Changes

==Construction, operations and maintenance==

The reason for constructing a sub-surface tank is to store the water. Therefore one of the most important aspects is that seepage and cracks must be avoided. Therefore good quality construction work with adequate supervision is vital to create a sound structure – this is especially important in areas with swelling soils that can affect the integrity of the lining. While ownership and management of tanks is important, such privately-owned tanks have often failed due just to the technical construction component. Construction materials vary and include the natural soil formation itself, clay, stone masonry, bricks/cement, ferrocement, anthill/lime/cement and plastic/rubber lining. Material may affect cost but choice may also depend on what is available and the type of surrounding soil. To generally prevent cracking/seepage:

* Round tanks are inherently stronger than rectangular ones. Hemispherical and cylindrical designs are commonly used.