Water shortage is becoming an acute problem, particularly in under developed regions of the world due to added demands of an ever rising population. Poor water management, unclear laws, government corruption and industrial and human waste have caused this water supply crunch and rendered available water practically useless due to the huge quantity of pollution. Supply of water is rapidly dwindling primarily due to mismanagement of water resources, although over-pumping and pollution are also significant contributors. Climate change is expected to exacerbate the problem by causing erratic and unpredictable weather, which could drastically diminish the supply of water coming from rainfall and glaciers. Water shortage could lead to a slew of subsequent problems such as food shortages. Ground water resource gets naturally recharged through percolation. But due to indiscriminate development and rapid urbanization, exposed surface for soil has been reduced drastically with resultant reduction in percolation of rainwater, thereby depleting ground water resource. Rainwater harvesting is the process of augmenting the natural filtration of rainwater in to the underground formation by some artificial methods. Rain water harvesting is essential because surface water is inadequate to meet our demand and we have to depend on ground water and because recharging of ground water has diminished. There are two main techniques of rain water harvestings. • Storage of rainwater on surface for future use. • Recharge to ground water. Rain water is being harvested/used instead of wasting it through soil percolation. Water so collected, is now used for WCs, washing machines or garden irrigation. This can save both valuable potable water and expensive wastewater charges. Compared with concrete tanks, tanks in plastic that are easier to instal and handle can be used. Because of the much lower weight, installation cost comes down. Tanks can either be rotational molded or produced in the form of clamshell halves and stapled on palettes. The later method has a lower transport cost along with easy logistics. Smooth tank inner surfaces prevent build-up of contamination, thereby enabling high water quality and simultaneously easy tank cleaning. The tanks have long life and can be recycled after use. Types of water storage tanks include: Surface Storage: Free-standing plastic tanks offer the least expensive means of rainwater storage and are available in a wide range of sizes. Since they simply sit on compacted fill or a concrete base, installation is relatively simple. But plumbing and pre-filtration can be problematic when surface tanks are used for large roofs with multiple downspouts. Without expensive insulation systems, surface tanks must be drained for the winter in cold climates. In hot humid climates where nighttime temperatures do not drop significantly, water stored in surface tanks can get quite warm, leading to accelerated biological activity. Since surface tanks are exposed to the weather, they have finite life spans that must be factored into the cost evaluation. Large surface tanks are very difficult to conceal, although sometimes they can be incorporated as a dramatic building design element. Underground tanks: They are invisible, are unaffected by freezing weather, and can last indefinitely. Since underground tanks provide a cool, dark environment inhospitable to algae and microbial growth, they are always preferred when rainwater is to be reused inside buildings. On the other hand, underground storage is usually two to three times as expensive as surface storage and involves significant excavation which can be problematic for sites with large rocks or high groundwater. Typical underground plastic water storage tanks are simply septic tanks made with FDA grade plastics and re-labeled as cisterns. While these tanks may work well as holding tanks for low-yield wells, or as holding tanks for fire control, most are not sufficiently strong to remain empty for any period of time and are not suitable for rainwater storage systems. We offer a range of underground tanks suitable for rainwater storage, each of which has been engineered to remain empty indefinitely without risk of collapse. Most also include specialized features for rainwater collection such as access ways large enough to accommodate filters, pumps and controls and provision for large diameter ports both top and bottom.