Common types of water pollution that we know may be from the city and factories. Such as throwing trash into the river, or production waste that are dumped into bodies of water. However, water pollution can also be sourced from farmlands. There are a lot of activities on a farm field, that includes planting crops and keeping the pests at bay. So there is bound to be the use of chemicals in order to increase crops production.

Fertilizers are known to help crops increase production by supplying the plant with its needed nutrition. Meanwhile, insecticides or pesticides may be used by farmers to combat pests. However, with the use of these chemicals, they become even more dangerous once rain starts to fall down. Water that fall on the crops and land would wash off the chemicals. Then these water that contains chemical would flow to the nearest body of water and thus pollute them.

The bodies of water that contains runoff chemicals from farmland would be rich in certain nutrition, where this can cause further pollution as the added nutrition would be consumed by other organism causing them to increase in population. This is also known as eutrophication. An example would be an algae bloom, where a body of water would be covered extensively by them and then cause a lack of oxygen within the water that other organism such as fish needs to survive on. This lack of oxygen is because the algae would use them in their growth, where they are able to grow due to the availability of nutrition from the runoff chemicals that were not there before.