The most ancient system yet discovered
i. Mackay has described it as complete ancient because of well planned, systematic and unique like its contemporary civilization particularly drainage system. Cleanliness part was also considered.
ii. Yes , in large cities like Mohenjo-Daro and small settlement like Lethal drainage was unique.
iii. Features of domestic drainage system
a. Every house was connected with the street drain
b. The main channel were made of brick set in mortar and were covered with loose bricks that could be removed for cleaning
c. In some cases, limestone was used for the covers.
d. House drains first emptied into a sump or cesspit into which solid matter settled while wastewater flowed out into the street drains.
e. Very long drainage channels were provided at intervals with sumps for Cleaning.