Rainwater Tanks For Water Storage
There are several factors that determine the design of Rainwater tanks to be installed at any place. Volume of the tank is one of those factors. Given below are the factors that determine the required volume of the tank:
• Number of members in household: If there are more people, there will be needed more storage capacity so that same efficiency can be achieved as in case where there are fewer members in the same household area.
• Water required per capita: Depending upon seasons and habits of people residing in differing households, requirement of water per capita also differs. The duration for which rainwater stored in a particular rainwater tank lasts and also the design of the storage system are greatly affected by the rate of consumption of water by consumers in one household.
• Average rainfall per year.
• Water scarcity period: Storage requirement will not only be determined by the total rainfall in a year but also by rainfall pattern. Pattern of rainfall can be either concentrated in some periods or may be distributed evenly throughout the year. In latter case, size of storage can be less.
• Catchment size and type: Size of the tank should be according to that of the rooftop for a larger catchment area requires bigger size of tank. Besides, type of material used in roofing also plays an important role for selecting runoff coefficient.
Demand v/s supply approach (in dry season):
To determine storage volume, one has to consider the following three options:
• Bringing together the area of the rooftop and capacity of the rainwater tank.
• Bringing together the required quantity of water and capacity of the rainwater tank.
• Analyzing whether the tank size chosen is economic and worth in terms of construction methods and resources.
Generally the above given factors i.e. construction methods, resources and cost, only tend to limit the size of Rainwater Tanks to be chosen which could be else justified by other factors like consumer needs and rooftop areas. This restricts you from messing up with elaborated calculations as it would be only useless. For safer side one should go for a tank size that is 25 percent greater than needed (approximately 14700 l). This size is ideal for storing drinking water for a household comprising of five members during dry seasons. If the tank is to be built in the basement, ideal size would be around 4m x 4m x 1m.
• Number of members in household: If there are more people, there will be needed more storage capacity so that same efficiency can be achieved as in case where there are fewer members in the same household area.
• Water required per capita: Depending upon seasons and habits of people residing in differing households, requirement of water per capita also differs. The duration for which rainwater stored in a particular rainwater tank lasts and also the design of the storage system are greatly affected by the rate of consumption of water by consumers in one household.
• Average rainfall per year.
• Water scarcity period: Storage requirement will not only be determined by the total rainfall in a year but also by rainfall pattern. Pattern of rainfall can be either concentrated in some periods or may be distributed evenly throughout the year. In latter case, size of storage can be less.
• Catchment size and type: Size of the tank should be according to that of the rooftop for a larger catchment area requires bigger size of tank. Besides, type of material used in roofing also plays an important role for selecting runoff coefficient.
Demand v/s supply approach (in dry season):
To determine storage volume, one has to consider the following three options:
• Bringing together the area of the rooftop and capacity of the rainwater tank.
• Bringing together the required quantity of water and capacity of the rainwater tank.
• Analyzing whether the tank size chosen is economic and worth in terms of construction methods and resources.
Generally the above given factors i.e. construction methods, resources and cost, only tend to limit the size of Rainwater Tanks to be chosen which could be else justified by other factors like consumer needs and rooftop areas. This restricts you from messing up with elaborated calculations as it would be only useless. For safer side one should go for a tank size that is 25 percent greater than needed (approximately 14700 l). This size is ideal for storing drinking water for a household comprising of five members during dry seasons. If the tank is to be built in the basement, ideal size would be around 4m x 4m x 1m.
