The Otterpack is a portable, energy-independent water purification system utilizing reverse osmosis technology. Designed for easy transport as a backpack, it can purify up to 120 liters of water per hour from various inland sources, including brackish water with salinity up to 2,500 ppm. The system operates either manually, by rotating a handle, or electrically, using a rechargeable battery, vehicle accumulator, or solar panels.