Hey Napas,
This is such a great idea that could benefit not just people in Thailand but every regions around the world. I love the idea of how this rain water catchment will be filter and eventually become drinkable water for people within a household. Furthermore, I believe if this idea get expert feedback and push a little further together with adding a little more design - this idea can become a structure which can be place anywhere around the city so everyone can access and contribute to it.