I am very interested in the rain water collection system which is an environment friendly design application.
I am in my thesis year right now, and would like to know more about these systems. James
"Environment friendly" is based on comparison of the value of the product to the cost of all resources (materials, labor, energy, and negative impacts caused by the activity) necessary to deliver an economically useful product. In an economic system such as we have in the United States, all of those things can be normalized to cost. Cost is a measure of the total resources that must be diverted from something else to accomplish an objective.
Everything should be reduced to cost per unit of water collected and applied to use,and that cost per unit of water should be compared to the cost for water from other sources and the value that is returned for the eventual use of that water.
If you are writing a thesis you can easily create a model of the water collection system, including the economics of the system, using Excel or other computer program.
Get the actual rainfall data for a few areas, develop a conceptual design for collection area and storage system, account for evaporation losses which you can find on the internet, and calculate the capital and operating cost for collection, storage, treatment, and delivery of the water.
Then calculate the cost per unit of water delivered, and the economic value of that water for some purpose, and compare it to the cost and economic value for alternative sources of water. The economic value of drinking water is greater than the economic value of water to irrigate a field of alfalfa.
When you get through with the project you should be able to publish conclusions, supported by analysis, of the climates and conditions for which rain water collection is the best (meaning most economical) means of supplying needed water that has some economic value.
Economic value exists only if someone is willing to pay more for the water than it costs to produce it.