Rain water harvesting system is becoming one of the important amenities of all Kochi apartments . This system provides water for basic needs such as washing, bathing, drinking etc. There are concerns about the possible negative health effects of rain water utilization. Objections are raised regarding its use for washing clothes, personal hygiene and even for toilet flushing due to the probable risks of infection and allergic reactions. But long term investigations by the health offices in Hamburg and Bremen have showed positive results regarding the use of water for washing purposes and confirmed that the rainwater sources do not pose a health risk. The storage facility for the collection of the rainwater can be of many types with respect to the shape, size and the material of construction. The shape can be cylindrical, rectangular or square. The material of construction used can be reinforced cement concrete, RCC, ferrocement, masonry, plastic (polyethylene) or metal (galvanized iron) sheets. The tanks can be constructed above ground, partly underground or fully underground depending on the available space. To ensure the quality of water stored in the container maintenance measures like cleaning and disinfection are required to be carried out. Rainwater can also be used to recharge the ground water. It can be charged into the groundwater aquifiers through structures like dugwells, borewells, recharge trenches and recharge pits. Recharge structures are of various types like the ones which promote the percolation of water through strata at shallower depth while others conduct water to greater depths from where it joins the groundwater.