Some call it Bladder Tanks, other Pillow Tanks, some other Flexible or Flexitanks. In the end they are massive tanks made of technical fabric to hold various liquids and fluids. They have many usages: - Rain Water Harvesting. - Networks of clean water delivery outlets in disaster zones or humanitarian relief operations. - Emergency reserves for fire brigades. Storing fuels or chemicals. - Farming effluents or or grey and black water. - Milk or wine.