Question

Plastic bags block drains and gutters and
stop the flow of rain water. It causes an
overflow of water that becomes a
ground for mosquitoes.
This can cause various kinds of diseases.​

Answer 1

Plastic grocery bags are lighter (less dense) than water; hence, they float over water. This is why they accumulate on the beaches when disposed of indiscriminately. In the case of a vertical grill in the drainage system, the water will flow through the grill with the plastic bags floating on the surface.

In the case of a horizontal grill such as the one found on the roadside, the bags will be displaced by flowing water. By applying this logic, it is difficult to understand the reason for plastic grocery bags is responsible for blocking drains. But if they are in excess with other solid waste in drains they can block the drain as they are impermeable for water.