What role does the Division of Drinking Water play in protecting public health? What is the difference between a Primary and Secondary Drinking Water Standard?

What role does the Division of Drinking Water play in protecting public health? What is the difference between a Primary and Secondary Drinking Water Standard? Why is biological contamination such a great concern in drinking water? How do drinking water systems protect against biological contamination? only use chapters 2 and 3 they should have answers in upload file