Top 5 Ways Water Gets Polluted

Empty beach chairs rest in the sand as oil washes ashore

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If you thought to throw your sandwich wrapper in a stream while camping was the most common form of water pollution, think again: from agricultural runoff to waste treatment, pollution affects more and more of the Earth's water supply every minute. Check out five of the most invasive and damaging types of water pollution (but please: still throw that sandwich wrapper in the trashcan).

Sewage and Fertilizer

Sewage doesn't present as big of a problem as some other pollutants, but it does have its dangers: in small quantities, it breaks down naturally and doesn't harm water at all, but in large quantities, it depletes the amount of oxygen in the water. When too much oxygen is erased, the polluted area can't support sea life. These areas are known as "dead zones," and there are more than 400 of them around the world, causing major damage to the health of the oceans.

Acid Rain

Though the acid rain-awareness campaign has made this less of an issue than it was in the past, it's still a major pollution problem. A quick refresher on the how: the burning of fossil fuels releases compounds that interact with the H20 in the air, creating a modified version of the raindrop— one that includes nitric and sulfuric acid, which pollutes the water and ground that's affected by the rain. Too much of those acids inhibit plant growth, and soil damage on a major scale would take eons to repair— which makes the soil a "non-renewable resource," according to the U.S. Geological Survey.

Non-point Sources

All water pollution happens in one of two ways: via non-point or point systems. Non-point pollution comes from indirect sources, like agricultural runoff, mining waste, paved roads, and industrial activity. It's impossible to trace the original polluter in these cases, but toxic chemicals and compounds make their way into the water system just the same— through rainwater drainage, melting snow, and running rivers.

The Oil Industry

Everything about the oil industry— drilling, moving, laying pipeline, shipping— opens up the possibility for water pollution. From rigs that are compromised by foul weather (like those on the Gulf Coast) to barges that have accidental spills, the damage is never intentional, but it's still one of the major dangers facing clean water and marine life.


This may not seem like such a bad thing— after all, hot water and cold water even out eventually, right? Right— but until then, discharging hot water while cooling power plants means changing the temperature of the water source, which can encourage the species density to change and alter the biology of the water. Thermal pollution, then, can be just as damaging as bacterial or sediment pollution.