@Eti Thank you for your interest.
A range of natural solutions are available for helping with water treatment processes, such as:
- biological degradation of organic pollutants via plants / micro-organisms
- filtering of particles via slow moving water in wetlands; and
- absorption of toxic heavy metals by plants.
It is unlikely that any one natural solution, alone, can produce potable water (of satisfactory drinking quality). However, it does represent a significant opportunity for producing water for agricultural use, and for use by populations for cleaning and washing activities. It also represents a useful first stage in water treatment processes that do produce potable water.
Producing potable water requires attention to many aspects as illustrated in the WHO’s Guidelines for Drinking-water Quality. This probably illustrates why a group of water treatment processes are typically required. [Although a future radical innovation might change this one day, perhaps using nanotechnology…]
Some natural examples are included below.
Biological Drinking Water Treatment? Naturally
Plants That Remove Contaminants From the Environment
Efficacy of accumulation on heavy metals from aqueous solution using water hyacinth (Eichhornia Crassipes) - water hyacinth was tested for removal of four heavy metals chromium, lead, cadmium, and zinc. Up to 63% of heavy metals were removed.