Green-Tak Rainwater Harvesting Water Filtration is durable and excellent performance water purification system for river water, rainwater and other surface water to purify for daily domestic water use and even potable water. The gravity membrane is NSF certified, FDA certified, SGS certified and even tested and approval by SUPER LAB for remove rate up to 99.98% for V. Cholerae and is the best quality gravity water filtration system. Features No power consumption, environmentally friendly. High Flow Rate Capacity. No wastewater. Washable and Easy maintenance by residents. High Filtration Performance. Long Term membrane and filters lifetime.