Population density is the amount of people per square kilometre. Areas may have high population density or low population density. Both circumstances can bring their own problems.
Problems associated with areas of very high population density.
Case study: Kolkata in the Sub-Continent of India
Lack of open space-
This is when there is no room left to build on and people are crammed very tight together. This is more common in very poor parts of the city.
Shortage of clean water-
People in Kolkata have to share water with millions of others. Many do not have access to clean water at all. They may have to drink dirty water, which often leads to sickness.
Sewage runs through the streets in open drains. Rubbish piles up. Air pollution is very bad.