Flexible water tanks for use in production water, rainwater collection, and drinking water applications. In order to provide enough storage capacity for emergency applications, building sites, military facilities, etc., tanks are commonly designed in quantities ranging from 25 to 5,000 gallons. Fabrics certified for use in drinking water and those of food grade are both used in the construction of tanks. The type of water you want to store, the environment (temperatures and storage site), and the amount of time needed for storage all go into the fabric selection process.