In those days there used to be a Nahar(canal) in Chandni Chowk and because of the Nahar, his family became to be known as Nehru.

Maybe!!

Nehru family fundamentally had a place with Kashmir. Jawaharlal Nehru in his life account "Meri Kahani" has composed that Farrukhsiyar( He was simply the Mughal ruler somewhere in the range of 1713 and 1719) himself has gotten his family to Delhi late 1716 and settled there. In those days there used to be a Nahar(canal) in Chandni Chowk and on account of the Nahar, his family progressed toward becoming to be known as Nehru. 

Prior to the revolt of 1857, Jawaharlal Nehru's granddad Gangadhar Nehru was a Kotwal of Delhi in the rule of Bahadur Shah Zafar. In any case, when students of history investigated they found that city's Kotwal was a significant position like the present police magistrate and such significant positions were just offered to Muslims and basically to their very own Muslim posterity. A Hindu to be delegated to such a significant position was not under any condition likely. Mughal records additionally demonstrate that such a significant position was not given to any Hindu in the rule of Bahadur Shah Zafar. After enough examination, it was discovered that two Nayab(deputy) Kotwal were Hindu. Their names were Bhau Singh and Kashinath and they were posted in Lahore Gate, Delhi. In any case, no record of an individual named Gangadhar was found. The students of history have affirmed that Ghiyasuddin Ghazi was the name of city Kotwal in that time. 

In the rebellion, in view of the terrible massacre, numerous families alongside his family were totally demolished and every one of the reports and letters identified with his family were pulverized. Along these lines, in the wake of losing all that, they fled to Agra and they began another life there...