Many of the mansions / houses in and around Chettinad were built-in with arrangements, (the contoured metal sheets placed under the corners where roof tiles of two walls join), for rainwater harvesting, to provide for clean drinking water. The rainwater is [fine cloth] filtered and funneled into large brass-ware that can be stored for weeks. The rainwater being free from [ground] impurities, and by storing it in brass-ware gets some electrical properties, which neutralises [many of the] harmful microorganisms. This provides a clean, healthy, and sweet drinking water that rivals the modern day processed drinking water.
Sadly, this traditional rainwater harvesting become a thing of past!