Hi Georgina,
Your essay was already on my "to read list" (which is now becoming longer) so thanks for reading my essay and for your excellent question about the more important issue of clean water versus hot water.
In fact in the house of my wife's family, who lives in the rice farming region of Northeastern Thailand close to the Laotian border they do in fact catch rain water in addition to getting water from wells. And the rain water is really great -- it has a totally different, cleaner, better taste compared to the water we have here in the central part of California where I currently live (California is undergoing a severe drought so we would have trouble getting water from rain here, but this rain water solution is definitely workable in some parts of the world, and in fact it is used). To be sure during the dry season in Thailand they use just the well, but during the rainy season they can enjoy water from the sky. One does have to clean the rain water which is caught in this way since they let it run down the slanted roofs (designed for this purpose) and any dirt on the roof will get in the rain water. But they have methods of cleaning the rain water once it is captured in the containers (they have large holding vases for this purpose). Also the dirt issue is largest in the transition between dry and rainy season when the roof has accumulated a lot of dust.
I'll look at your essay soon.
Best,
Doug