I guess the pros would be it's cheaper for the industry to pollute water than it is to treat their waste properly. Industries like mountain top coal mining pollute a lot of water, so it is cheaper for them to pay lawyers to stop any legal actions than it is to find a way to stop water pollution. 

Con's are many. Millions of people are getting sick from tainted water. Ground water is becoming increasingly unsafe and many people don't know the risks until the have irreversible diseases. It costs a lot of money to build and run water treatment facilities. Water needs to be treated before it goes to your house and again after it leaves your house. We are finding that the water isn't treated enough before it is released back into the water system. We have fish and amphibians that are changing gender, high levels of prozac and other pharmaceuticals in fish etc. Even food scraps are changing the ph and nutrient content of our water and adversely affecting water life.

Hope this helps:)