EDIT: Clean water and Sanitation does not necessarily prevent Polio. Consider the outbreak in the US. People were "too clean" and the children were not exposed to the virus in order to develop antibodies.
"Polio epidemics first appeared in the mid-nineteenth century. Many doctors and scientists struggled with the mystery: why, as living conditions improved, did incidents of paralysis increase? Out of all the changes that came with modernity, improved sanitation was chosen as the change which caused polio to turn from a mild illness to one that left death and permanent damage in its wake.
Here is an excellent example from a 2007 medical article which summarizes the concept:
Prior to the 20th century, virtually all children were infected with PV while still protected by maternal antibodies. In the 1900s, following the industrial revolution of the late 18th and early 19th centuries, improved sanitation practices led to an increase in the age at which children first encountered the virus, such that at exposure children were no longer protected by maternal antibodies. Consequently, epidemics of poliomyelitis surfaced."
Also, vaccines can cause Polio:
"Provocation polio due to vaccines or other injections: the third item on the chart of types of acute flaccid paralysis is “vaccine-associated paralytic poliomyelitis.”  Yes, vaccines can cause paralytic polio. In fact injections of many different drugs such as anesthetics, Antibiotics , etc, can cause paralytic polio"
India has had high rates of Polio. During the 80's and 90's when thousands of cases were documented, (150,000 a year in the '80s) only about 1 percent of India's population had access to clean water and sewage treatment.
Basically, nothing was accomplished by the government until 1999 when an initiative was introduced to eradicate open defecation. (It might help if people would stop crapping any place they so desired.) It was not until 2000 that the government started monitoring the water!
In 2002, India still dominated the world in cases of Polio. In 2002, the Indian government decided to make access to clean water for the rural areas a priority. Also the government started teaching hygiene to the people.
Notice how the cases of Polio dropped when clean water became a priority. In 2001 clean water was available to about 68% of the people. Today, clean water is available to about 90%.(Sewage treatment is still low.)
The polio vaccine program has been in progress for the last ten years which coincides with the improvement in water access and sanitation from 2001-2002 to 2011.
There are still major problems with the water supply contaminated with arsenic, fluoride, pesticides and industrial waste. Al least within the last decade the government has taken a more active approach.
Cleaner water may have also contributed to lowering rates of polio. "The need for user involvement in maintaining water quality and looking at other aspects like hygiene, environment sanitation, storage and disposal are critical elements to maintain the quality of water resources."
The polio effort became a cult like agenda with everyone involved including religious leaders and Celebrities. "You're talking about community leaders, religious leaders, academic leaders, opinion leaders, so just getting -- really turning it into sort of a national movement, so that everybody feels that they are part of this movement."
It is pure insanity. In India, 40 children die an hour from Diarrhea before the polio has a chance to take hold. "A drop of vaccine? Why can't you reach us with education and health and good water and sanitation?" Why not attack the cause of the polio in the first place? It is crazy world. Everything is ass backwards.