Numerous studies have been done on Moringa Oleifera seeds and their ability to clean water. Here is the latest study conducted by Penn State.
There is a water treatment plant in Thyolo Malawi that uses Moringa seeds with great success and at a much lower cost than chemicals.
The great thing about Moringa Oleifera is:
1) It's native to India.
2) It grows extremely fast so it can be scaled up at a low cost.
3) The leaves and seeds have proven anti-parasitic properties (which goes hand in hand with dirty water).
4) It's also considered to be the most nutritious plant on earth (but that's a subject for another OpenIDEO challenge).
There are a number of nonprofit or for profit ways to proceed. The general idea is for a local Indian company to teach families how to use the crushed Moringa seeds to clean their water, and distribute (nonprofit) or sell (for profit) packets of crushed Moringa seeds so families can use the packets to purify their water. If possible, while doing so, they can also teach families how to use Moringa seeds and leafs as anti parasitic medicine.