Below are some vital information and statistics from UN Water

biodiversity and  freshwater processOn average, high-income countries treat about 70% of the municipal and industrial wastewater they generate. That ratio drops to 38% in upper-middle-income countries and to 28% in lowermiddle-income countries. In low-income countries, only 8% undergoes treatment of any kind. These estimates support the often-cited approximation that, globally, over 80% of all wastewater is discharged without treatment.

SOURCE: WWAP (United Nations World Water Assessment Programme). 2017.
The United Nations World Water Development Report 2017.
Wastewater: The Untapped Resource. Paris, UNESCO. ISBN 978-92-3-100201-4

biodiversity and  freshwater processMany industries, some of them known to be heavily polluting (such as leather and chemicals) — are moving from high-income countries to emerging market economies. Despite improvements in some regions, water pollution is on the rise globally.

biodiversity and  freshwater processProjected increases in fertilizer use for food production and in wastewater effluents over the next three decades suggest there will be a 10-20 percent global increase in river nitrogen flows to coastal ecosystems.

biodiversity and  freshwater processOnly 1% of the earth's surface is covered with freshwaters but they are habitat for over 10% of all animals and over 35% of all vertebrate species. Freshwater animals are disappearing at a much faster rate than animals on land or at sea.

BioFresh. Biodiversity of Freshwater Ecosystems: Status, Trends, Pressures, and Conservation Priorities

Whiles there are many factors contributing to this, water pollution and contamination are key contributing factors.

Do you know about the Flint Michigan Water Contamination Crisis?
HERE is a serious example from Flint, Michigan in the USA.