There are some significant problems with this as a long-term solution. For instance, sourcing a constant supply of fuel to boil water can be very difficult and expensive. Also, this extra need to constantly burn fossil fuels often leads to higher rates of respiratory conditions.
Boiling the water also does nothing to stop millions of women and children having to walk miles for their water every day, leaving no time for other work or education. Nobody should be forced to live this way. As a long-term solution, it is, therefore more efficient to create a water supply that is close by and clean at its source. This is how we empower communities and eradicate poverty. This in turn, fosters economic independence and growth.