The amount of rain received by different regions in India varies. Due to scarcity of water it has become important to save as much water as possible. The rain water harvesting system used in each part varies depending upon the resources available. Each Kerala apartment is now making an attempt to use the best rain water harvesting system to save maximum water.
 
In Kerala, temporary dams stretching across the mouth of channels is called Korambu or chira. It is generally made of brushwood, mud and grass. The dam is constructed by horizontally fixing a strong wooden beam touching either banks of the canal. A number of vertical wooden beams of appropriate height are erected while their lower ends rest firmly on the ground and the other end tied to the horizontal beam. To this frame closely knitted or matted coconut thatch is tied. On this matted frame a coat of mud is applied. To prevent the dissolution of the applied mud a layer of grass is also applied carefully. The dam is constructed to raise the water level in the canal and divert the water into field channels. The dam is built in such a way that the excess water flows over it and only the required amount of water flows into the diversion channels. The height of the Korambu is adjusted such that the fields lying on the upstream are not submerged. Until all the fields are irrigated, water is allowed to flow from one field to another. They are built before the onset of the monsoon season, twice a year, in order to supply water during winter and summer season.