There is no danger of the water being contaminated if it is filtered prior to entering the tank. The tank is a closed system, so it would be impossible for mosquitoes to gain access.
You can see how if this was applied to an industrial area with all that flat space, how much rainfall could be saved.
There are 1.6 billion people in the world who do not have access to drinking water. Think about Mexico. Its water is almost brown. You can't drink it.
Everybody knows that people like spending money on helping the environment.
