"Private Protection Agencies and Courts" are a government. The two cities have set up a court system and a standing police force to resolve the issue. Just because you're using Libertarian words to describe a government doesn't change the fact that a "Private Protection Agency" is a glorified police institution.
FYI, a little global perspective. What happens in "the real world" is that your country loses its rivers and millions die to sewage born illnesses.
http://www.spiegel.de/international/world/dead-rivers-and-ra...
Go fantasize about private protection agencies and courts that don't exist and preach it to the 3rd world. Neither exist in India and millions die to this very problem I've been describing.
Perhaps if you stopped believing in pure theoretical fairy tales (wtf? Private Protection Agencies? They don't even exist.) and looked at real world problems, you'd know.
The Ganges river has 2 Million people ritually bathing in it every day due to Hindu tradition. It has over 400 Million living by it as a potential source of drinking water... and it carries some 80% of the Indian untreated sewage.
Tell me, how long will it take for a "Private Protection Agency" and "Court System" to stand up automatically in those Indian villages? People don't even understand the concept of pollution. The reality is, "City Downstream" may not even know that "City Upstream" is the cause of their problems.
India's government isn't powerful enough to create a solution. The current situation, is as "free market" as it gets. Lets see how long before someone comes up with a solution, or for your fairy tail "private courts" to be set up.
Yes, NGRBA was set up in 2009 to fix the problem. The "Free Market" had over 20 years to solve this pollution problem. Guess what? Externalities can't be solved by the free market. At very least, not before the 20+ years it takes to convince a government bureaucracy that there is a problem.