Achieving high temperatures, water with high content in bacteria or other harmful microorganisms should be ready for safe consumption. It's lamentable when some areas do not provide the knowledge or tools knowing that drinking water in this state statistically creates premature death at any age, specially in the youngest.
With mirrors, it's possible to focus the Sun's energy to a point to create higher temperatures, perfectly enough for disinfecting the water. The mirror doesn't need to have a specific shape, with a conventional one the effect works. Even without having access to manufactured mirrors, the population of these nearly forgotten areas could start using polished metals to achieve a similar functionality.
It's critical how places that do have an incredible energy input —and of course output— so high cannot be enough organized to use it leaving great problems behind toward a future of prosperity. Yes, is that easy; with Sun, mirrors, water, a magnet and cables it's possible to create a facility to produce electricity. That's the principle behind thermosolar based electric plants. In this case, to disinfect the water and avoiding all that causes, the objective is simpler: boiling water.
If you live in a sunny zone and have this problem, never forget to do the experiment!