what does it infer from the statement " but gandhi wasn't permitted to draw water from the well lest some drops from his bucket pollute the entire source;how did they know that he wasn't an untouchable?"xplain
This line means that the servants of Rajendra Prasad did not allow Gandhiji to draw water from the well in case that one drop of water from his bucket pollutes the entire well. They could not identify him with his status from his outer appearance. There was no sign from which they could recognise that he was not an untouchable.
Once, Gandhiji went to meet Rajendra Prasad along with a peasant called Shukla. Rajendra Prasad was out of town and his servants did not recognize Gandhiji, from his simple dress, plain living manner and also his poor companion Shukla. They thought him to be an untouchable. They took Gandhiji to be another peasant. So, they did not allow him to draw water from the well as they thought that one drop of water from his container would damage the whole well.
Once, Gandhiji went to meet Rajendra Prasad along with a peasant called Shukla. Rajendra Prasad was out of town and his servants did not recognize Gandhiji, from his simple dress, plain living manner and also his poor companion Shukla. They thought him to be an untouchable. They took Gandhiji to be another peasant. So, they did not allow him to draw water from the well as they thought that one drop of water from his container would damage the whole well.