There are two important aspects to untouchability -- poverty and lowly tasks.

People (especially the “untouchables”) end up being excluded from the social mainstream because of their poor economic condition. The best solution to this problem is to help poor people (including by Govt.) according to their economic condition (poverty line or limit) rather than their caste (ancestors’ occupation) or religion (where, how and to whom people pray).

Moreover, the work performed by poor people (including the untouchables), even though very important to society, is usually manual and menial and it is considered by others as lowly. People, usually the well-to-do, try to shy away from such lowly work and also shun those doing it. The effective solution to this problem is to bring a change in the attitude of people so that they don’t mind undertaking manual and menial tasks and don’t shun the workers engaged in such tasks.

Thus there is a need for important people in society, including ministers, politicians, leaders, officials etc., to carry out public demonstrations (in front of the media) where they engage in cleaning the public toilets and washrooms and sweeping the roads and streets. This will quickly get rid of the taboos about manual and menial work and end discrimination according to occupations.

Ref.: Subhash C. Sharma, "Some questions (comments) related to Hindu Caste System," 2011 (Appendix), http://creative.sulekha.com/some-questions-comments-related-to-hindu-caste-system_595419_blog

A blog related to this,
"Aiding the society as a janitor (bhangi)", 2003, http://www.geocities.ws/lamberdar/dalit.html

An excerpt in the following from "In pursuit of clean and hygienic surroundings" (Subhash C. Sharma, 2009) -- http://www.geocities.ws/lamberdar/slum.html

"Thus it is necessary to bring an immediate change in the attitude of public, religionists and government officials so that the situation related to cleanliness and sanitation can be improved. To this effect, public and officials, who in the past probably were never involved in the cleaning of washrooms etc. and therefore now lack proper understanding in the problems related to sanitation, need to be exposed to such issues. This will need them to acquire important knowledge and training firsthand, preferably through actual participation in cleaning. As a result, they will know the value of such work and even appreciate it. It will also help them to become self-reliant in such tasks and make them realize that manual work is very important and not really lowly and worth shunning. Furthermore, when public officials get involved in such work and become knowledgeable about it, they will be able to make proper decisions and implement effective policies on such issues. Similarly, if politicians, officials and public figures engage in the work of cleaning and sanitation enthusiastically in front of ordinary citizens, it will lessen shame and reluctance among people against such work and even enhance respect and appreciation for those doing it already and making an important contribution to society through such activities (1).

"Realizing also that government sponsored reservations and quotas in education and jobs are geared mostly towards office type careers and they hardly give any incentives to manual jobs, government may instead recommend an increase in the remuneration paid to manual workers for the jobs they are doing (e.g. in cleaning and sanitation work). This will improve the financial condition of these workers and help them acquire a better standard of living. Furthermore, emphasis on the part of public and officials should be on trying to make the jobs of cleaners etc. easy, simple, safe and even mechanized. In this regard, they must ensure that there is sufficient water for cleaning and that the latest technological gadgets and tools including latex gloves etc. are available for doing such work. This will lead workers to do the cleaning jobs properly and they will not have to touch and handle filth and hazardous waste with their bare hands etc.

"As the work related to sanitation and cleaning becomes refined due to above changes and it results in a better life, more money and respect for workers, there will be a change in the attitude of public towards them and their vocation. Moreover, as their economic condition improves due to higher wages for their work, they might even be able to send their children for any type of education and career on their own without requiring government assistance. Similarly when the ordinary people become aware about the importance of sanitation and realize that the work related to it is not difficult or something to be ashamed of, and can even be quite rewarding financially, they might also be drawn to it rather than shun it as was the case before. This has the potential for a healthy change in society in encouraging people to do manual work, including in cleaning and sanitation. This will lead to a bigger workforce ready to do all kinds of manual tasks.

"Therefore it is time for officials and politicians to take lead and emphasize the need for improved sanitation and cleanliness leading to a better environment. They can do this by demonstrating to public that they are ready to take hands on approach to set things right and even willing to clean and maintain a public toilet nicely in front of media and people, especially the citizens in their own area or constituency. Needless to say, such cleaning demonstrations by public officials and politicians will bring a rapid change in the attitude of ordinary citizens and inspire them to do the same at home and outside. This will also give a great insight to everyone, decision makers and policy setters especially, in problems and issues related to poor sanitation, filth and sewage, and that will eventually help in finding the easy, practical, quick and cheap solutions (2)."

Before society got stratified into castes and sub-castes on the basis of occupations and birth, things were quite open and flexible all around in the beginning.

Everyone long ago seemed to be trying to earn a living in whatever way possible, according to 'karma' (or the task to be done) as well as one's own 'guna' (or capability / qualification), as implied in the Bhagavad Gita (Ch. 4 - V. 13).

In addition, according to the Veda (http://www.geocities.ws/lamberdar/_caste.html),

"We all possess various thoughts and plans and diverse are the callings of men. The carpenter seeks out that which is cracked, the physician the ailing, the priest the worshipper......." (Rig Veda: Book 9, Hymn 112.1);

"I am a bard, my father is a physician, my mother's job is to grind the corn......" (Rig Veda: Book 9, Hymn 112.3).