Why dilution is not a solution of pollution control?

what "The key to pollution is dilution." means you do less of what is said "pollution" to solve it. I was given the example "if you beat someone with a stick it is abuse, but if they beat me with something less deadly (their hand) it will not be abuse."

So if u add water to waste it becomes less percentage (%) waste and more diluted. This then becomes less "pollution." So it does solve the problem, by definition.