Why does every major city get flooded in very mild rainfall?

What steps should the government take to improve it?

Our expectations from the drainage system are similar to expectations from our political class.

We expect both to function 100% efficiently, and then we dump everything that we don’t want to handle.

In case of drainage these unwanted things maybe :

1. Sanitary Pads
2. Diapers
3. Food leftover, sometimes bones of the slaughtered animals.
4. Construction waste.
5. Domestic and industrial waste.

Now depending on the region, average rainfall ranges between 10 days to 60 days throughout the year.

The issue gets even more complicated when the entire town planning approach is based on more than century old European urban design philosophies, which were evolved for European conditions of centralisation of everything, quite different to decentralised culture like ours where every 200 KM the dialect changes, so do cultural habits, including water.

Due to this single one thumb rule for all approaches we just build bigger and bigger and bigger drains to take the rains of a particular block or Colony to some kilometres away either to a river or somewhere outside the city.

On the day it rains, the drain channels are simply blocked. The rain (water) follows a path of least resistance and starts flowing in the low-lying areas in the vicinity.

The soil of this low lying area has got a certain holding / absorption capacity and till that time it doesn’t create a nuisance. The moment it gets beyond saturation level the area starts to get flooded.