Water supply

In inquiry we are looking at water supply. Some people have no choice but to drink dirty water and they can get really sick. People in Afghanistan have to fetch their water and some villages have to fetch their water from water holes or a river. For example in Kroo Bay in Africa all the water is dirty so they have to drink it. Some countries have only dirty water so they can't drink it with out getting really sick. What can we do to help them?