Question

why is stagnant water harmful?

Answer 1

Malaria and dengue are among the maindangers of stagnant water, which can become a breeding ground for the mosquitoes that transmit these diseases.Stagnant water can be dangerous for drinking because it provides a better incubator than running water for many kinds of bacteria and parasites

Answer 2

Stagnant water is harmful since it contains a number of harmful bacteria and micro-organisms which can even kill us by spreading diseases.
Like cholera, dysentery, loose motions, etc. Many insects such as mosquitoes and house flies make it as there breeding place. They can spread malaria, philaria, dengue, chikungunya.