HELLO. Let me write you something about unit 4 ; THE TAP WATER.
For a long time we have been listening about  the problems of TAP WATER . In ours country it is a big problems that we have. We don't know what kind of water is good to drink or what isn't.
My  opinion to solve the problem of tap water in our city is educating people to preserve the nature, and not contaminate the enviroment.