A bladder tank is a large, flexible container used to store many types of liquids. When maximum capacity is reached, the bladder tank takes the form of a large pillow, hence it is also knows as a pillow tank.

For the use of static bladder storage tanks, installation is fast and simple and only requires a level-, free of sharp objects surface to protect the tank against damage from rocks and or spikes. Ideally a layer of sand or a special ground sheet is used to minimize surface irregularities. Static storage tanks, when used for Fuels or other hazardous chemicals, are usually placed within a berm with a liner for secondary containment to prevent adverse environmental effects when bladder tanks malfunctions. For most non-hazardous applications ground cloths or sheets are used made from geotextile or PVC.