t have access to safe drinking water around the world live in the Tropics and Sub-tropics? 2 billion people around the world still depend on a contaminated water source, even though the majority live in places where fresh water is abundant. The problem that most communities face is not a lack of access to fresh water, but water pollution and contamination (most commonly from sewage and fecal bacteria), making the water they have unsafe to drink.
The Earth has been filtering water for billions of years through the “water cycle”, turning water on the Earth’s surface and in the ocean’s into fresh rainwater through evaporation and condensation. Unlike groundwater, rainwater isn’t at risk of significant contamination until it reaches the ground where most harmful pollutants exist; this is why the World Health Organization considers rain an “Improved Drinking Water Source”, opposed to unprotected wells and surface water. Since fecal bacteria from human waste isn’t commonly found on roofs, rainwater harvesting and sterile storage largely prevents contamination from taking place. |
Elevated Storage
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Energy-free Storage: Gravity Water's systems store rainwater approximately two meters (six feet) above ground, providing potential energy for filtration through using gravity. In contrast, nearly all groundwater and surface water sources require electricity to raise the water above ground level or create pressure for filtration.
Long-term Water Storage: Storing rainwater allows people to utilize individual rain events for extended periods, providing localized fresh water access from months to whole seasons. Many areas around the world, such as the tropics, undergo seasonal or year-round rainfall patterns. Gravity Water works with each community to help them meet their water consumption needs, year-round. |
Treatment + Prevention
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Starting with Safer Water: The World Health Organization considers rainwater an improved drinking water source, since it is captured before it comes into contact with many of the ground-level pollutants that cause the majority of water-related disease. Gravity Water takes the extra step in safety by filtering this water to ensure user confidence and experience.
Filtration Methodology: The Gravity Water tank system uses a three-tier filtration system. Pre-filtration takes place using two 5-micron activated carbon block filters, which removes any odor and taste associated with the water, ensuring good user experience comparable to drinking bottled water. These filters also remove macro pollutants, such as sediment, parasites, and many chemicals and metals. After the two-stage carbon block filtration, the water passes through a final stage 0.1-micron hollow-membrane water filter, which removes 99.99999% of any bacteria and meets U.S. EPA standards for private consumptive use. |
OUR PRODUCT AND SERVICE
Gravity Water systems provide decentralized, "stepping-stone" technology for schools that lack access to improved water sources.
Traditional Gravity Water System
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Gravity Water system with handwashing station add-on
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The Gravity Water System is a decentralized rainwater harvesting and filtration system that provides access to improved water, on-site.
Gravity Water Systems serve as "Stepping Stone" technology for schools that lack access to an improved water source, ensuring reliable and long-term clean water access that can be instantly deployed in urban or rural areas for a fraction of the cost of advanced treatment systems.
Gravity Water Systems serve as "Stepping Stone" technology for schools that lack access to an improved water source, ensuring reliable and long-term clean water access that can be instantly deployed in urban or rural areas for a fraction of the cost of advanced treatment systems.
Gravity Water System Specifications
Gravity Water Systems come in three models, depending on school size and access to fresh water.
System Size |
Rain Storage |
Filtered Water Storage |
School Size |
Gravity Water Mini |
2,000 L |
500 L |
up to 200 students/day |
Gravity Water Standard |
3,000 L |
500 L |
200-300 students/day |
Gravity Water XL |
5,000 L |
1,000 L |
300-500 students/day |
- Each system is standardized with the option of add-ons, such as extra rainwater storage, hand washing stations, or additional filtration packages.
- Each system has an average filtration rate of up to 1,400 liters per day.
- Average system pricing ranges from $1,000 USD - $3,500 USD, depending on location, model, and required add-ons.
- Average recurring costs range from $75 USD - $100 USD per year ($0.15 - $0.50 USD/person/year), primarily for filter replacements.