But sometimes even city water can get polluted, especially after heavy rains. A pipe can also break underground, letting dirt into the water. Even in places where there are systems to chlorinate the water and kill germs, the water is not always safe because sometimes the machines to do this are not taken care of or break down. The other big problem with water is getting enough of it when there is too little rain. Wells can get polluted, become salty, or dry up entirely.
Cisterns are empty.
Streams stop flowing, especially if the land upstream has been developed or the forest cut or burned. Water for essential uses may have to be brought from far away. People cannot wash as much and they must live in dirty surroundings, so more of them get sick. Industries using water may have to shut down, putting people out of work. If you know your water is dirty, or if people, especially children, are getting sick, it is not hard to make water safe to drink.