Water supply system

A water supply system or 'water supply network' is an engineering system which provides a supply of water. 
A water supply system typically includes: 
The second part of the system is dealing with the sewage and waste water which is eventually put back or comes back into the system. If this' waste water' is not purified, cholera and typhoid epidemics will occur, and still do occur, in cities where the water engineering has not kept pace with population increase. 
This type of system was a consequence of the work of John Snow on the mid-19th century cholera plagues in London. Despite all efforts, epidemics do still occur if there are leaks in the underground sewage system and leaks in the underground water pipes.