You are right in that some (a lot of the poor people) in India need to access water in rivers n end up bathing there, and that is exactly because of lack of sanitation and basic access to even a toilet in a whole village. But an average indian with a roof on their head - lower middle or middle class uses a bucket and mug through a tap of clean water. That is the practice I am suggesting. Meanwhile if the affluent India and world can stop using bathtubs and showers, perhaps the large underprivileged India, Africa and many other countries will be able to equitably get access to some of those excess resources. That exactly is the point.