If I have a borehole with dirty slightly salty water which sequence should I use to get clean water ?

Question

The borehole is at 5 m deep. It is in a 3rd world country on sea side. I collect the water in a tank and treat it with alum. Then I have already a filtering system with sand and active charcoal. I think to add an additional 2 stage small filtration system (200$ thing) but it will it kill the bacterias or remove the salt ? What chemical can I use to kill the bacteria ?
Should I use an inverse osmosis system ? What flowrate can I expect for a 300 $ Osmosis plant ? How often will I need to change the membrane ?

Answer 1

Chlorine will kill the bacteria.

I am not able to tell you about the inverse osmosis system.