The term rain barrel is comes from North America. It means a tank which is used to store rain water. It is nothing but a tank which is generally placed on the roof of a house to store and maintain harvested rain. At this modern age which is known as “age of globalization” the deficiency of pure water is a major factor of humanity. So instead of wasting rain water it can be used in many purposes. It is also cost effective. In this system a tank is present to store the rain water and a filter with a pipe is present there to purify and distribute the stored rain water. A number of tanks with various capacity and prices are available in the market. For home uses a tank with small capacity can be used. The capacity of the tank is generally up to one hundred liter. But in case of big multi stored building, tank with large capacity are generally used to fulfill their purposes. The stored rain water can be used for flushing toilets, washing cars, watering gardens etc. The purified rain water can be used as a drink. But a good quality filtering system must be attached with the tank to make the water safe for us. Because, many germs with many diseases are comes to our body by our drinking water. A number of filtering systems with variable prices are available in the market. In those countries where people buy water for their regular uses, the use of water barrel is important for them to reduce the expenses. A number of companies are present there to serve the total system of storing water with various ranges of prices. At the early age normal barrels which are made by plastic were generally used but now a day the use of fiber bodied tanks become wider. Fiber bodied barrels are more durable and cost effective than ordinary plastic bodied barrels. At this modern age a special type of water barrel is produced which can store a large amount of water and filter the water by electronic device to make it more purified. These types of water barrels are known as flat back water barrel because the back portion of the barrel is flat and rest of the portions are oval shaped. Flat back rain barrel contains a heating system inside the tank. This heater is used to make the water hot to prevent the affection of germs.