In 2005, I visited a boarding school in Pontianak, Kalimantan, Indonesia. I followed a church group who were visiting the school. My role was to study if it is possible to help them make their well water drinkable using a simple water filter system. I brought water samples back for testing and found that the water was acidic. This requires an additional process of neutralisation to raise the pH level of the water to 7.0 before filtering.
Also notice that the water was greenish in the toilet and latter realise that it was due to the acidity in the water attacking the copper pipes.
I did not recommend to install a simple water filter system as they need to address the low pH first.
