Natural water purification

A recent media report indicated a possible new source for potable water in the rural areas of Bangladesh. As far as I could follow, it is done by some naturally found  marshy plants that thrive in polluted water and remove the high levels of unacceptable industrial impurities from the water, making it fit for drinking.
BARI and Dhaka University along with BCSIR may study the matter and set up a pilot project near the industrial area in Dhaka or Chittagong where polluted waste water from plants flow into open natural drains and then onward through canals and streams on to  the rivers.
They can set up a similar project to study the level of natural purification using some natural water plants that can remove detrimental organic and inorganic chemicals polluting the waste waters.
By adopting this process, that may be modified to suit our local availability of such filtering plants and the levels and types of impurities, we may succeed in having drinkable water from rivers and other water bodies that are plentiful in Bangladesh.
This is important, as our water table is shrinking, and the sources of underground access to fresh drinkable water will be a major problem, may be, in ten years' time.
I draw the attention of our scientific community to explore this natural vegetation-based water purification system.

Engr S A Mansoor
Dhaka