Expense of building and maintenance
Buying and installing good drainage systems would be a costly endeavour as these are not simple tasks and would require people with expertise which would make their hiring costs more costly. Maintaining the drainage system is a must, as a not well maintained drainage system would cause more problems than solve them, clogged pipes would lead to overflow of the toxic substances that are disposed in it. Teams will have to be made with the goal of unclogging and cleaning these pipes which would also be a costly endeavour.
Contamination in bodies of water
Most waste from drainage systems are disposed of in natural bodies of water. Subsurface pipes have the chance of carrying nitrates to these bodies of water which would contaminate the water. These reasons of course could lead to these bodies of water getting contaminated which would make these bodies of water deadly. This problem can easily be solved by incineration plants and such but this isn't feasible in the current state of our country. This would need it to be even more closely maintained as contaminated water could lead to national catastrophes which would be deadly to the population.
