Officials said the discharged water would not pose a significant threat to human health, but local fishermen have reacted angrily.

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This wastewater is either discharged directly into open water bodies or leaches into the subsoil.

UNESCO: Water resources in the Asia-Pacific region are increasingly threatened by pollution and vulnerable to natural disasters. | United Nations Educational, Scientific and Cultural Organization

It said clear, sterile water would be discharged and there would be a back-up system in case of error.

BBC: Aerial view of Treyarnon Bay

It also found no threat from the warmer water that is discharged back into the river or from any radioactive elements escaping from the plants into the Hudson.

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But the other 45% of recycled waste water was simply discharged at sea or released on to the land, where it had been pushing up groundwater levels, and eventually resulted in the creation of Lake Zakher.

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He said that "means worrying about the way in which the drilling takes places, it means worrying about making sure the methane is captured rather than discharged to the air and it means making sure that none of the contaminated water gets into the ground water that sometimes can fill our water supplies".

BBC: UK

Thames Water said the new tunnel is needed to stop increasing amounts of sewage being discharged into the Thames from the Victorian sewers.

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But a perennial challenge has been in getting the water clean enough that it can be reused in the next frack job or simply discharged down a river or stream.

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When discharged into waterways, they cause excessive growth of algae, which can smell bad and which robs the water of oxygen that fish need to survive.

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