Design period of main sewers is taken as:

Detailed Solution:

Design period is defined as the time period for which the component remains functional
examples;- design period of some components
land acquisition less than or equal to 30years
Main sewer 30 years
Non conventional sewers 15 years
pumping mains 30 years
 pumping station 30 years
pumping machinery 15 years
sewage treatment plant 15 years
 effluent disposal 30 years
effluent utilisation 15 years