Over 70,000 different water contaminants have been identified. There are 12,000 different toxic chemicals used in industry, and more than 500 new chemicals made ​​each year.
About 450 cubic kilometers of wastewater are transported annually by rivers and streams to the coasts.

watervervuilingafgevoerdIn 1988, the creation of a plastic ocean or plastic soup was predicted: plastic garbage that would flush together by ocean currents. Charles Moore discovered the waste archipelago and studied it since 2000. Plastic fractions pass through fish and birds in the food chain where they occupy as estrogen a position as a female hormone. The waste soup measures 1 to 15 million km², or 100 million tonnes.

Why do animals not become sick after drinking ditch water, and we do?
Animals, because they live outside and drink constantly rain and surface water, have grown a progressive resistance. (Botulism and blue algae of course remain dangerous, even deadly).
We are, since it flows from the tap – common with good water even to wash us, to do the laundry, to brush teeth, to clean, to wash clothes. In other countries it is different. That’s why we are sometimes sick when we brush our teeth with local tap water, or eat food which is rinsed with tap water, while the locals are obviously not affected by it.
We no longer play in streams and ponds (which were previously less contaminated), only in pools. So we have no (more) this resistance. (See also hygiene hypothesis.)

Is surface water drinkable?
Besides bacteriological pollution there now is also the chemical pollution from agriculture and industry.
Probably drinking ditch water will not increase longevity (including for animals). Against bacteria we still can built up resistance, but some chemical substances accumulate in the body.
The concentration is crucial. PCBs and dioxins are toxic, persistent and cancer causative. And often difficult to remove from the water. Heavy metals also are dangerous.

Ocean : international trash. (E. Constant Sr.)

“Filthy water cannot be washed”. (West African Proverb)